0001213900-20-036777 | S-1/A | XBRL Viewer | B Riley Principal Merger Corp II

Note payable - related party

177,329,013

50,001

Current liabilities:

Accounts payable

21,912

325

278

Accrued expenses

1,786,970

44,194

50,000

Total current liabilities

1,853,076

50,325

278

Long term liabilities

Class A Common stock subject to possible redemption; 17,074,119 (at redemption value of approximately $10.10 per share at June 30, 2020)

1,853,076

50,325

278

Commitments

170,475,931

Stockholders' equity (deficit):

Preferred stock, $0.0001 par value; 1,000,000 shares authorized; none issued and outstanding

Class A Common stock, $0.0001 par value; 100,000,000 shares authorized; 1,075,881 issued and outstanding as of June 30, 2020 and none issued and outstanding as of December 31, 2019 (excluding 17,074,119 subject to possible redemption)

127

Class B Common stock, $0.0001 par value; 25,000,000 shares authorized; 4,375,000 issued and outstanding as of September 30, 2020 and 5,750,000(1) outstanding as of December 31, 2019, see Equity Statement

437

575

Additional paid-in capital

7,047,891

Accumulated deficit

(2,048,449)

(899)

(852)

Total stockholders' equity (deficit)

5,000,006

(324)

(277)

^[1]

Total liabilities and stockholders' equity (deficit)

177,329,013

$ 50,001

EOS ENERGY STORAGE, LLC

Current assets:

Cash

6,534,000

862,000

$ 5,498,000

Grants receivable

286,000

326,000

678,000

Inventory

78,000

801,000

Accounts receivable

35,000

Receivable on sale of state tax attributes

4,060,000

Vendor deposits

646,000

252,000

Vendor deposits - related party

3,143,000

Deferred transaction costs

2,386,000

Prepaid and other current assets

211,000

484,000

383,000

Total current assets

13,319,000

5,984,000

7,360,000

Property and equipment, net

5,817,000

5,316,000

6,542,000

Intangible assets, net

330,000

360,000

400,000

Investment in joint venture

2,017,000

589,000

Security deposit

810,000

808,000

744,000

Accounts payable and accrued expenses

22,293,000

13,057,000

15,046,000

Current liabilities:

15,453,000

8,181,000

9,208,000

Provision for firm purchase commitments

5,807,000

Convertible notes payable - related party

108,353,000

76,559,000

2,350,000

Notes payable

1,000,000

Capital lease, current portion

11,000

13,000

56,000

Embedded derivative liability

371,000

1,681,000

Long-term debt, current portion

912,000

Contract liabilities, current portion

310,000

300,000

58,000

Total current liabilities

131,217,000

86,734,000

12,672,000

Long term liabilities

Deferred rent

750,000

663,000

494,000

Long-term debt

491,000

Capital lease

11,000

17,000

46,000

Contract liabilities

660,000

Total long term liabilities

1,252,000

680,000

1,200,000

CONTINGENTLY REDEEMABLE PREFERRED UNITS (NOTE 13)

132,469,000

87,414,000

13,872,000

Commitments

118,624,000

109,365,000

105,548,000

Stockholders' equity (deficit):

Members' capital

20,616,000

20,346,000

20,211,000

Accumulated deficit

(249,416,000)

(204,068,000)

(124,585,000)

Total stockholders' equity (deficit)

(228,800,000)

(183,722,000)

(104,374,000)

Total liabilities and stockholders' equity (deficit)

$ 22,293,000

$ 13,057,000

$ 15,046,000

[1]	Includes an aggregate of 750,000 shares that are subject to forfeiture to the extent that the underwriter's over-allotment is not exercised in full (Note 4). On February 3, 2020, the Company conducted a 1:575 stock split and reclassification for each share outstanding (Note 4).

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($)

Sep. 30, 2020

Feb. 14, 2020

Dec. 31, 2019

Preferred stock par value

$ 0.0001

Preferred stock, shares authorized

1,000,000

Preferred Stock, Shares Issued

Preferred Stock, Shares Outstanding

EOS ENERGY STORAGE, LLC

Preferred stock liquidation preference

$ 156,936,000

$ 136,816,000

Class A Common Stock

Commonn stock par value

$ 0.0001

Common stock, shares authorized

100,000,000

1,000,000

1,271,195

Common stock, shares authorized

1,271,195

Redemption, par value

Redemption, shares

16,878,905

Redemption, per share

$ 10.10

Class B Common Stock

Commonn stock par value

$ 0.0001

25,000,000

4,375,000

5,750,000

4,375,000

Selling, general and administrative expenses

4,375,000

5,750,000

^[1]

[1]	Includes an aggregate of 750,000 shares that are subject to forfeiture to the extent the underwriter’s overallotment is not exercised in full (Note 4).

Condensed Consolidated Statements of Operations (Unaudited) - USD ($)

2 Months Ended

3 Months Ended

7 Months Ended

9 Months Ended

12 Months Ended

Feb. 14, 2020

Sep. 30, 2020

Sep. 30, 2019

Dec. 31, 2019

Sep. 30, 2020

Sep. 30, 2019

Dec. 31, 2019

Dec. 31, 2018

Costs and expenses

Total costs and expenses

$ 1,978,148

$ 2,075,279

Operating loss

(1,978,148)

(2,075,279)

$ 47

$ 278

Loss before income taxes

(47)

(278)

Provision for income taxes

Other income (expense)

Interest income

16,294

27,682

Weighted average shares outstanding, basic and diluted

$ (47)

$ (1,961,854)

$ (278)

$ (2,047,597)

^[1],[2]

5,450,881

5,000,000

7,654,134

Weighted average basic shares outstanding

^[3]

5,000,000

Weighted average diluted shares outstanding

^[3]

5,000,000

Basic and diluted loss per common share

$ (0.37)

$ 0.00

$ (0.27)

Basic loss per share

$ 0.00

Diluted loss per share

$ 0.00

EOS ENERGY STORAGE, LLC

Revenue

Total revenue

$ 35,000

$ 211,000

$ 496,000

Costs and expenses

Cost of goods sold

6,161,000

7,565,000

8,332,000

9,708,000

Research and development expenses

8,360,000

10,105,000

11,755,000

14,574,000

General and administrative expenses

8,241,000

5,228,000

7,710,000

7,158,000

Grant (income) expense, net

728,000

(526,000)

(469,000)

1,418,000

Total costs and expenses

23,490,000

22,372,000

27,328,000

32,858,000

Operating loss

(23,455,000)

(22,161,000)

(26,832,000)

(32,858,000)

Provision for income taxes

Other income (expense)

Sale of state tax attributes

4,060,000

4,476,000

Loss from equity in unconsolidated joint venture

(133,000)

(178,000)

Interest income

2,000

28,000

Interest expense

(115,000)

(6,000)

Interest expense - related party

(23,366,000)

(30,851,000)

(49,708,000)

(144,000)

Loss on extinguishment of convertible notes

(6,111,000)

Change in fair value, embedded derivative

1,721,000

(1,528,000)

(716,000)

Total other income (expense)

(21,893,000)

(38,494,000)

(52,651,000)

4,360,000

Balance, shares at Dec. 31, 2017

$ (45,348,000)

$ (60,655,000)

$ (79,483,000)

$ (28,498,000)

[1]	Excludes an aggregate of up to 16,878,805 shares subject to possible redemption.
[2]	Net loss per common share - basic and diluted excludes income attributable to common stock subject to possible redemption of $31,646 and $41,955 for the three and nine months ended September 30, 2020, respectively (see Note 2).
[3]	Excludes an aggregate of 656,250 shares that are subject to forfeiture to the extent that the underwriters over-allotment is not exercised in full (Note 4). On February 3, 2020, the Company conducted a 1:575 shares for each share outstanding (Note 4).

Condensed Consolidated Statements of Operations (Unaudited) (Parenthetical) - USD ($)	2 Months Ended	3 Months Ended	9 Months Ended
	Feb. 14, 2020	Sep. 30, 2020	Sep. 30, 2020
Income Statement [Abstract]
Shares are subject to possible redemption			16,878,805
Net loss per common share - basic and diluted excludes income attributable to common stock subject to possible redemption		$ 31,646	$ 41,955
Shares are subject to forfeiture	656,250

Condensed Consolidated Statements of Changes in Stockholders' Equity (Deficit) (Unaudited) - USD ($)

Class A Common Stock

Class B Common Stock

Common Equity

EOS ENERGY STORAGE, LLC

Additional Paid in Capital

Accumulated Deficit

EOS ENERGY STORAGE, LLC

Accumulated Deficit

EOS ENERGY STORAGE, LLC

Total

EOS ENERGY STORAGE, LLC

Balance at Dec. 31, 2017

$ 20,074,000

$ (96,087,000)

$ (76,013,000)

68,190,000

$ 137,000

137,000

Balance, shares at Dec. 31, 2018

(28,498,000)

$ (28,498,000)

(28,498,000)

Balance at Dec. 31, 2018

$ 20,211,000

(124,585,000)

(104,374,000)

68,190,000

$ 105,000

105,000

Balance, shares at Sep. 30, 2019

(60,655,000)

Balance at Sep. 30, 2019

$ 20,316,000

(185,240,000)

$ 1

164,924,000

68,190,000

Balance at Dec. 31, 2018

$ 20,211,000

(124,585,000)

(104,374,000)

Balance, shares at Dec. 31, 2018

68,190,000

$ 135,000

135,000

Balance, shares at Dec. 31, 2019

(79,483,000)

Balance at Dec. 31, 2019

^[1]

$ 575

^[1]

$ 20,346,000

^[1]

(204,068,000)

(852)

^[1]

(183,722,000)

(277)

^[1]

(183,722,000)

^[1]

5,750,000

^[1]

68,190,000

Balance at Jun. 02, 2019

^[2]

$ 575

(574)

Balance, shares at Jun. 02, 2019

^[2]

5,750,000

Balance, shares at Sep. 30, 2019

Balance at Sep. 30, 2019

$ 20,316,000

(185,240,000)

164,924,000

68,190,000

Balance at Jun. 02, 2019

^[2]

$ 575

(574)

Balance, shares at Jun. 02, 2019

^[2]

5,750,000

Balance, shares at Dec. 31, 2019

(278)

Balance at Dec. 31, 2019

^[1]

$ 575

^[1]

$ 20,346,000

^[1]

(204,068,000)

(852)

^[1]

(183,722,000)

(277)

^[1]

(183,722,000)

^[1]

5,750,000

^[1]

68,190,000

Balance, shares at Feb. 14, 2020

(47)

Balance at Feb. 14, 2020

$ 575

(899)

(324)

5,750,000

Balance at Dec. 31, 2019

^[1]

$ 575

^[1]

$ 20,346,000

^[1]

(204,068,000)

(852)

^[1]

(183,722,000)

(277)

^[1]

(183,722,000)

Balance, shares at Dec. 31, 2019

^[1]

5,750,000

^[1]

68,190,000

Cancellation of Founder Shares

^[1]

$ (72)

Cancellation of Founder Shares, shares

^[1]

(718,750)

Forfeiture of Class B common stock by Sponsor

$ (66)

Forfeiture of Class B common stock by Sponsor, shares

(656,250)

Class A common stock issued net of offering costs of $3,976,189

$ 1,750

^[1]

171,022,061

171,023,811

Class A common stock issued net of offering costs of $3,976,189, shares

17,500,000

^[1]

Private Placement of Class A common stock issued

$ 65

^[1]

6,499,935

6,500,000

Private Placement of Class A common stock issued, shares

650,000

^[1]

Common stock subject to possible redemption

$ 1,688

^[1]

170,474,243

Common stock subject to possible redemption, shares

(16,878,805)

^[1]

$ 270,000

270,000

Balance, shares at Sep. 30, 2020

^[1]

(45,348,000)

(85,743)

(45,348,000)

(2,047,597)

(45,348,000)

Balance at Sep. 30, 2020

$ 437

$ 20,616,000

7,047,891

(249,416,000)

(228,800,000)

5,000,006

(228,800,000)

4,375,000

68,190,000

Balance at Jun. 30, 2020

^[1]

$ 108

$ 437

5,086,056

(86,595)

5,000,006

Balance, shares at Jun. 30, 2020

^[1]

1,075,881

4,375,000

Cancellation of Founder Shares

Forfeiture of Class B common stock by Sponsor

Common stock subject to possible redemption

$ 19

1,961,835

1,961,854

Common stock subject to possible redemption, shares

195,314

Balance, shares at Sep. 30, 2020

$ (1,961,854)

(1,961,854)

Balance at Sep. 30, 2020

$ 437

$ 20,616,000

$ 7,047,891

$ (249,416,000)

$ (228,800,000)

$ 5,000,006

$ (228,800,000)

4,375,000

68,190,000

[1]	Includes an aggregate of 750,000 shares that are subject to forfeiture to the extent that the underwriter's over-allotment is not exercised in full (Note 4). On February 3, 2020, the Company conducted a 1:575 stock split and reclassification for each share outstanding (Note 4).
[2]	Includes an aggregate of 656,250 shares that are subject to forfeiture to the extent that the underwriters over-allotment is not exercised in full (Note 4). On February 3, 2020, the Company conducted a 1:575 shares for each share outstanding (Note 4).

Condensed Consolidated Statements of Changes in Stockholders' Equity (Deficit) (Parenthetical) - USD ($)	Feb. 14, 2020	Feb. 03, 2020
Statement of Stockholders' Equity [Abstract]
Shares are subject to forfeiture	656,250
Stock split		The Company conducted a 1:575 stock split and reclassification for each share outstanding
Share outstanding, description		The Company conducted a 1:575 shares for each share outstanding (Note 4).
Stock issued net of offering costs

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	2 Months Ended	4 Months Ended	7 Months Ended	9 Months Ended		12 Months Ended
	Feb. 14, 2020	Sep. 30, 2019	Dec. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Net loss	$ (47)		$ (278)	$ (2,047,597)
Adjustment to reconcile net loss to net cash used in operating activities
Interest earned on investments held in Trust Account				(27,682)
Changes in operating assets and liabilities:
Prepaid expenses				(236,226)
Increase in accounts payable and accrued expenses				1,808,604
Increase in payable to related party			(1)	44,195
Increase in accounts payable	47		278
Net cash used in operating activities			(1)	(458,706)
Cash flows from investing activities:
Proceeds deposited in Trust Account				(176,750,000)
Net cash used in investing activities				(176,750,000)
Cash flows from financing activities:
Proceeds from sale of Class B common stock			1
Proceeds from note payable - related party	50,000			100,000
Repayment of note payable - related party				(100,000)
Proceeds from sale of Units in Public Offering				175,000,000
Proceeds from sale of Units in Private Placement				6,500,000
Payment of underwriting discounts				(3,500,000)
Payment of offering expenses				(476,189)
Net cash provided by financing activities	50,000		1	177,523,811
Net increase (decrease) in cash and cash equivalents	50,000			315,105
Cash, beginning of year
Cash, end of period	50,000			315,105
Non-cash investing and financing activities
Original value of Class A Common stock subject to possible redemption				172,437,623
Change in value of Class A Common stock subject to possible redemption				(1,961,692)
Supplemental disclosures:
Interest paid
Taxes paid
EOS ENERGY STORAGE, LLC
Net loss				(45,348,000)	$ (60,655,000)	(79,483,000)	$ (28,498,000)
Adjustment to reconcile net loss to net cash used in operating activities
Stock-based compensation				270,000	105,000	135,000	137,000
Depreciation and amortization				1,142,000	1,770,000	2,123,000	2,417,000
Impairment of property and equipment					1,590,000	1,590,000	1,441,000
Provision for firm purchase commitments				5,807,000
Loss from equity in unconsolidated joint venture				133,000		178,000
Accreted interest on convertible notes payable - related party				23,366,000	30,851,000	49,708,000
Loss on extinguishment of convertible notes – related party					6,111,000	6,111,000
Change in fair value, embedded derivative				(1,721,000)	1,528,000	716,000
Other				6,000	(64,000)	(52,000)
Changes in operating assets and liabilities:
Receivable on sale of state tax attributes				4,060,000		(4,060,000)
Prepaid expenses				273,000	(579,000)	(353,000)	415,000
Inventory				(78,000)	277,000	634,000	(489,000)
Grants receivable				40,000	352,000	352,000	(91,000)
Vendor deposits – related party				(3,143,000)
Vendor deposits				(394,000)	316,000
Security deposits				(2,000)	(45,000)	(64,000)
Accounts receivable				(35,000)
Increase in accounts payable and accrued expenses				5,106,000	(2,546,000)	(1,070,000)	(521,000)
Contract liabilities				10,000	99,000	(468,000)	58,000
Deferred rent				87,000	127,000	169,000	213,000
Net cash used in operating activities				(10,595,000)	(20,763,000)	(23,834,000)	(24,918,000)
Cash flows from investing activities:
Investment in joint venture				(1,561,000)		(601,000)
Purchases of property and equipment				(1,839,000)	(1,858,000)	(2,299,000)	(1,697,000)
Net cash used in investing activities				(3,400,000)	(1,858,000)	(2,900,000)	(1,697,000)
Cash flows from financing activities:
Capital lease payments				(8,000)	(42,000)	(72,000)	(47,000)
Proceeds from issuance of convertible notes payable - related party				8,839,000	17,390,000	19,346,000	4,268,000
Proceeds from Paycheck Protection Program loan				1,257,000
Proceeds from other financing				195,000
Repayment of other financing				(49,000)
Proceeds / (repayment) of short term notes payable					(1,000,000)	(1,000,000)	1,000,000
Proceeds attributable to beneficial conversion features of convertible notes payable - related party						1,793,000
Issuance of contingently redeemable preferred stock				9,259,000	1,289,000	2,031,000	24,854,000
Net cash provided by financing activities				19,666,000	17,637,000	22,098,000	30,075,000
Net increase (decrease) in cash and cash equivalents				5,672,000	(4,984,000)	(4,636,000)	3,460,000
Cash, beginning of year	$ 862,000			862,000	5,498,000	5,498,000	2,038,000
Cash, end of period		$ 514,000	$ 862,000	6,534,000	514,000	862,000	5,498,000
Non-cash investing and financing activities
Contribution of inventory to joint venture						167,000
Conversion of notes payable to members' capital							5,918,000
Accrued and unpaid capital expenditures				329,000	146,000	93,000	444,000
Accrued and unpaid deferred transaction costs				2,386,000
Supplemental disclosures:
Interest paid				$ 115,000	$ 6,000	$ 6,000	$ 3,000

Organization, Nature of Business Operations and Going Concern	2 Months Ended	9 Months Ended
	Feb. 14, 2020	Sep. 30, 2020
Organization and Nature of Business Operations [Abstract]
ORGANIZATION, NATURE OF BUSINESS OPERATIONS AND GOING CONCERN	NOTE 1 — DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS Organization and General B. Riley Principal Merger Corp. II (the “Company”), a blank check corporation, was incorporated as a Delaware corporation on June 3, 2019. The Company is an emerging growth company, as defined in Section 2(a) of the Securities Act of 1933, as amended, (the “Securities Act”), as modified by the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). The Company was formed for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (a “Initial Business Combination”). At February 14, 2020, the Company had not commenced any operations. All activity of the Company includes the activity of the Company from inception and activity related to the proposed initial public offering (the “Proposed Offering”) described below. The Company will not generate any operating revenues until after completion of its Initial Business Combination, at the earliest. The Company will generate non-operating income in the form of interest income on cash and cash equivalents from the proceeds derived from the Proposed Offering described below. The Company has selected December 31st as its fiscal year end. Sponsor and Proposed Financing The Company’s sponsor is B. Riley Principal Sponsor Co. II, LLC (the “Sponsor”), a Delaware limited liability company and a wholly owned indirect subsidiary of B. Riley Financial, Inc. (“B. Riley Financial”). On February 4, 2020, the Sponsor agreed to loan the Company up to $300,000 (see note 4) to support the Company’s initial formation and operations. The Company’s ability to commence meaningful operations and finance its Initial Business Combination is contingent upon obtaining adequate financial resources through the proposed $175,000,000 ($201,250,000 if the underwriters’ over-allotment is exercised in full) initial public offering of Units (as defined below) (Note 3). Upon the closing of the Proposed Offering and the Private Placement, $176,750,000 (or $203,262,500 if the underwriters’ over-allotment option is exercised in full — Note 3) will be held in a trust account (the “Trust Account”) (discussed below). The Trust Account The proceeds to be held in the Trust Account will be invested only in U.S. government treasury bills with a maturity of 185 days or less or in money market funds registered under the Investment Company Act and compliant with Rule 2a-7 thereof that maintain a stable net asset value of $1.00. Unless and until the Company completes the Initial Business Combination, it may pay its expenses only from the net proceeds of the Proposed Offering held outside the Trust Account, which will be approximately $500,000 in working capital after the payment of approximately $750,000 in expenses relating to the proposed Offering, and any loans or additional investments from the Sponsor, members of the Company’s management team or any of their respective affiliates or other third parties. Except with respect to interest earned on the funds held in the Trust Account that may be released to the Company to pay its taxes, the proceeds from the Proposed Offering may not be released from the Trust Account until the earliest of: (i) the completion of the Initial Business Combination; (ii) the redemption of any public shares properly tendered in connection with a stockholder vote to amend the Company’s amended and restated certificate of incorporation to modify the substance or timing of the Company’s obligation to redeem 100% of its public shares if it does not complete the Initial Business Combination within 18 months from the closing of the Proposed Offering; or (iii) the redemption of all of the Company’s public shares if the Company is unable to complete the Initial Business Combination within 18 months from the closing of the Proposed Offering (at which such time up to $100,000 of interest shall be available to the Company to pay dissolution expenses), subject to applicable law. The proceeds deposited in the Trust Account could become subject to the claims of the Company’s creditors, if any, which could have priority over the claims of the Company’s public stockholders. Initial Business Combination The Company’s management has broad discretion with respect to the specific application of the net proceeds of the Proposed Offering, although substantially all of the net proceeds of the Proposed Offering and the Private Placement are intended to be generally applied toward consummating an Initial Business Combination. The Initial Business Combination must occur with one or more businesses or assets with a fair market value equal to at least 80% of the net assets held in the Trust Account (excluding the amount of any deferred underwriting discount). There is no assurance that the Company will be able to successfully effect an Initial Business Combination. The Company, after signing a definitive agreement for an Initial Business Combination, will provide its public stockholders’ with the opportunity to redeem all or a portion of their shares upon the completion of the Initial Business Combination, either (i) in connection with a stockholder meeting called to approve the business combination or (ii) by means of a tender offer. However, in no event will the Company redeem its public shares in an amount that would cause its net tangible assets to be less than $5,000,001. In such case, the Company would not proceed with the redemption of its public shares and the related Initial Business Combination, and instead may search for an alternate Initial Business Combination. If the Company holds a stockholder vote or there is a tender offer for shares in connection with an Initial Business Combination, a public stockholder will have the right to redeem its shares for an amount in cash equal to its pro rata share of the aggregate amount then on deposit in the Trust Account as of two business days prior to the consummation of the Initial Business Combination, including interest but less taxes payable. As a result, such shares of Class A common stock will be recorded at redemption amount and classified as temporary equity upon the completion of the Proposed Offering, in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 480, “Distinguishing Liabilities from Equity.” Pursuant to the Company’s amended and restated certificate of incorporation, if the Company is unable to complete the Initial Business Combination within 18 months from the closing of the Proposed Offering, the Company will (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but no more than ten business days thereafter redeem the public shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account including interest but less taxes payable (less up to $100,000 of interest to pay dissolution expenses), divided by the number of then outstanding public shares, which redemption will completely extinguish public stockholders’ rights as stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject in each case to the Company’s obligations under Delaware law to provide for claims of creditors and the requirements of other applicable law. The Sponsor and the Company’s officers and directors will enter into a letter agreement with the Company, pursuant to which they will agree to waive their rights to liquidating distributions from the Trust Account with respect to any Founder Shares and Private Placement Shares (as defined below) held by them if the Company fails to complete the Initial Business Combination within 18 months of the closing of the Proposed Offering. However, if the Sponsor or any of the Company’s directors or officers acquires shares of Class A common stock in or after the Proposed Offering, they will be entitled to liquidating distributions from the Trust Account with respect to such shares if the Company fails to complete the Initial Business Combination within the prescribed time period. In the event of a liquidation, dissolution or winding up of the Company after an Initial Business Combination, the Company’s remaining stockholders are entitled to share ratably in all assets remaining available for distribution to them after payment of liabilities and after provision is made for each class of stock, if any, having preference over the common stock. The Company’s stockholders have no preemptive or other subscription rights. There are no sinking fund provisions applicable to the common stock, except that the Company will provide its stockholders with the opportunity to redeem their public shares for cash equal to their pro rata share of the aggregate amount then on deposit in the Trust Account, under the circumstances, and, subject to the limitations, described herein. Going Concern Considerations At February 14, 2020, the Company had cash and cash equivalents of $50,000 and a note payable to the Sponsor in the amount of $50,000. Further, the Company expects to continue to incur significant costs in pursuit of its financing and acquisition plans. This condition raises substantial doubt about the Company’s ability to continue as a going concern. Management plans to address this uncertainty through the Proposed Offering as discussed in Note 3. There is no assurance that the Company’s plans to raise capital or to consummate an Initial Business Combination will be successful or successful within the required time period. The financial statements do not include any adjustments that might result from the outcome of this uncertainty.	NOTE 1 — ORGANIZATION, NATURE OF BUSINESS OPERATIONS AND GOING CONCERN Organization and General B. Riley Principal Merger Corp. II (the “Company”), a blank check company, was incorporated as a Delaware corporation on June 3, 2019. The Company is an emerging growth company, as defined in Section 2(a) of the Securities Act of 1933, as amended, (the “Securities Act”), as modified by the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). The Company was formed for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (a “Business Combination”). All activity of the Company from June 3, 2019 (inception) through September 30, 2020 relates to the Company’s formation, initial public offering (the “Public Offering”) described below and evaluating prospective acquisition targets for a potential Business Combination. The Company will not generate any operating revenues until after completion of its Business Combination, at the earliest. The Company will generate non-operating income in the form of interest income on cash and cash equivalents from the proceeds derived from the Public Offering described below. The Company has selected December 31st as its fiscal year end. On June 3, 2019, 10,000 shares of the Company’s common stock were issued to B. Riley Principal Investments, LLC. On February 3, 2020, the Company conducted a 1:575 stock split and reclassification, resulting in B. Riley Principal Investments, LLC holding 5,750,000 shares of Class B common stock (the “Founder Shares”). All of the Founder Shares were contributed to B. Riley Principal Sponsor Co. II, LLC (the “Sponsor”), a Delaware limited liability company and a wholly-owned indirect subsidiary of B. Riley Financial, Inc. (“B. Riley Financial”), in January 2020. Public Offering The Company completed the sale of 17,500,000 units (the “Units”) at an offering price of $10.00 per Unit in the Public Offering on May 22, 2020. The Sponsor purchased an aggregate of 650,000 Units at a price of $10.00 per Unit (the “Private Placement Units”) in a private placement that closed on May 22, 2020 simultaneously with the Public Offering (the “Private Placement”). The sale of the 17,500,000 Units in the Public Offering (the “Public Units”) generated gross proceeds of $175,000,000, less underwriting commissions of $3,500,000 (2% of the gross proceeds of the Public Offering) and other offering costs of $476,189. The Private Placement Units generated $6,500,000 of gross proceeds. Each Unit consists of one share of the Company’s Class A common stock, $0.0001 par value (each a “public share”), and one-half of one redeemable warrant, with each whole warrant exercisable for one share of Class A common stock (each, a “Warrant” and, with respect to the warrants underlying the Private Placement Units, the “Private Placement Warrants” and, collectively, the “Warrants”). One Warrant entitles the holder thereof to purchase one whole share of Class A common stock at a price of $11.50 per share. Sponsor and Note Payable — Related Party On February 4, 2020, the Sponsor agreed to loan the Company up to $300,000 (see Note 3) to support the Company’s initial formation and operations. In February 2020, the Company borrowed $50,000 and in April 2020 the Company borrowed an additional $50,000 which increased the Note Payable balance to $100,000 which was repaid in full in connection with the closing of the Public Offering using the proceeds from the Public Offering and the Private Placement. At September 30, 2020, there were no amounts outstanding on the Note Payable. The Trust Account Upon completion of the Public Offering, $176,750,000 of proceeds were held in the Company’s trust account at J.P. Morgan Chase Bank, N.A., with Continental Stock Transfer & Trust Company acting as trustee (the “Trust Account”) and have been invested in permitted United States “government securities” within the meaning of Section 2(a)(16) of the Investment Company Act of 1940, as amended, which we refer to as the Investment Company Act, having a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 promulgated under the Investment Company Act that invest only in direct U.S. government treasury obligations. Unless and until the Company completes the Initial Business Combination, it may pay its expenses only from the net proceeds of the Public Offering and the Private Placement held outside the Trust Account, which was $1,284,805 on May 22, 2020, of which $100,000 was used to pay the Note Payable to Sponsor and $476,189 was used to pay the offering costs. The balance in the Trust Account at September 30, 2020 was $176,777,682. Except with respect to interest earned on the funds held in the Trust Account that may be released to the Company to pay its taxes, the proceeds from the Public Offering may not be released from the Trust Account until the earliest of: (i) the completion of the Business Combination; (ii) the redemption of any public shares properly submitted in connection with a stockholder vote to amend the Company’s amended and restated certificate of incorporation to modify the substance or timing of the Company’s obligation to redeem 100% of its public shares if it does not complete the Business Combination by November 22, 2021, 18 months from the closing of the Public Offering; or (iii) the redemption of all of the Company’s public shares if the Company is unable to complete the Business Combination by November 22, 2021, 18 months from the closing of the IPO (at which such time up to $100,000 of interest shall be available to the Company to pay dissolution expenses), subject to applicable law. The proceeds deposited in the Trust Account could become subject to the claims of the Company’s creditors, if any, which could have priority over the claims of the holders of the Company’s public shares (the “public stockholders”). Business Combination The Company’s management has broad discretion with respect to the specific application of the net proceeds of the Public Offering, although substantially all of the net proceeds of the Public Offering and the Private Placement are intended to be generally applied toward consummating a Business Combination. The Business Combination must occur with one or more businesses or assets with a fair market value equal to at least 80% of the assets held in the Trust Account. There is no assurance that the Company will be able to successfully effect a Business Combination. The Company will provide its public stockholders with the opportunity to redeem all or a portion of their shares upon the completion of the Business Combination, either (i) in connection with a stockholder meeting called to approve the Business Combination or (ii) by means of a tender offer. However, in no event will the Company redeem its public shares in an amount that would cause its net tangible assets to be less than $5,000,001. If the Company holds a stockholder meeting to approve the Business Combination, a public stockholder will have the right to redeem its public shares for an amount in cash equal to its pro rata share of the aggregate amount then on deposit in the Trust Account as of two business days prior to the consummation of the Business Combination, including interest but less taxes payable. As a result, such shares of Class A common stock have been recorded at redemption amount and classified as temporary equity upon the completion of the Public Offering, in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 480, “Distinguishing Liabilities from Equity.” Pursuant to the Company’s amended and restated certificate of incorporation, if the Company is unable to complete the Business Combination by November 22, 2021, 18 months from the closing of the Public Offering, the Company will (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but no more than ten business days thereafter redeem the public shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account including interest earned on the funds held in the Trust Account and not previously released to the Company to pay franchise and income taxes (less up to $100,000 of interest to pay dissolution expenses), divided by the number of then outstanding public shares, which redemption will completely extinguish public stockholders’ rights as stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject in each case to the Company’s obligations under Delaware law to provide for claims of creditors and the requirements of other applicable law. There will be no redemption rights or liquidating distributions with respect to the Company’s warrants, which will expire worthless if the Company fails to complete the Business Combination within 18 months of the closing of the Public Offering. The Sponsor and the Company’s officers and directors have entered into a letter agreement with the Company, pursuant to which they have agreed to waive their rights to liquidating distributions from the Trust Account with respect to any Founder Shares and Private Placement Shares (as defined below) held by them if the Company fails to complete the Business Combination within 18 months of the closing of the Public Offering. However, if the Sponsor or any of the Company’s directors or officers acquires shares of Class A common stock in or after the Public Offering, they will be entitled to liquidating distributions from the Trust Account with respect to such public shares if the Company fails to complete the Business Combination within the prescribed time period. In the event of a liquidation, dissolution or winding up of the Company after an Business Combination, the Company’s remaining stockholders are entitled to share ratably in all assets remaining available for distribution to them after payment of liabilities and after provision is made for each class of stock, if any, having preference over the common stock. The Company’s stockholders have no preemptive or other subscription rights. The Company will provide its stockholders with the opportunity to redeem their public shares for cash equal to their pro rata share of the aggregate amount then on deposit in the Trust Account, under the circumstances, and, subject to the limitations, described herein. Letter Agreement The Company’s Sponsor, officers and directors have entered into a letter agreement with the Company, pursuant to which they have agreed, among other things (a) to waive their redemption rights with respect to any Founder Shares, Private Placement Shares and any Public Shares held by them in connection with the completion of the Business Combination, (b) to waive their redemption rights with respect to their Founder Shares, Private Placement Shares and public shares in connection with a stockholder vote to approve an amendment to the Company’s amended and restated certificate of incorporation to modify the substance or timing of its obligation to redeem 100% of its public shares if it does not complete an Business Combination within 18 months from the closing of the Public Offering and (c) to vote their Founder Shares and any Public Shares purchased during or after the Public Offering (including in open market and privately negotiated transactions) in favor of the Initial Business Combination. Going Concern Consideration The Company has principally financed its operations from inception using proceeds from the promissory note from the Sponsor prior to the Public Offering and such amount of proceeds from the Public Offering and Private Placement that were placed in an account outside of the Trust Account (as defined below) for working capital purposes. In connection with the closing of the Public Offering and the Private Placement on May 22, 2020, an amount of $176,750,000 (or $10.10 per Class A common stock sold to the public in the Public Offering included in the Public Units) was placed in the Trust Account. As of September 30, 2020, the Company had $315,105 in its operating bank account, $176,777,682 in cash and cash equivalents held in the Trust Account to be used for a Business Combination or to repurchase or redeem its Class A Common Stock in connection therewith and a working capital deficit of $1,229,514, which includes Delaware franchise taxes payable of $72,231 (which is included in accrued expenses at September 30, 2020) as franchise taxes are paid from the Trust account from interest income earned. If our funds are insufficient to meet the expenditures required for operating our business through the consummation of the planned merger as more fully described in Note 6 or in the event that a Business Combination is not consummated, we will likely need to raise additional funds in order to meet the expenditures required for operating our business. Accordingly, the Company may not be able to obtain additional financing or raise additional capital to finance its ongoing operations. If the Company is unable to raise additional capital, it may be required to take additional measures to conserve liquidity, which could include, but not necessarily be limited to, curtailing operations, suspending the pursuit of a potential transaction and reducing overhead expenses. The Company cannot provide any assurance that new financing will be available to it on commercially acceptable terms, if at all. These conditions raise substantial doubt about the Company’s ability to continue as a going concern through November 22, 2021, the scheduled liquidation date. These financial statements do not include any adjustments relating to the recovery of the recorded assets or the classification of the liabilities that might be necessary should the Company be unable to continue as a going concern.

Summary of Significant Accounting Policies

2 Months Ended

9 Months Ended

12 Months Ended

Feb. 14, 2020

Sep. 30, 2020

Dec. 31, 2019

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

NOTE 2 — SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The financial statements of the Company are presented in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

Emerging Growth Company

Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Exchange Act) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that a company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such an election to opt out is irrevocable. The Company has elected not to opt out of such extended transition period which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company, as an emerging growth company, can adopt the new or revised standard at the time private companies adopt the new or revised standard.

This may make comparison of the Company’s financial statement with another public company which is neither an emerging growth company nor an emerging growth company which has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used.

Net Loss Per Common Share

The Company complies with accounting and disclosure requirements of ASC Topic 260, “Earnings Per Share.” Net loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding for the period, excluding shares of common stock subject to forfeiture. Net loss per common share is computed by dividing net gain/(loss) applicable to common stockholders by the weighted average number of common shares outstanding during the period, plus, to the extent dilutive, the incremental number of shares of common stock to settle warrants, as calculated using the treasury stock method. At February 14, 2020 and December 31, 2019, the Company did not have any dilutive securities and other contracts that could, potentially, be exercised or converted into common stock and then share in the earnings of the Company under the treasury stock method. As a result, diluted loss per common share is the same as basic loss per common share for the periods. In February 2020, the Company completed a stock split of 1 to 575 shares of Class B common stock, resulting in 5,750,000 shares of Class B common stock issued and outstanding. The financial statements have been retroactively adjusted to reflect the stock split for all periods presented.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash accounts in a financial institution, which, at times, may exceed the Federal Depository Insurance Coverage of $250,000. The Company has not experienced losses on these accounts and management believes the Company is not exposed to significant risks on such accounts.

Financial Instruments

The fair value of the Company’s assets and liabilities, which qualify as financial instruments under the FASB ASC 820, “Fair Value Measurements and Disclosures,” approximates the carrying amounts represented in the balance sheet, primarily due to their short-term nature.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires the Company’s management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Income Taxes

The Company is included in the consolidated tax return of B. Riley Financial the parent (the “Parent”). The Company calculates the provision for income taxes by using a “separate return” method. Under this method the Company is assumed to file a separate return with the tax authority, thereby reporting its taxable income or loss and paying the applicable tax to, or receiving the appropriate refund from, the Parent. The Company’s current provision is the amount of tax payable or refundable on the basis of a hypothetical, current year, separate return.

Any difference between the tax provision (or benefit) allocated to the Company under the separate return method and payments to be made to (or received from) the Parent for tax expense are treated as either dividends or capital contribution. Accordingly, the amount by which the Company’s tax liability under the separate return method exceeds the amount of tax liability ultimately settled as a result of using incremental expenses of the Parent is periodically settled as a capital contribution from the Parent to the Company.

The Company complies with the accounting and reporting requirements of ASC Topic 740 “Income Taxes,” which requires an asset and liability approach to financial accounting and reporting for income taxes. Deferred income tax assets and liabilities are computed for differences between the financial statement and tax bases of assets and liabilities that will result in future taxable or deductible amounts, based on enacted tax laws and rates applicable to the periods in which the differences are expected to affect taxable income. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized.

ASC Topic 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more-likely-than-not to be sustained upon examination by taxing authorities. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. As of February 14, 2020 and December 31, 2019, there were no unrecognized tax benefits and no amounts accrued for interest and penalties. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position.

The Company may be subject to potential examination by federal, state and city taxing authorities in the areas of income taxes since inception. These potential examinations may include questioning the timing and amount of deductions, the nexus of income among various tax jurisdictions and compliance with federal, state and city tax laws. The Company’s management does not expect that the total amount of unrecognized tax benefits will materially change over the next twelve months.

The provision for income taxes was deemed to be immaterial at December 31, 2019 and February 14, 2020.

Recent Accounting Pronouncements

Management does not believe that any recently issued, but not yet effective, accounting pronouncements, if currently adopted, would have a material effect on the Company’s financial statements.

NOTE 2 — SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The financial statements of the Company are presented in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Securities Exchange Act of 1934, as amended) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that a company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such an election to opt out is irrevocable. The Company has elected not to opt out of such extended transition period which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company, as an emerging growth company, can adopt the new or revised standard at the time private companies adopt the new or revised standard.

The Company’s unaudited condensed interim financial statements have been prepared in accordance with U.S. GAAP and the rules and regulations of the SEC for interim financial information and the instructions to Form 10-Q. Accordingly, the financial statements do not include all of the information and footnotes required by U.S. GAAP. In the opinion of management, all adjustments considered for a fair presentation have been included. Operating results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020 or any other period. The accompanying unaudited condensed interim financial statements should be read in conjunction with the Company’s audited financial statements and notes thereto included in the Company’s prospectus filed with the SEC on May 20, 2020, as well as the Company’s audited balance sheet statement and notes thereto included in the Company’s Form 8-K filed with the SEC on May 28, 2020.

Loss Per Common Share

Loss per share is computed by dividing net loss by the weighted average number of shares of common stock outstanding for the period. The Company applies the two-class method in calculating earnings per share. Shares of common stock subject to possible redemption at June 30, 2020, which are not currently redeemable and are not redeemable at fair value, have been excluded from the calculation of basic loss per share since such shares, if redeemed, only participate in their pro rata share of the Trust Account earnings. The Company has not considered the effect of warrants sold in the Public Offering and the Private Placement to purchase 9,075,000 shares of Class A common stock, in the calculation of diluted loss per share, since the exercise of the warrants is contingent upon the occurrence of future events. As a result, diluted loss per share is the same as basic loss per share for the periods presented. In February 2020, the Company completed a stock split of 1 to 575 shares of Class B common stock, resulting in 5,750,000 shares of Class B common stock issued and outstanding. The financial statements have been retroactively adjusted to reflect the stock split for all periods presented.

Reconciliation of Income (Loss) Per Common Share

The Company’s net loss is adjusted for the portion of income that is attributable to shares of common stock subject to possible redemption, as these shares only participate in the earnings of the Trust Account and not the income or losses of the Company. Accordingly, basic and diluted loss per share is calculated as follows:

	Three Months Ended September 30, 2020			Three Months Ended September 30, 2019		Nine Months Ended September 30, 2020			Period from June 3, 2019 (Inception) through September 30, 2019
Net loss	$	(1,961,854	)	$	—	$	(2,047,597	)	$	—
Less: Loss attributable to common stock subject to possible redemption		(31,646	)		—		(41,955	)		—

Adjusted net loss	$	(1,993,500	)	$	—	$	(2,089,552	)	$	—

Weighted average shares outstanding, basic and diluted		5,450,881			5,000,000		7,654,134			5,000,000

Basic and diluter loss per common share	$	(0.37	)	$	—	$	(0.27	)	$	—

Cash and Cash Equivalents

The Company considers all short-term investments with an original maturity date of three months or less when purchased to be cash equivalents. The Company did not have any cash equivalents as of December 31, 2019.

Class A Common Stock Subject To Possible Redemption

At discussed in Note 1, all of the 17,500,000 shares of Class A common stock sold as part of the Units in the Public Offering contain a redemption feature. In accordance with FASB ASC 480, “Distinguishing Liabilities From Equity,” redemption provisions not solely within the control of the Company require the security to be classified outside of permanent equity. Ordinary liquidation events, which involve the redemption and liquidation of all of the entity’s equity instruments, are excluded from the provisions of FASB ASC 480. Although the Company has not specified a maximum redemption threshold, its amended and restated certificate of incorporation provides that in no event will the Company redeem its public shares in an amount that would cause its net tangible assets to be less than $5,000,001.

Concentration of Credit Risk

Fair Value of Financial Instruments

The fair value of the Company’s assets and liabilities, which qualify as financial instruments under ASC Topic 820, “Fair Value Measurement,” approximates the carrying amounts represented in the balance sheet, primarily due to their short-term nature.

Use of Estimates

Offering Costs

The Company complies with the requirements of the FASB ASC 340-10-S99-1 and SEC Staff Accounting Bulletin Topic 5A — “Expenses of Offering.” The total offering costs incurred by the Company in connection with the Public Offering was $476,189. These costs and the underwriter discount, of $3,500,000, were charged to capital upon completion of the Public Offering on May 22, 2020.

Income Taxes

Prior to the change in ownership on May 22, 2020 as a result of the Public Offering, the Company was included in the consolidated tax return of B. Riley Financial (the “Parent”). During this period, the Company calculated the provision for income taxes by using a “separate return” method. Under this method the Company is assumed to file a separate return with the tax authority, thereby reporting its taxable income or loss and paying the applicable tax to, or receiving the appropriate refund from, the Parent. The current provision was the amount of tax payable or refundable on the basis of a hypothetical, current year, separate return. Following changes in ownership on May 22, 2020, the Company deconsolidated from the Parent for tax purposes. Beginning May 22, 2020, the Company files separate corporate federal and state and local income tax returns.

Any difference between the tax provision (or benefit) allocated to the Company under the separate return method and payments to be made by (or received from) the Parent for tax expense are treated as either dividends or capital contribution. Accordingly, the amount by which the Company’s tax liability under the separate return method exceeds the amount of tax liability ultimately settled as a result of using incremental expenses of the Parent is periodically settled as a capital contribution from the Parent to the Company.

ASC Topic 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. As of September 30, 2020 and December 31, 2019, there were no unrecognized tax benefits and no amounts accrued for interest and penalties. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position.

The Company may be subject to potential examination by federal, state and city taxing authorities in the areas of income taxes. These potential examinations may include questioning the timing and amount of deductions, the nexus of income among various tax jurisdictions and compliance with federal, state and city tax laws. The Company’s management does not expect that the total amount of unrecognized tax benefits will materially change over the next twelve months.

There was no provision for income taxes for the three and nine months ended September 30, 2020 and for the three months ended September 30, 2019 and the period from June 3, 2019 (Inception) through September 30, 2019.

Unrecognized Tax Benefits

The Company recognizes tax positions in its financial statements only when it is more likely than not that the position will be sustained on examination by the relevant taxing authority based on the technical merits of the position. A position that meets this standard is measured at the largest amount of benefit that will more likely than not be realized on settlement. A liability is established for differences between positions taken in a tax return and amounts recognized in the financial statements. There were no unrecognized tax benefits as of September 30, 2020. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. No amounts were accrued for interest expense and penalties related to income tax matters as of September 30, 2020 and December 31, 2019. The Company is subject to income tax examinations by major taxing authorities since inception.

Recent Accounting Standards

Management does not believe that any recently issued, but not yet effective, accounting standards updates, if currently adopted, would have a material effect on the Company’s financial statements.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

1. Nature of Operations and Summary of Significant Accounting Policies

Nature of Operations

Eos Energy Storage, LLC ("Eos" or the "Company") is a United States based entity that was created on April 24, 2008 under the Delaware State laws. Eos designs, develops, manufactures, and sells innovative energy storage solutions for the electric utilities, and commercial and industrial end users. Eos has developed and has received patents on an innovative battery design relying on a unique zinc oxidation /reduction cycle to generate output current and to recharge. The Battery Management System ("BMS") software uses proprietary Eos-developed algorithms and includes ambient and battery temperature sensors, as well as voltage and current sensors for the strings and the system. Eos and their partners focus on a collaborative approach to jointly develop and sell safe, reliable, long-lasting low-cost turn-key alternating current ("AC") integrated systems using Eos's Aurora direct current ("DC") Battery System. The Company is also an investor in an unconsolidated joint venture ("JV") which has the exclusive rights to manufacture the DC Battery Systems integrated with the BMS for DC Battery Systems that are sold and delivered in North America, subject to meeting certain performance targets. The Company's major markets are integration of battery storage with solar that is connected to the utility power grid or the customer's solar system that is not connected to the utility power grid, battery storage systems to be used by utilities to relieve congestion in the power grids and battery storage systems to assist commercial and industrial customers in reducing their peak energy usage or participating in the utilities ancillary and demand response markets. The location of the Company's major markets are seen in North America, Europe, Africa, and Asia.

Liquidity and Going Concern

The Company is in the development stage of its lifecycle and, as such, has no significant history of revenue generating activities. Accordingly, the Company has incurred significant recurring losses, negative working capital, and net operating cash outflows from operations since inception, which is attributable to its higher operating costs relative to its lack of revenue base. Operating expenses consist primarily of costs related to the Company's sales of their product along with the associated research and development costs, as well as other recurring general and administrative expenses, such as professional fees, rent, and utilities. While management and the Company's Board of Directors anticipate the Company will eventually exit the development stage by reaching a scale of profitability through the sale of Second Generation Aurora DC Battery Systems ("Gen 2.3") and other complimentary products, they believe the current stage of the Company's lifecycle justifies continued investment in the development and launch of product with outside capital at the expense of short-term profitability. Accordingly, the Company anticipates continuing to incur significant losses, negative working capital, and net operating cash outflows from operations for the foreseeable future to fund its obligations as they become due, which includes necessary funding to scale up of the Company's operations to allow for the delivery of order backlog and additional order opportunities for its Gen 2.3 Battery System, continued investment in research and development, and commitments associated with the Company's unconsolidated joint venture (see Note 6). In addition, the materially adverse impact that COVID-19 has had on the global economy could deteriorate demand for the Company's Gen 2.3 Battery System or impair its ability to continue to invest in research and development and its unconsolidated joint venture if the global pandemic worsens or anticipated vaccines and therapeutic remedies do not mitigate the spread of the disease.

As of September 30, 2020, Eos had total assets of $22,293, which includes total cash and cash equivalents of $6,534, total liabilities of $132,469, which includes the total amounts owed on the Company's outstanding convertible notes payable of $108,353 that are due and payable on demand by the noteholders (see Note 11), contingently redeemable preferred units of $118,624 and a total members' (deficit) of ($228,800), which is primarily attributable to the significant recurring losses the Company has accumulated since inception. The Company has historically relied on outside capital to fund its cost structure and expects this reliance to continue for the foreseeable future until the Company reaches a scale of profitability through its planned revenue generating activities. However, as of the date of issuance of these financial statements, the Company did not have sufficient capital to support its current cost structure, which includes the total amounts owed on the Company's outstanding convertible notes, for one year after the date the accompanying unaudited interim condensed financial statements were issued.

On September 7, 2020, the Company entered into a merger agreement to merge with B. Riley Principal Merger Corp. II ("BMRG II"). BMRG II is a special acquisition company ("SPAC") incorporated for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (the "SPAC transaction"). The SPAC transaction is currently expected to close in November 2020 and would allow all holders of the Company's equity and equity-linked securities to receive common stock of the continuing public company, BMRG II. Accordingly, as part of the closing of the SPAC transaction, the Company currently expects substantially all the total amounts owed on the Company's outstanding convertible notes will be converted into shares of the continuing public company. The merger would result in a net increase in cash to the Company of between approximately $97.8 million, assuming maximum shareholder redemptions permitted under the Business Combination Agreement, and $204.6 million, assuming minimum shareholder redemption. Management plans to use these proceeds, among other things, to fund the Company's obligations as they become due. While management believes they will be able to close the SPAC transaction in the fourth quarter of 2020, no assurance can be provided that such transaction will close or on terms that are acceptable to the Company. If the Company is unable to close the SPAC transaction, management plans to obtain additional outside capital to fund the Company's current cost structure through the issuance of Series E Preferred shares and modify the terms of the Company's outstanding convertible notes to, among other things, extend the current amounts owed to future periods. While management believes they would be able to issue Series E Preferred shares and modify the terms of the Company's outstanding convertible notes in the event the SPAC transaction fails to close, no assurance can be provided that such issuance and modification will occur or on terms that are acceptable to the Company.

Management believes these uncertainties raise substantial doubt about the Company's ability to continue as a going concern. If the Company is unable to close the SPAC transaction, or issue Series E Preferred shares and modify the terms of the Company's outstanding convertible notes, management may have to seek other strategic alternatives, which could include, among other things, a sale of the Company, filing of insolvency, or a cessation of the Company's operations.

The accompanying unaudited interim condensed financial statements have been prepared on the basis that the Company will continue to operate as a going-concern, which contemplates the Company will be able to realize assets and settle liabilities and commitments in the normal course of business for the foreseeable future. The accompanying unaudited interim condensed financial statements do not include any adjustments that may result from the outcome of these uncertainties.

Basis of Presentation

The financial statements include the accounts of the Company and have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP").

Deferred Transaction Costs

Deferred transaction costs of $2,386 at September 30, 2020 represent expenses paid or payable in connection with the proposed business combination with B. Riley Principal Merger Corp II. These costs include, but are not limited to, attorneys' fees, accountants' fees and other professional services associated with the proposed transaction.

Concentration of Credit Risk

Eos maintains cash balances at FDIC-insured institutions. However, the FDIC limits may be exceeded at times. The Company has not experienced any losses on such accounts.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

The most significant estimates in the accompanying condensed financial statements include the valuation of derivatives, the relative fair value allocation of Phase II bridge financing proceeds, the valuation of inventory, and estimated lives used for depreciation and amortization purposes.

Risks and Uncertainties

Eos holds several product patents, which if infringed upon, could result in significant expenses to defend. If Eos is unable to protect its intellectual property, it could have a significant impact on operations.

Revenue from Contracts with Customers

Revenue is earned from the sales, installation, and commissioning of energy storage systems and is derived from customer contracts. Revenue is recognized in an amount that reflects the consideration to which the Company expects to be entitled in exchange for transferring the promised goods and/or services to the customer, when or as the Company's performance obligations are satisfied. For product sales of energy storage systems, the Company's performance obligations are satisfied at the point in time when the customer obtains control of the system, which is either upon delivery of the goods at the customer's designated location or upon the customer's acceptance of the product after commissioning and testing at the customer's site, depending on the specific terms of the respective contract with the customer. In addition, the corresponding installation and commissioning services related to the systems are performance obligations satisfied over time as the respective services are performed, based on an input measure of progress as labor costs relating to the installation and commissioning services are incurred. Further, extended warranties are offered by the Company and are identified as performance obligations that are satisfied over time, based on a time-elapsed measure of progress resulting in a ratable recognition of revenue over the respective warranty period. Payment terms generally include advance payments to reserve capacity and/or upon issuance of the customer's purchase order, shipment readiness, with the remainder upon delivery and commissioning of the system. Shipping and handling costs are included in cost of sales. Sales tax collected from customers are recorded on a net basis and therefore, not included in revenue. Sales tax is recorded as a liability (payable) until remitted to governmental authorities.

The Company may enter into sales contracts that provide for performance obligations in addition to the sale of the product, including performance guarantees and service obligations. Under these sales contracts, the transaction price is allocated to the various performance obligations based on the relative stand-alone selling prices of the promised goods and services. When the stand-alone selling price is not observable, revenue related to service type warranties is determined based on a best estimate of selling price using cost plus a reasonable margin and is recognized ratably over the period of performance.

Royalty Revenue

The Company receives sales-based royalty payments related to the licensing of intellectual property to the Company's JV. This represents a performance obligation that is satisfied over time as the licensee accesses the intellectual property by producing and selling products. The Company recognizes royalty revenues when the licensee sells products to third parties.

Product Warranty

Warranty obligations are incurred in connection with the sale of the Company's products. The Company generally provides a standard warranty for a period of one to two years, commencing upon commissioning. Costs to provide for warranty obligations are estimated and recorded as a liability at the time of recording the sale. Extended warranties are identified as performance obligations in the Company's contracts with customers, and are discussed as part of revenue from contracts with customers. Costs incurred in satisfying the Company's performance obligations with respect to extended warranties are recognized as expenses when incurred.

1. Nature of Operations and Summary of Significant Accounting Policies

Nature of Operations

Eos Energy Storage, LLC (“Eos” or the “Company”) is a United States based entity that was created on April 24, 2008 under the Delaware State laws. Eos designs, develops, manufactures, and sells innovative energy storage solutions for the electric utilities, and commercial and industrial end users. Eos has developed and has received patents on an innovative battery design relying on a unique zinc oxidation /reduction cycle to generate output current and to recharge. The Battery Management System (“BMS”) software uses proprietary Eos-developed algorithms and includes ambient and battery temperature sensors, as well as voltage and current sensors for the strings and the system. Eos and their partners focus on a collaborative approach to jointly develop and sell safe, reliable, long-lasting low-cost turn-key alternating current (“AC”) integrated systems using Eos’s Aurora direct current (“DC”) Battery System. The Company is also an investor in an unconsolidated joint venture (“JV”) which has the exclusive rights to manufacture the DC Battery Systems integrated with the BMS for DC Battery Systems that are sold and delivered in North America, subject to meeting certain performance targets. The Company’s major markets are integration of battery storage with solar that is connected to the utility power grid or the customer’s solar system that is not connected to the utility power grid, battery storage systems to be used by utilities to relieve congestion in the power grids and battery storage systems to assist commercial and industrial customers in reducing their peak energy usage or participating in the utilities ancillary and demand response markets. The location of the Company’s major markets are seen in North America, Europe, Africa, and Asia.

Liquidity and Going Concern

The Company’s is in the development stage of its lifecycle and, as such, has no significant history of revenue generating activities. Accordingly, the Company has incurred significant recurring losses, negative working capital, and net operating cash outflows from operations since inception, which is attributable to its higher operating costs relative to its lack of revenue base. Operating expenses consist primarily of costs related to the Company’s sales of their product along with the associated research and development costs, as well as other recurring general and administrative expenses, such as professional fees, rent, and utilities. While management and the Company’s Board of Directors anticipate the Company will eventually exit the development stage by reaching a scale of profitability through the sale of Second Generation Aurora DC Battery Systems (“Gen 2.3”) and other complimentary products, they believe the current stage of the Company’s lifecycle justifies continued investment in the development and launch of product with outside capital at the expense of short-term profitability. Accordingly, the Company anticipates continuing to incur significant losses, negative working capital, and net operating cash outflows from operations for the foreseeable future to fund its obligations as they become due, which includes necessary funding to scale up of the Company’s operations to allow for the delivery of order backlog and additional order opportunities for its Gen 2.3 Battery System, continued investment in research and development, and commitments associated with the Company’s unconsolidated joint venture (see Note 6). In addition, as disclosed in Note 15, the materially adverse impact that COVID-19 has had on the global economy could deteriorate demand for the Company’s Gen 2.3 Battery System or impair its ability to continue to invest in research and development and its unconsolidated joint venture if the global pandemic worsens or anticipated vaccines and therapeutic remedies do not mitigate the spread of the disease.

As of December 31, 2019, Eos had total assets of $13,057, which includes total cash and cash equivalents of $862, total liabilities of $87,414, which includes the total amounts owed on the Company’s outstanding convertible notes payable of $76,559 that are due and payable on demand by the noteholders (see Note 11), contingently redeemable preferred units of $109,365 and a total members’ (deficit) of ($183,722), which is primarily attributable to the significant recurring losses the Company has accumulated since inception. The Company has historically relied on outside capital to fund its cost structure and expects this reliance to continue for the foreseeable future until the Company reaches a scale of profitability through its planned revenue generating activities. However, as of the date the accompanying financial statements were issued, the Company did not have sufficient capital to support its current cost structure, which includes the total amounts owed on the Company’s outstanding convertible notes, for one year after the date the accompanying financial statements were issued.

As disclosed in Note 15, the Company entered into a letter of intent dated June 24, 2020 to merge with B. Riley Principal Merger Corp. II (“BMRG II”). BMRG II is a special acquisition company (“SPAC”) incorporated for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (the “SPAC transaction”). The SPAC transaction is currently expected to close in the fourth quarter of 2020 and would allow all holders of the Company’s equity and equity-linked securities to receive a combination of common stock of the continuing public company, which will be a wholly owned subsidiary of BMRG II. Accordingly, as part of the closing of the SPAC transaction, the Company currently expects substantially all the total amounts owed on the Company’s outstanding convertible notes will be converted into shares of the continuing public company. The merger would result in a net increase in cash to the Company of between approximately $66.4 million, assuming maximum shareholder redemptions permitted under the Business Combination Agreement, and $212.3 million, assuming minimum shareholder redemption, for which management plans to use to, among other things, fund the Company’s obligations as they become due. While management believes they will be able to close the SPAC transaction in October 2020, no assurance can be provided that such transaction will close or on terms that are acceptable to the Company. If the Company is unable to close the SPAC transaction, management plans to obtain additional outside capital to fund the Company’s current cost structure through the issuance of Series E Preferred shares and modify the terms of the Company’s outstanding convertible notes to, among other things, extend the current amounts owed to future periods. While management believes they would be able to issue Series E Preferred shares and modify the terms of the Company’s outstanding convertible notes in the event the SPAC transaction fails to close, no assurance can be provided that such issuance and modification will occur or on terms that are acceptable to the Company.

Management believes these uncertainties raise substantial doubt about the Company’s ability to continue as a going concern. If the Company is unable to close the SPAC transaction, or issue Series E Preferred shares and modify the terms of the Company’s outstanding convertible notes, management may have to seek other strategic alternatives, which could include, among other things, a sale of the Company, filing of insolvency, or a cessation of the Company’s operations.

The accompanying financial statements have been prepared on the basis that the Company will continue to operate as a going-concern, which contemplates the Company will be able to realize assets and settle liabilities and commitments in the normal course of business for the foreseeable future. The accompanying financial statements do not include any adjustments that may result from the outcome of these uncertainties.

Basis of Presentation

The financial statements include the accounts of the Company and have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).

Cash and Cash Equivalents

Cash and cash equivalents include cash and highly liquid investments purchased with original maturities of three months or less.

Concentration of Credit Risk

Eos maintains cash balances at FDIC-insured institutions However, the FDIC limits may be exceeded at times. The Company has not experienced any losses on such accounts.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Income Taxes and Deferred Taxes

Eos complies with the accounting and reporting requirements of FASB ASC Topic 740, Income Taxes (ASC 740). Income taxes are computed under the asset and liability method reflecting both current and deferred taxes, which reflect the tax impact of all events included in the financial statements. The balance sheet approach (i) reflects a current tax liability or asset recognized for estimated taxes payable or refundable on tax returns for the current and prior years, (ii) reflects a deferred tax liability or asset recognized for the estimated future tax effects attributable to temporary differences and carryforwards, (iii) measures current and deferred tax liabilities and assets using the enacted tax rate of which the effects of future changes in tax laws or rates are not anticipated, and (iv) reduces deferred tax assets, if necessary, by the amount of any tax benefits that, based on available evidence, are not expected to be realized.

ASC 740 prescribes a recognition threshold and a measurement attribute for financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. Eos recognizes deferred tax assets only to the extent that management concludes these assets are more-likely-than-not to be realized. Significant judgement is required in assessing and estimating the more-likely-than-not tax consequences of the events included in the financial statements. Management considers all available positive and negative evidence, including future reversals of existing temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations.

Eos recognizes accrued interest and penalties related to unrecognized tax benefits, if any, as income tax expense. Eos records uncertain tax positions in accordance with ASC 740 on the basis of a two-step process in which (i) management determines whether it is more-likely-than-not that the tax position will be sustained on the technical merits of the position and (ii) for those tax positions that meet the more-likely-than-not recognition threshold, Eos recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. The Company has determined that there are no uncertain income tax positions at December 31, 2018 and December 31, 2019 that do not meet the more-likely-than-not threshold under ASC 740. See Note 9 for further information.

Impairment of Long — Lived Assets

The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. An assessment is performed to determine whether the depreciation and amortization of long-lived assets over their remaining lives can be recovered through projected undiscounted future cash flows. The amount of any long-lived asset impairment is measured based on fair value and is charged to operations in the period in which long-lived assets impairment is determined by management. For the years ended December 31, 2019 and 2018, the Company recorded impairment expenses of $1,590 and $1,441, respectively, primarily related to obsolete equipment relating to its prior generation battery and is reflected in cost of goods sold, research and development expenses and general and administrative expenses in the Statements of Operations.

Intangible Assets

Intangible assets are stated at their historical cost and amortized on a straight-line basis over their expected useful lives.

Property and Equipment

Equipment is stated at cost, less accumulated depreciation. Depreciation is computed on the straight-line method over the estimate useful lives of the assets. Leasehold improvements are amortized on the straight-line method over the shorter of the estimated useful lives of the improvements or the life of the lease. Maintenance and repairs expenditures are expensed as incurred. Expenditures which significantly improve or extend the life of an asset are capitalized.

Risks and Uncertainties

Revenue from Contracts with Customers

Revenue is earned from the sales, installation, and commissioning of energy storage systems and is derived from customer contracts. Revenue is recognized in an amount that reflects the consideration to which the Company expects to be entitled in exchange for transferring the promised goods and/or services to the customer, when or as the Company’s performance obligations are satisfied. For product sales of energy storage systems, the Company’s performance obligations are satisfied at the point in time when the customer obtains control of the system, which is either upon delivery of the goods at the customer’s designated location or upon the customer’s acceptance of the product after commissioning and testing at the customer’s site, depending on the specific terms of the respective contract with the customer. In addition, the corresponding installation and commissioning services related to the systems are performance obligations satisfied over time as the respective services are performed, based on an input measure of progress as labor costs relating to the installation and commissioning services are incurred. Further, extended warranties are offered by the Company and are identified as performance obligations that are satisfied over time, based on a time-elapsed measure of progress resulting in a ratable recognition of revenue over the respective warranty period. Payment terms generally include advance payments to reserve capacity and/or upon issuance of the customer’s purchase order, shipment readiness, with the remainder upon delivery and commissioning of the system. Shipping and handling costs are included in cost of sales. Sales tax collected from customers are recorded on a net basis and therefore, not included in revenue. Sales tax is recorded as a liability (payable) until remitted to governmental authorities.

The Company may enter into sales contracts that provide for performance obligations in addition to the sale of the product, including performance guarantees and service obligations. Under these sales contracts, transaction price is allocated to the various performance obligation based on the relative stand-alone selling prices of the promised goods and services. When the stand-alone selling price is not observable, revenue related to service type warranties is determined based on a best estimate of selling price using cost plus a reasonable margin and is recognized ratably over the period of performance.

Royalty Revenue

The Company receives sales-based royalty payments related to the licensing of intellectual property to the Company’s JV. This represents a performance obligation that is satisfied over time as the licensee accesses the intellectual property by producing and selling products. The Company recognizes royalty revenues when the licensee sells products to third parties.

Product Warranty

Warranty obligations are incurred in connection with the sale of the Company’s products. The Company generally provides a standard warranty for a period of one to two years, commencing upon commissioning. Costs to provide for warranty obligations are estimated and recorded as a liability at the time of recording the sale. Extended warranties are identified as performance obligations in the Company’s contracts with customers, and are discussed as part of revenue from contracts with customers. Costs incurred in satisfying the Company’s performance obligations with respect to extended warranties are recognized as expenses when incurred.

Government Grants

The Company records grants received or receivable from government agencies as an offset to the related costs for which the grants are intended to compensate the Company. The costs of satisfying the Company’s obligations under the respective grant agreements are recognized as expense when incurred. Once the expenses are approved by the government agencies the Company records the grant receivable and related grant revenue.

Research and Development Expenses

Research and development costs are expensed as incurred, which include materials, supplies, salaries, benefits and other costs related to research, development and testing of products.

Rent Expense

The Company records rent expense on a straight-line basis based on the total minimum lease payments over the term of the lease. Differences between cash paid for lease payments and rent expense are recorded as Deferred rent on the Balance Sheets.

Accounts Receivable

The Company evaluates the creditworthiness of its customers. If the collection of any specific receivable is doubtful, an allowance is recorded in the allowance for doubtful accounts. As of December 31, 2019 and 2018, no such allowances have been recorded. The Company had no accounts receivable as of December 31, 2019 and 2018.

Inventory

Inventories are stated at the lower of cost, which approximates cost determined on a first-in, first-out basis, or net realizable value. The Company records inventory when it takes delivery and title to the product according to the terms of each supply contract.

The Company evaluates its ending inventories for excess quantities and obsolescence. Inventories that management considers excess or obsolete are reserved. Management considers forecasted demand in relation to the inventory on hand, competitiveness of product offerings, market conditions and product life cycles when determining excess and obsolescence and net realizable value adjustments. Once inventory is written down and a new cost basis is established, it is not written back up if demand increases.

Investment in unconsolidated joint venture

The Company accounts for its investment in its unconsolidated joint venture using the equity method of accounting as it has been determined that the Company has the ability to exercise significant influence and is not otherwise required to consolidate. All significant decisions require unanimous consent of both joint venture members. Under the equity method, the investment is initially recorded at cost and subsequently adjusted for the Company’s share of equity in the joint venture’s income or loss.

The Company reviews its investments for other-than-temporary impairment whenever events or changes in business circumstances indicate that the carrying value of the investment may not be fully recoverable. Investments identified as having an indication of impairment are subject to further analysis to determine if the impairment is other than temporary and to estimate the investment’s fair value.

Stock-Based Compensation

Stock-based compensation is estimated at the grant date based on the fair value of the award and is recognized as expense over the requisite service period of the award. The Company uses the Black-Scholes option pricing model to estimate the fair value of awards, and generally these awards only have service conditions. The Company recognizes compensation cost on a straight-line basis over the requisite service/vesting period. Determining the appropriate fair value model and related assumptions requires judgment, including estimating volatility of the Company’s common stock and expected terms. The expected volatility rates are estimated based on historical and implied volatilities of comparable publicly traded companies. The expected term represents the average time that the options that vest are expected to be outstanding based on the vesting provisions, which is determined through the simplified method, since the Company does not have sufficient historical experience regarding the exercise of options. The Company has elected to recognize forfeitures as incurred.

Segments

The Company’s chief operating decision-maker (“CODM”) is its Chief Executive Officer and President. Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by its CODM in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance. As such, the Company has determined that it operates in one operating and one reportable segment.

Fair Value of Financial Instruments

The Company’s financial instruments consist of cash and cash equivalents, accounts receivable, accounts payable, and notes payable — related party.

Accounting standards establish a hierarchy which prioritizes the inputs to valuation techniques used to measure fair value into three levels. The fair value hierarchy gives the highest priority to quoted market prices (unadjusted) in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

Accounting standards require financial assets and liabilities to be classified based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of the fair value of assets and liabilities and their placement within the fair value hierarchy levels.

The carrying value of cash and cash equivalents, grants receivable, and accounts payable are considered to be representative of their fair value due to the short maturity of these instruments. The fair value of both the Company’s convertible notes payable — related party (the “Convertible Notes”) and the embedded derivative liability are classified within Level 3 of the fair value hierarchy.

The estimated future cash flows of the Convertible Notes were discounted using a discount rate derived from an appropriate risk-free interest rate yield curve and credit spread, and the estimated repayment date. As the Company does not have a market observable credit spread, the Company obtained a range of potential credit spreads available from market observable information on entities with a comparable credit risk. As of December 31, 2019, the estimated fair value of the convertible notes payable — related party is approximately $65,942, as compared to the carrying value of approximately $76,559.

The fair value of the embedded derivatives are determined using valuation techniques that require the use of assumptions concerning the amount and timing of future cash flows, discount rates, and probability of future events and redemption dates that are beyond management’s control. As of December 31, 2019, the fair value of the embedded derivative liability was $1,618.

As of December 31, 2018, the carrying value of the Company’s notes payable and convertible notes payable — related party of $1,000 and $2,350, respectively, approximate their fair values.

Refer to Note 11 for further discussion of the convertible notes payable — related party and the embedded derivatives.

Recent Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The ASU is effective for private companies for annual reporting periods beginning after December 15, 2021 and early adoption is permitted. The ASU will require lessees to report most leases as assets and liabilities on the balance sheet. The Company is currently evaluating the potential impact of adopting this guidance on its financial statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments in ASU 2016-13 will provide more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The ASU is effective for annual reporting periods beginning after December 15, 2022. The Company is currently evaluating the potential impact of adopting this guidance on its financial statements.

Public Offering	2 Months Ended
Public Offering	Feb. 14, 2020
Notes to Financial Statements
PUBLIC OFFERING	NOTE 3 — PUBLIC OFFERING Pursuant to the Proposed Offering, the Company intends to offer for sale 17,500,000 Units at an offering price of $10.00 per Unit. The Sponsor will subscribe to purchase an aggregate of 650,000 Units (or 728,750 Units if the underwriters’ over-allotment option is exercised in full — see below) at a price of $10.00 per Private Placement Unit in a private placement that will close simultaneously with the Proposed Offering. Each Unit consists of one share of the Company’s Class A common stock, $0.0001 par value, and one-half of one redeemable warrant, with each whole warrant exercisable for one share of Class A common stock (each, a “Warrant” and, collectively, the “Warrants” and, with respect to the warrants underlying the Private Placement Units, the “Private Placement Warrants”). One Warrant entitles the holder thereof to purchase one whole share of Class A common stock at a price of $11.50 per share. The Company has also granted the underwriters a 45-day option to purchase on a pro rata basis up to 2,625,000 additional Units at the initial public offering price less the underwriting discounts and commissions. The option may be exercised only to cover any over-allotments of Units. The Company expects to pay underwriting commissions equal to 2.0% of the gross proceeds of the Proposed Offering at the time of the Proposed Offering. Business Combination Marketing Agreement The Company will engage B. Riley Securities, Inc. as advisors in connection with its Initial Business Combination to assist it in arranging meetings with its stockholders to discuss a potential business combination and the target business’ attributes, introduce it to potential investors that may be interested in purchasing its securities, assist it in obtaining stockholder approval for its Initial Business Combination and assist it with the preparation of press releases and public filings in connection with the Initial Business Combination. The Company will pay B. Riley Securities, Inc. for such services upon the consummation of the Initial Business Combination a cash fee in an amount equal to 3.5% of the gross proceeds of the Proposed Offering (exclusive of any applicable finders’ fees which might become payable) ($6,125,000 or up to $7,043,750 if the underwriters’ over-allotment option is exercised in full). Pursuant to the terms of the business combination marketing agreement, no fee will be due if the Company does not complete an Initial Business Combination.

Revenue Recognition

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Revenue Recognition

2. Revenue Recognition

Contract Balances

The following table provides information about contract liabilities from contracts with customers:

		September 30, 2020			December 31, 2019			September 30, 2019			December 31, 2018
Contract Liabilities		$	310		$	300		$	817		$	718

Contract liabilities primarily relate to advance consideration received from customers and deferred revenue for which transfer of control occurs, and therefore revenue is recognized, as services are provided. Contract balances are reported in a net contract asset or liability position on a contract-by-contract basis at the end of each reporting period.

During the nine months ended September 30, 2020, contract liabilities increased $10. The Company recognized $0 of revenue during the nine months ended September 30, 2020 that was included in the contract liability balance at the beginning of the period.

During the nine months ended September 30, 2019, contract liabilities increased $99. The Company recognized $0 of revenue during the nine months ended September 30, 2019 that was included in the contract liability balance at the beginning of the period.

Transaction Price Allocated to Remaining Performance Obligations

The following table includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied) at September 30, 2020:

September 30, 2020		2020			2021			2022			2023			Thereafter
Product Revenue		$	310		$	—		$	—		$	—		$	—

2. Revenue Recognition

Contract Balances

The following table provides information about contract liabilities from contracts with customers:

		September 30, 2020			December 31, 2019			September 30, 2019			December 31, 2018
Contract Liabilities		$	310		$	300		$	817		$	718

Transaction Price Allocated to Remaining Performance Obligations

The following table includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied) at September 30, 2020:

September 30, 2020		2020			2021			2022			2023			Thereafter
Product Revenue		$	310		$	—		$	—		$	—		$	—

Inventory	9 Months Ended	12 Months Ended
Inventory	Sep. 30, 2020	Dec. 31, 2019
EOS ENERGY STORAGE, LLC [Member]
Inventory	3. Inventory As of September 30, 2020, and December 31, 2019, we had inventories of $78 and $0, respectively.	3. Inventory As of December 31, 2019 and 2018, we had inventories of $0 and $801, which was comprised of raw materials.

Property and Equipment

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Property and Equipment

4. Property and Equipment

As of September 30, 2020 and December 31, 2019, property and equipment consisted of the following:

	2020			2019			Useful lives
Equipment	$	7,039		$	5,910		5 – 10 years
Capital lease		201			201		5 years
Furniture		176			125		5 – 10 years
Leasehold Improvements		2,732			2,732		Lesser of useful life/remaining lease
Tooling		588			150		2 – 3 years
Total		10,736			9,118
Less: Accumulated Depreciation and Amortization		(4,919	)		(3,802	)
	$	5,817		$	5,316

Depreciation and amortization expense related to property and equipment was $1,112 and $1,740 during the nine months ended September 30, 2020 and 2019, respectively.

4. Property and Equipment

As of December 31, 2019 and 2018, property and equipment consisted of the following:

	2019			2018			Useful lives
Equipment	$	5,910		$	9,438		5 – 10 years
Capital lease		201			225		5 years
Furniture		125			186		5 – 10 years
Leasehold Improvements		2,732			3,130		Lesser of useful life/remaining lease
Construction in progress		—			50
Tooling		150			907		2 – 3 years
Total		9,118			13,936
Less: Accumulated Depreciation and Amortization		(3,802	)		(7,394	)
	$	5,316		$	6,542

Depreciation and amortization expense related to property and equipment was $2,083 and $2,417, during the years ended December 31, 2019 and 2018, respectively.

Intangible Assets

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Intangible Assets

5. Intangible Assets

Intangible assets consisted of various patents valued at $400, which represents the cost to acquire the patents. These patents are determined to have useful lives and are amortized into the results of operations over ten years. During the nine months ended September 30, 2020 and 2019, the Company recorded amortization expenses of $30 for each period related to patents.

Estimated future amortization expense of intangible assets as of September 30, 2020 are as follows:

Remainder of 2020	$	10
2021		40
2022		40
2023		40
2024		40
Thereafter		160
	$	330

5. Intangible Assets

Intangible assets consisted of various patents valued at $400, which represents the cost to acquire the patents. These patents are determined to have useful lives and are amortized into the results of operations over ten years. During the years ended December 31, 2019 and 2018, the Company recorded amortization expenses of $40 and $0, respectively, related to patents.

Estimated future amortization expense of intangible assets as of December 31, 2019 are as follows:

2020	$	40
2021		40
2022		40
2023		40
2024		40
Thereafter		160
	$	360

Stockholders' Equity	2 Months Ended	9 Months Ended
Stockholders' Equity	Feb. 14, 2020	Sep. 30, 2020
Equity [Abstract]
STOCKHOLDERS’ EQUITY	NOTE 5 — STOCKHOLDER’S DEFICIT Common Stock The authorized common stock of the Company includes up to 100,000,000 shares of Class A common stock and 25,000,000 shares of Class B common stock. If the Company enters into an Initial Business Combination, it may (depending on the terms of such an Initial Business Combination) be required to increase the number of shares of Class A common stock which the Company is authorized to issue at the same time as the Company’s stockholders vote on the Initial Business Combination to the extent the Company seeks stockholder approval in connection with the Initial Business Combination. Holders of the Company’s common stock are entitled to one vote for each share of common stock. At February 14, 2020 and December 31, 2019, there were 5,750,000 shares of Class B common stock issued and outstanding (up to 656,250 shares of which are subject to forfeiture depending on the extent to which the underwriters’ over-allotment option is exercised) and no shares of Class A common stock issued and outstanding. Preferred Stock The Company is authorized to issue 1,000,000 shares of preferred stock with such designations, voting and other rights and preferences as may be determined from time to time by the Company’s board of directors. At February 14, 2020 and December 31, 2019, there were no shares of preferred stock issued or outstanding. Warrants Warrants may only be exercised for a whole number of shares. No fractional Warrants will be issued upon separation of the Units and only whole Warrants will trade. The Warrants will become exercisable on the later of (a) 30 days after the completion of the Initial Business Combination or (b) 12 months from the closing of the Proposed Offering; provided in each case that the Company has an effective registration statement under the Securities Act covering the shares of Class A common stock issuable upon exercise of the Warrants and a current prospectus relating to them is available (or the Company permits holders to exercise their Warrants on a cashless basis and such cashless exercise is exempt from registration under the Securities Act). The Company will agree that as soon as practicable, but in no event later than 15 business days, after the closing of the Initial Business Combination, the Company will use its best efforts to file with the SEC a registration statement for the registration, under the Securities Act, of the shares of Class A common stock issuable upon exercise of the Warrants, to cause such registration statement to become effective within 60 business days after the closing of the Initial Business Combination and to maintain a current prospectus relating to those shares of Class A common stock until the warrants expire or are redeemed, as specified in the warrant agreement. If the shares issuable upon exercise of the warrants are not registered under the Securities Act by the 60th business day after the closing of the Initial Business Combination, the Company will be required to permit holders to exercise their warrants on a “cashless basis” in accordance with Section 3(a)(9) of the Securities Act or another exemption. Notwithstanding the above, if the Company’s Class A common stock is at the time of any exercise of a warrant not listed on a national securities exchange such that it satisfies the definition of a “covered security” under Section 18(b)(1) of the Securities Act, the Company may, at its option, require holders of Warrants who exercise their warrants to do so on a “cashless basis” in accordance with Section 3(a)(9) of the Securities Act and, in the event the Company elects, the Company will not be required to file or maintain in effect a registration statement, but the Company will use its best efforts to register or qualify the shares under applicable blue sky laws to the extent an exemption is not available. The Warrants will expire five years after the completion of a Business Combination or earlier upon redemption or liquidation. The Private Placement Warrants are identical to the Warrants underlying the Units sold in the Proposed Offering, except that the Private Placement Warrants and the shares of Class A common stock issuable upon exercise of the Private Placement Warrants will not be transferable, assignable or salable until 30 days after the completion of the Initial Business Combination, subject to certain limited exceptions. Additionally, the Private Placement Warrants will be non-redeemable so long as they are held by the initial purchasers or such purchasers’ permitted transferees. If the Private Placement Warrants are held by someone other than the initial shareholders or their permitted transferees, the Private Placement Warrants will be redeemable by the Company and exercisable by such holders on the same basis as the Warrants. The Company may call the Warrants for redemption (except with respect to the Private Placement Warrants): • in whole and not in part; • at a price of $0.01 per warrant; • upon a minimum of 30 days’ prior written notice of redemption (the “30-day redemption period”); and • if, and only if, the last sale price of the Class A common stock equals or exceeds $18.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date on which the Company sends the notice of redemption to the warrantholders. If the Company calls the Warrants for redemption, management will have the option to require all holders that wish to exercise the Warrants to do so on a “cashless basis,” as described in the warrant agreement. The exercise price and number of shares of Class A common stock issuable upon exercise of the warrants may be adjusted in certain circumstances including in the event of a share dividend, or recapitalization, reorganization, merger or consolidation. In addition, if (x) the Company issues additional shares of Class A common stock or securities convertible into or exercisable or exchangeable for shares of Class A common stock for capital raising purposes in connection with the closing of the Initial Business Combination (excluding any issuance of securities under the Forward Purchase Agreement), at an issue price or effective issue price of less than $9.20 per share of Class A common stock (with such issue price or effective issue price to be determined in good faith by the Company’s board of directors and, in the case of any such issuance to the Sponsor or its affiliates, without taking into account any Founder Shares held by the Sponsor or such affiliates, as applicable, prior to such issuance (the “Newly Issued Price”)), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for funding the Initial Business Combination, and (z) the volume weighted average trading price of the Class A common stock during the 20 trading day period starting on the trading day prior to the day on which the Company consummates the Initial Business Combination (the “Market Value”) is below $9.20 per share, the exercise price of the warrants will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger price described above will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price. Additionally, in no event will the Company be required to net cash settle any warrant. In the event that a registration statement is not effective for the exercised warrants, the purchaser of a unit containing such warrant will have paid the full purchase price for the unit solely for the share of Class A common stock underlying such unit. There will be no redemption rights or liquidating distributions with respect to the warrants, which will expire worthless if the Company fails to complete an Initial Business Combination within the 18-month time period.	NOTE 4 — STOCKHOLDERS’ EQUITY Common Stock The authorized common stock of the Company includes up to 100,000,000 shares of Class A common stock and 25,000,000 shares of Class B common stock. If the Company enters into a Business Combination, it may (depending on the terms of such a Business Combination) be required to increase the number of shares of Class A common stock which the Company is authorized to issue at the same time as the Company’s stockholders vote on the Business Combination, to the extent the Company seeks stockholder approval in connection with the Business Combination. Holders of the Company’s common stock are entitled to one vote for each share of common stock. On February 3, 2020, the Company conducted a 1:575 stock split and reclassification resulting in 5,750,000 shares of Class B common stock outstanding (up to 750,000 shares of which are subject to forfeiture depending on the extent to which the underwriters’ over-allotment option is exercised). On April 21, 2020, 80,000 founder shares were transferred to the Company’s independent directors, at their par value. On May 19, 2020, 718,750 shares of Class B common stock were returned to the Company by the Sponsor for cancellation, resulting in a total of 5,031,250 Class B common stock outstanding. At September 30, 2020, there were 18,150,000 shares (which includes 16,878,805 shares subject to possible redemption) of Class A common stock issued and outstanding. Preferred Stock The Company is authorized to issue 1,000,000 shares of preferred stock with such designations, voting and other rights and preferences as may be determined from time to time by the Company’s board of directors. At September 30, 2020 and December 31, 2019, there were no shares of preferred stock issued or outstanding. Warrants Warrants may only be exercised for a whole number of shares. No fractional Warrants will be issued upon separation of the Units and only whole Warrants will trade. The Warrants will become exercisable on the later of (a) 30 days after the completion of the Business Combination or (b) 12 months from the closing of the Public Offering; provided in each case that the Company has an effective registration statement under the Securities Act covering the shares of Class A common stock issuable upon exercise of the Warrants and a current prospectus relating to them is available (or the Company permits holders to exercise their Warrants on a cashless basis and such cashless exercise is exempt from registration under the Securities Act). The Company will as soon as practicable, but in no event later than 15 business days, after the closing of the Business Combination, use its best efforts to file with the Securities and Exchange Commission (“SEC”) a registration statement for the registration, under the Securities Act, of the shares of Class A common stock issuable upon exercise of the Warrants, to cause such registration statement to become effective within 60 business days after the closing of the Business Combination and to maintain a current prospectus relating to those shares of Class A common stock until the Warrants expire or are redeemed, as specified in the Company’s warrant agreement. If the shares issuable upon exercise of the Warrants are not registered under the Securities Act by the 60th business day after the closing of the Business Combination, the Company will be required to permit holders to exercise their Warrants on a “cashless basis” in accordance with Section 3(a)(9) of the Securities Act or another exemption. Notwithstanding the above, if the Company’s Class A common stock is at the time of any exercise of a Warrant not listed on a national securities exchange such that it satisfies the definition of a “covered security” under Section 18(b)(1) of the Securities Act, the Company may, at its option, require holders of Warrants who exercise their Warrants to do so on a “cashless basis” in accordance with Section 3(a)(9) of the Securities Act and, in the event the Company elects, the Company will not be required to file or maintain in effect a registration statement, but the Company will use its best efforts to register or qualify the shares under applicable blue sky laws to the extent an exemption is not available. The Warrants will expire at 5:00 p.m., New York City time, five years after the completion of a Business Combination or earlier upon redemption or liquidation. The Private Placement Warrants are identical to the Warrants underlying the Units sold in the Public Offering, except that the Private Placement Warrants and the shares of Class A common stock issuable upon exercise of the Private Placement Warrants will not be transferable, assignable or salable until 30 days after the completion of the Business Combination, subject to certain limited exceptions. Additionally, the Private Placement Warrants will be non-redeemable so long as they are held by the Sponsor or its permitted transferees. If the Private Placement Warrants are held by someone other than the Sponsor or its permitted transferees, the Private Placement Warrants will be redeemable by the Company and exercisable by such holders on the same basis as the Warrants. The Company may call the Warrants for redemption (except with respect to the Private Placement Warrants): • in whole and not in part; • at a price of $0.01 per warrant; • upon a minimum of 30 days’ prior written notice of redemption (the “30-day redemption period”); and • if, and only if, the last sale price of the Class A common stock equals or exceeds $18.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within a consecutive 30-trading day period ending on the third trading day prior to the date on which the Company sends the notice of redemption to the warrant holders. If the Company calls the Warrants for redemption, management will have the option to require all holders that wish to exercise the Warrants to do so on a “cashless basis,” as described in the warrant agreement. The exercise price and number of shares of Class A common stock issuable upon exercise of the Warrants may be adjusted in certain circumstances including in the event of a share dividend, or recapitalization, reorganization, merger or consolidation. In addition, if (x) the Company issues additional shares of Class A common stock or securities convertible into or exercisable or exchangeable for shares of Class A common stock for capital raising purposes in connection with the closing of the Business Combination (excluding any issuance of securities under the forward purchase agreement), at an issue price or effective issue price of less than $9.20 per share of Class A common stock (with such issue price or effective issue price to be determined in good faith by the Company’s board of directors and, in the case of any such issuance to the Sponsor or its affiliates, without taking into account any Founder Shares held by the Sponsor or such affiliates, as applicable, prior to such issuance (the “Newly Issued Price”)), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for funding the Initial Business Combination, and (z) the volume weighted average trading price of the Class A common stock during the 20 trading day period starting on the trading day prior to the day on which the Company consummates the Business Combination (the “Market Value”) is below $9.20 per share, the exercise price of the Warrants will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger price described above will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price. Additionally, in no event will the Company be required to net cash settle any Warrant. In the event that a registration statement is not effective for the exercised Warrants, the purchaser of a Unit containing such Warrant will have paid the full purchase price for the Unit solely for the share of Class A common stock underlying such Unit. There will be no redemption rights or liquidating distributions with respect to the Warrants, which will expire worthless if the Company fails to complete a Business Combination within the 18-month time period.

Fair Value Instruments	9 Months Ended
Fair Value Instruments	Sep. 30, 2020
Fair Value Instruments [Abstract]
FAIR VALUE INSTRUMENTS	NOTE 5 — FAIR VALUE INSTRUMENTS The Company follows the guidance in ASC 820 for its financial assets and liabilities that are re-measured and reported at fair value at each reporting period, and non-financial assets and liabilities that are re-measured and reported at fair value at least annually. The fair value of the Company’s financial assets and liabilities reflects management’s estimate of amounts that the Company would have received in connection with the sale of the assets or paid in connection with the transfer of the liabilities in an orderly transaction between market participants at the measurement date. In connection with measuring the fair value of its assets and liabilities, the Company seeks to maximize the use of observable inputs (market data obtained from independent sources) and to minimize the use of unobservable inputs (internal assumptions about how market participants would price assets and liabilities). The following fair value hierarchy is used to classify assets and liabilities based on the observable inputs and unobservable inputs used in order to value the assets and liabilities: Level 1: Quoted prices in active markets for identical assets or liabilities. An active market for an asset or liability is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2: Observable inputs other than Level 1 inputs. Examples of Level 2 inputs include quoted prices in active markets for similar assets or liabilities and quoted prices for identical assets or liabilities in markets that are not active. Level 3: Unobservable inputs based on our assessment of the assumptions that market participants would use in pricing the asset or liability. There were no assets measure on a recurring basis at fair value at December 31, 2019. At September 30, 2020, there were cash equivalents in the amount our $176,777,682 with a fair value hierarchy of Level 1 that was used as valuation inputs by the Company to determine such fair value.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Investment in Unconsolidated Joint Venture	9 Months Ended	12 Months Ended
Investment in Unconsolidated Joint Venture	Sep. 30, 2020	Dec. 31, 2019
EOS ENERGY STORAGE, LLC [Member]
Investment in unconsolidated joint venture	6. Investment in unconsolidated joint venture In August 2019 (and as amended in August 2020), the Company entered into an agreement with Holtec Power, Inc ("Holtec") to form the unconsolidated joint venture, HI-POWER LLC ("Hi-Power" or "JV"). The JV was formed in order to manufacture the products for all of the Company's projects in North America. Accordingly, the Company will purchase battery storage systems and spare parts from the JV. The joint venture is in Turtle Creek, Pennsylvania. The Company's initial estimated financial commitment is $4,100 in the form of a combination of cash and special purpose manufacturing equipment. Eos's initial ownership interest is 49%. During the nine months ended September 30, 2020, the Company contributed $1,561 which was primarily comprised of inventory purchased by the Company on behalf of the JV. The JV is not planned to commence manufacturing activities until the fourth quarter of 2020, as a result earnings are not material. Once manufacturing activities commence, both Eos and Holtec intend to sell the products manufactured by Hi-Power. Eos will earn five percent of the product price for any products made by Hi-Power and sold by Holtec or any of its affiliates.	6. Investment in unconsolidated joint venture In August 2019, the Company entered into an agreement with Holtec Power, Inc (“Holtec”) to form the unconsolidated joint venture, HI-POWER LLC (“Hi-Power” or “JV”). The JV was formed in order to manufacture the products for all of the Company’s projects in North America. Accordingly, the Company will purchase battery storage systems and spare parts from the JV. The joint venture is in Turtle Creek, Pennsylvania. The Company’s initial estimated financial commitment is $4,100 in the form of a combination of cash and special purpose manufacturing equipment. Eos’s initial ownership interest is 49%. The joint venture is not planned to commence manufacturing activities until the third quarter of 2020, as a result earnings are not material. Once manufacturing activities commence, both Eos and Holtec intend to sell the products manufactured by Hi-Power. Eos will earn five percent of the product price for any products manufactured by Hi-Power and sold by Holtec or its affiliates.

Merger Agreement	9 Months Ended
Merger Agreement	Sep. 30, 2020
Merger Agreement
MERGER AGREEMENT	NOTE 6 — MERGER AGREEMENT On September 7, 2020, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with BMRG Merger Sub, LLC, a wholly-owned subsidiary of the Company and a Delaware limited liability company (“Merger Sub I”), BMRG Merger Sub II, LLC, a wholly-owned subsidiary of the Company and a Delaware limited liability company (“Merger Sub II”), Eos Energy Storage LLC, a Delaware limited liability company (“Eos”), New Eos Energy LLC, a wholly-owned subsidiary of Eos and a Delaware limited liability company (“Newco”) and AltEnergy Storage VI, LLC, a Delaware limited liability company (“AltEnergy”). In connection with the proposed business combination (the “Business Combination”): (1) Merger Sub I will merge with and into Newco (the “First Merger”), whereupon the separate existence of Merger Sub I will cease, and Newco will continue as the surviving company (such company, in its capacity as the surviving company of the First Merger, is sometimes referred to as the “First Surviving Company”) and become a wholly owned subsidiary of the Company; and (2) immediately following the First Merger and as part of the same overall transaction as the First Merger, the First Surviving Company will merge with and into Merger Sub II, whereupon the separate existence of the First Surviving Company will cease, and Merger Sub II will continue as the surviving company and a wholly owned subsidiary of the Company. Upon the closing of the business combination (the “Closing”), it is anticipated that the Company will change its name to “Eos Energy Enterprises, Inc.” Subject to certain downward adjustments, and the other terms and conditions set forth in the Merger Agreement, at Closing Eos’s securityholders (the “Sellers”), will receive aggregate consideration equal to up to $300 million of shares of the Company’s common stock (including shares issuable upon exercise of certain options to acquire such shares), or up to 30,000,000 shares (assuming exercise of certain options to acquire such shares). The Merger Agreement also contemplates the issuance of an additional 2,000,000 shares of the Company’s common stock to Eos’s securityholders pending the achievement (if any) of certain earnout targets pursuant to the terms of the Merger Agreement. The Closing is subject to certain customary conditions, including, among other things, that the Company has an aggregate of at least $110 million of cash (before taking into account certain expenses) available, including from the Trust Account and from the proceeds of investments of equity financing sources. In order to help meet the condition under the Merger Agreement that there is at least $110 million of cash available upon the Closing (before taking into account certain expenses), the Company entered into an Equity Commitment Letter with B. Riley Financial, pursuant to which B. Riley Financial committed to purchase up to 4,000,000 shares of Class A common stock, at a price per share of $10.00 per share, or up to $40,000,000 in equity financing at Closing, less the number of shares of Class A common stock already issued pursuant to subscription agreements entered into with investors prior to the Closing. The Equity Commitment Letter effectively terminated the forward purchase agreement entered at the time of the Public Offering requiring the Sponsor and its affiliate to purchase, immediately prior to the Closing, an aggregate of 2,500,000 units, each comprised of one share of Class A common stock and one-half of one warrant. The Company and the Sponsor will enter into a letter agreement at the Closing, pursuant to which the Sponsor will agree to subject 1,718,000 of its shares in the Company (the “Sponsor Shares”), which formerly constituted shares of Class B common stock of the Company held by the Sponsor, to certain transfer and other restrictions, under which (a) 859,000 Sponsor Shares will be restricted from being transferred unless and until either, for a period of five years after the Closing, (i) the share price of the Company equals or exceeds $12.00 per share for any 20 trading days within any consecutive 30-trading day period or (ii) a change of control occurs for a share price of the Company equaling or exceeding $12.00 per share, and (b) the remaining 859,000 Sponsor Shares are subject to similar restrictions except that the threshold is increased from $12.00 to $16.00. If after the five-year period, there are no triggering events, the Sponsor Shares will be forfeited and canceled for no consideration. If after the five-year period, only the triggering event described in clause (a) above has occurred, the remaining 859,000 Sponsor Shares described in clause (b) will be forfeited and canceled for no consideration.

Commitments and Contingencies

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Commitments and Contingencies

7. Commitments and Contingencies

Lease Commitments

On June 24, 2016, Eos entered into a long-term non-cancelable, operating lease for 45,000 sq. ft. of space for its current headquarters facility in Edison, New Jersey. On April 26, 2017, Eos entered into a lease for an additional 18,000 sq. ft. of adjoining space. These leases expire in September 2026 with renewal options up to 2036. Further, these leases require monthly rent payments along with executory costs, which include real estate taxes, repairs, maintenance, and insurance. In addition, the terms of the leases contain cost escalations of approximately 10% annually. The Company also has certain non-cancelable capital lease agreements for office equipment.

Total rent expense was $570, for both the nine months ended September 30, 2020 and 2019, respectively, of which, $0 and $102 was recorded as Cost of goods sold; $405 and $339 as Research and development expenses; and $165 and $129 as General and administrative expenses in the Statement of Operations, respectively.

Future minimum lease commitments as of September 30, 2020 are as follows:

	Operating		Capital
Remainder of 2020	$	167	$	4
2021		685		15
2022		755		6
2023		825		—
2024		895		—
Later years		1,644		—
Total minimum lease payments	$	4,971	$	25
Less amounts representing interest				3
Present value of minimum lease payments			$	22

Firm Purchase Commitments — Related Party

In July 2020, the Company entered into an $8,000 non-cancellable purchase contract with its unconsolidated joint venture partner, Hi-Power LLC, to supply batteries for existing and future sales orders. As of September 30, 2020, the Company has made deposits totaling $3,143 (Vendor Deposits – related party) which will be applied against amounts payable for future purchases under this purchase contract.

At the end of each reporting period, the Company evaluates its non-cancellable firm purchase commitments and records a loss, if any, using the same lower of cost or market approach based on the inventory guidance of ASC 330-10-35-17. In assessing the potential loss provision, we use the stated contract price and expected production volume under the relevant sales contract. The Company records a purchase commitment loss if the market selling price of Gen 2.3 Battery Systems sold to customers is less than the cost to manufacture the product.

During the nine months ended September 30, 2020 and 2019, respectively, the Company recorded a loss on firm purchase commitments of $5,807 and $0, respectively, which has been included in cost of goods sold in the statement of operations.

7. Commitments and Contingencies

Lease Commitments

On June 24, 2016, Eos entered into a long-term non-cancelable operating lease for 45,000 sq. ft. of space for its current headquarters facility in Edison, New Jersey. On April 26, 2017, Eos entered into a lease for an additional 18,000 sq. ft. of adjoining space. These leases expire in September 2026 with renewal options up to 2036. Further, these leases require monthly rent payments along with executory costs, which include real estate taxes, repairs, maintenance, and insurance. In addition, the terms of the leases contain cost escalations of approximately 10% annually. The Company also has certain non-cancelable capital lease agreements for office equipment.

Total rent expense was $930 and $1,007, for the years ended December 31, 2019 and 2018, respectively, of which, $102 and $528 was recorded as Cost of goods sold; $430 and $0 as Research and development expenses; and $398 and $479 as General and administrative expenses in the Statement of Operations, respectively.

Future minimum lease commitments as of December 31, 2019 are as follows:

	Operating		Capital
2020	$	614	$	13
2021		685		13
2022		755		4
2023		825		—
2024		895		—
Later years		1,644		—
Total minimum lease payments	$	5,418	$	30
Less amounts representing interest				5
Present value of minimum lease payments			$	25

Grant Expense, Net	9 Months Ended	12 Months Ended
Grant Expense, Net	Sep. 30, 2020	Dec. 31, 2019
EOS ENERGY STORAGE, LLC [Member]
Grant Expense, Net	8. Grant Expense, Net Eos was approved for two grants by the California Energy Commission (CEC) totaling approximately $7,000. In accordance with the grant agreements, Eos is responsible for conducting studies to demonstrate the benefits of certain energy-saving technologies to utility companies and consumers in the State of California, and is entitled to receive portions of the grants based upon expenses incurred. During the nine months ended September 30, 2020 and 2019, Eos recorded grant expense, net of $728 and ($526), respectively, which comprised of grant income of $381 and $590 and grant costs of $1,109 and $64. As of September 30, 2020, and 2019, Eos has received payments totaling $4,743 and $3,185, and has a receivable in the amount of $286 and $326 as of September 30, 2020 and December 31, 2019, respectively. The expenses incurred by Eos relate to the performance of the studies in accordance with the respective grant agreements, and the grants received or receivable from the CEC are recorded as an offset to the related expenses for which the grant is intended to compensate the Company.	8. Grant Expense, Net Eos was approved for two grants by the California Energy Commission (CEC) totaling approximately $7,000. In accordance with the grant agreements, Eos is responsible for conducting studies to demonstrate the benefits of certain energy-saving technologies to utility companies and consumers in the State of California, and is entitled to receive portions of the grants based upon expenses incurred. During the years ended December 31, 2019 and 2018, Eos recorded grant expense (income), net of $(469) and $1,418, respectively, which comprised of grant income of $984 and $1,821 and grant costs of $515 and $3,239. As of December 31, 2019 and 2018, Eos has received payments totaling $3,209 and $2,244, and has a receivable in the amount of $326 and $678 as of December 31, 2019 and 2018, respectively. The expenses incurred by Eos relate to the performance of the studies in accordance with the respective grant agreements, and the grants received or receivable from the CEC are recorded as an offset to the related expenses for which the grant is intended to compensate the Company.

Modification to the Terms of the Offering	2 Months Ended
Modification to the Terms of the Offering	Feb. 14, 2020
Modification to the Terms of the Offering [Abstract]
MODIFICATION TO THE TERMS OF THE OFFERING	NOTE 7 — MODIFICATION TO THE TERMS OF THE OFFERING On May 19, 2020, the size of the transaction was modified to 17,500,000 Units at an offering price of $10.00 per Unit. As a result, on May 19, 2020 the Sponsor returned 718,750 shares of Class B common stock to Company for cancellation. As a result of the modified terms and execution of the underwriting agreement on May 19, 2020 the financial statements have been modified to reflect the final terms of the agreement, see Note 1, Note 3, and Note 4.

Income Taxes

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Income Taxes

9. Income Taxes

For the nine month periods ending September 30, 2020 and 2019, the reported income tax provision (i.e. nil for both periods) differs from the amount computed by applying the statutory US federal income tax rates of 21% to the income before income taxes due to pretax losses for which no tax benefit can be recognized and nondeductible interest expense for US income tax purposes.

The Company estimates and applies the annual effective tax rate to its ordinary earnings each interim period. Any significant unusual or infrequent items, if any, are not included in the estimation of the annual effective tax rate. Rather, these items and their related income tax expense (benefit) are separately stated in the interim period in which they occur. The quarterly estimate of the annual effective tax rate and related tax expense is subject to variation due to a multitude of factors. Factors may include, but are not limited to the inability to accurately predict the Company’s pre-tax and taxable income and loss.

At each balance sheet date, management assesses the likelihood that Eos will be able to realize its deferred tax assets. Management considered all available positive and negative evidence in assessing the need for a valuation allowance. The realization of deferred tax assets depends on the generation of sufficient taxable income of the appropriate character and in the appropriate taxing jurisdiction during the future periods in which the related temporary differences become deductible. Management has determined that it is unlikely that Eos will be able to utilize its deferred tax assets at September 30, 2020 and December 31, 2019 due to cumulative losses. Therefore, Eos has a valuation allowance against its net deferred tax assets.

At September 30, 2020 and December 31, 2019, Eos has not recorded any unrecognized tax benefits associated with uncertain tax positions.

Eos files income tax returns in federal and various state jurisdictions. The open tax years for federal and state returns are generally 2016 and forward. In addition, net operating losses generated in closed years and utilized in open years are subject to adjustment by the tax authorities. Eos is not currently under examination by any taxing jurisdiction.

On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was signed into law in response to the Covid-19 pandemic. The CARES Act provided several forms of tax law changes, though Eos does not expect that any will have a material impact on the tax provision.

9. Income Taxes

Eos is subject to regulation under U.S. federal and U.S. state tax laws, regulations and policies. Changes to these laws or regulations may affect the Company’s tax liability, return on investments and business operations.

Earnings before income taxes

Net loss before income taxes for domestic operations for the years ended December 31, 2019 and 2018 was $(79,483) and $(28,498), respectively.

Income expense (benefit)

Income tax expense (benefit) for the years ended December 31, 2019 and 2018 was as follows:

	2019		2018
Current expense (benefit):
U.S. federal	$	—	$	—
U.S. state and local		—		—
Total current income tax (benefit) provision		—		—
Deferred expense (benefit):
U.S. federal	$	—	$	—
U.S. state and local		—		—
Total deferred income tax (benefit) provision		—		—
Total income tax (benefit) provision	$	—	$	—

Eos has no tax provision (benefit) for the periods ended December 31, 2019 and 2018 due the generation of taxable losses offset by a valuation allowance, discussed below, on the deferred tax assets.

Reconciliation of US Federal Statutory income tax rate to actual income tax rate

The reconciliation from the statutory U.S. federal income tax rate to the effective tax rate is as follows:

	2019			2018
Income (loss) before income taxes	$	(79,483	)	$	(28,498	)
Statutory U.S. federal income tax (21%)		(16,691	)		(5,985	)
State and local income tax		1,548			768
Disallowed interest expense		11,903			—
Federal R&D credit		(1,002	)		(1,065	)
Valuation allowance		4,215			6,276
Other		27			6
Total income tax expense		—			—
Effective tax rate		0	%		0	%

The reported income tax provision differs from the amount computed by applying the statutory US federal income tax rate of 21% to the income before income taxes due to pretax losses for which no tax benefit has been provided and nondeductible interest expense for US income tax purposes.

Deferred Income Taxes

Eos records deferred income taxes to reflect the net tax effects of temporary differences, if any, between the carrying amounts of assets and liabilities for financial reporting and the amounts used for income tax purposes. The components of deferred tax assets and liabilities at December 31, 2019 and 2018 were as follows:

	2019			2018
Deferred tax assets:
NOL carryforwards	$	30,540		$	26,858
Tax credit carryforwards		4,346			4,390
Employee compensation		187			211
Accruals and reserves		543			136
Organizational costs		194			24
Deferred tax assets, gross	$	35,810			31,619
Valuation allowance	$	(34,773	)		(30,558	)
Total deferred tax assets, net	$	1,037		$	1,061
Deferred tax liabilities:
Fixed assets		(1,010	)		(1,061	)
Investment in partnership		(27	)		—
Deferred tax liabilities		(1,037	)		(1,061	)
Total deferred tax asset (liability)	$	—		$	—

Eos’s net deferred tax balances consists primarily of federal and state net operating losses (“NOLs”) available for carry forward, research and development credits, and differences in the basis of property and equipment for the years ended December 31, 2019 and 2018.

During 2018, the Company participated in a tax certificate transfer program with the state of New Jersey and sold a portion of its available prior year New Jersey state NOLs, in varying amounts from tax years 2016 and 2017. During 2019, the Company participated in this same program with the state of New Jersey and sold a portion of its available prior year New Jersey state NOLs and R&D credits, in varying amounts from tax years 2016, 2017 and 2018. The deferred tax balances and related disclosures below reflect the adjusted attribute carryforwards and associated deferred tax assets post-sale of the prior years’ attributes.

The Company maintains a valuation allowance where it is more-likely-than-not that all or a portion of a deferred tax asset may not be realized. Changes in the valuation allowances are included in the Company’s income tax provision in the period of change. In determining whether a valuation allowance is required, the Company evaluates factors such as prior earnings history, expected future earnings, reversal of existing taxable temporary differences, carry back and carry forward periods and tax planning strategies that could potentially enhance the likelihood of the realization of a deferred tax asset. Management has determined that it is more-likely-than not that Eos will not be able to utilize its deferred tax assets at December 31, 2019 and 2018 due to cumulative losses. As such, Eos has a valuation allowance against its net deferred tax assets.

Valuation allowance increased by $4,215 between December 31, 2019 and 2018. The increase/decrease was primarily attributable to an increase in NOL and tax credit carryforwards.

Net Operating Losses & Tax Credits

As of December 31, 2019 and 2018, Eos has federal research and development tax credits (“R&D credit”) of approximately $3,733 and $2,731, which begin to expire in varying amounts from 2032 – 2039 and 2032 – 2038, respectively. In addition, Eos has state R&D credits of approximately $613 and $1,657, which will expire in varying amounts from 2025 – 2026 and 2023 – 2025 for the years ended December 31, 2019 and 2018, respectively.

The Company has NOL carryforwards for tax purposes and other deferred tax assets that are available to offset future taxable income.

As of December 31, 2019 and 2018, Eos has gross federal NOL carryforwards of approximately $137,612 and $117,018. As of December 31, 2019, Eos has state NOL carryforwards of $24,008. As of December 31, 2018 Eos has NOLs generated in 2018 of $27,378 and NOLs generated in prior years of $7,552, for total state NOLs of $34,930. Regarding the federal NOL for the year ended December 31, 2019, $89,051 begins to expire in varying amounts from 2033 through 2037, while $48,561 has an indefinite carryforward period. The state NOL carryforwards begin to expire in varying amounts from 2036 through 2039. The US (federal and state) operating loss carry forwards and credits may be subject to an annual limitation due to the “change in ownership” provisions of the Internal Revenue Code, and similar state provisions. The Company is still assessing whether these provisions apply.

Unrecognized Tax Benefits

The Company is subject to income taxes in the United States (federal and state). Significant judgment is required in evaluating the Company’s tax positions and determining Eos’s provision for income taxes. During the ordinary course of business, there are transactions and calculations for which the ultimate tax determination is uncertain. The Company establishes reserves for tax-related uncertainties based on estimates of whether, and the extent to which, additional taxes will be due. These reserves are established when we believe that certain positions might be challenged.

Eos has not recorded any unrecognized tax benefits associated with uncertain tax positions as of December 31, 2019 and 2018.

The open tax years for federal and state tax returns is generally 2016 and forward. Net operating losses and R&D credits generated in closed years and utilized in open years are subject to adjustment by the tax authorities. Eos is not currently under examination by any taxing jurisdiction.

The Company regularly assesses the adequacy of its provision for income tax contingencies in accordance with ASC 740. As a result, the Company may adjust the reserves for unrecognized tax benefits for the impact of new facts and developments, such as changes to interpretation of relevant tax law, assessments from taxing authorities, settlements with tax authorities and lapses of statute of limitations.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Related Party Transactions	2 Months Ended	9 Months Ended	12 Months Ended
Related Party Transactions	Feb. 14, 2020	Sep. 30, 2020	Dec. 31, 2019
RELATED PARTY TRANSACTIONS	NOTE 4 — RELATED PARTY TRANSACTIONS Founder Shares On June 3, 2019, 10,000 shares of our common stock were issued to B. Riley Principal Investments, LLC. On February 3, 2020, the Company conducted a 1:575 stock split, resulting in B. Riley Principal Investments, LLC holding 5,750,000 shares of Class B common stock (the “Founder Shares”). All of the Founder Shares were contributed to the Sponsor in January 2020. The financial statements reflect the issuance of these shares retroactively for all periods presented. On May 19, 2020, the Sponsor returned 718,750 shares of Class B common stock to Company for cancellation, resulting in a total of 5,031,250 Founder Shares outstanding. As used herein, unless the context otherwise requires, Founder Shares shall be deemed to include the shares of Class A common stock issuable upon conversion thereof. The Founder Shares are identical to the Class A common stock included in the Units being sold in the Proposed Offering, the Founder Shares automatically convert into shares of Class A common stock at the time of the Initial Business Combination and are subject to certain transfer restrictions, as described in more detail below, and the holders of the Founder Shares, as described in more detail below, have agreed to certain restrictions and will have certain registration rights with respect thereto. Up to 656,250 Founder Shares are subject to forfeiture depending on the extent to which the underwriters’ over-allotment option is exercised. The number of Founder Shares issued was determined based on the expectation that the Founder Shares would represent 20% of the outstanding shares of common stock upon completion of the Proposed Offering excluding the shares underlying the Private Placement Units. If the Company increases or decreases the size of the Proposed Offering, the Company will effect a stock dividend or share contribution back to capital, as applicable, with respect to its Class B Common Stock immediately prior to the consummation of the Proposed Offering in such amount as to maintain the Founder Share ownership of the Company’s stockholders prior to the Proposed Offering at 20.0% of the Company’s issued and outstanding common stock upon the consummation of the Proposed Offering. The Company’s initial stockholders, officers and directors have agreed, not to transfer, assign or sell any Founder Shares held by them until the earlier to occur of: (i) one year after the completion of the Initial Business Combination, (ii) the last sale price of Class A common stock equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within any consecutive 30-trading day period commencing at least 150 days after the Initial Business Combination, or (iii) the date following the completion of the Initial Business Combination on which the Company completes a liquidation, merger, stock exchange, reorganization or other similar transaction that results in all of the public stockholders having the right to exchange their shares of common stock for cash, securities or other property. Administrative Fees Commencing on the date of the prospectus, the Company will agree to pay an affiliate of our sponsor a total of $10,000 a month for office space, utilities and secretarial and administrative support. Upon completion of our Initial Business Combination or our liquidation, we will cease paying these monthly fees. Registration Rights The holders of Founder Shares, Private Placement Units, Private Placement Shares, Private Placement Warrants and units that may be issued upon conversion of working capital loans, if any, will have registration rights to require the Company to register the resale of any of its securities held by them (in the case of the Founder Shares, only after conversion of such shares to shares of Class A common stock) pursuant to a registration rights agreement to be signed on or before the effective date of the Proposed Offering. These holders will also be entitled to certain piggyback registration rights. However, the registration rights agreement provides that the Company will not permit any registration statement filed under the Securities Act to become effective until termination of the applicable lock-up period for the securities to be registered. The Company will bear the expenses incurred in connection with the filing of any such registration statements. The holder of Forward Purchase Units has substantially similar registration rights. Note Payable — Related Party The Company borrowed $50,000 on February 4, 2020 in accordance with the note payable to Sponsor which allows the Company to borrow up to $300,000 without interest to be used for a portion of the expenses of this offering. The notes payable is payable on the earlier of: (i) December 31, 2021 or (ii) the date on which the Company consummates an initial public offering of its securities. As of February 14, 2020, the note payable due to related party was $50,000. Forward Purchase Agreement The Company will agree to enter into a Forward Purchase Agreement with an affiliate of the Sponsor, pursuant to which the affiliate of the Sponsor will agree to purchase, or have its designees purchase, an aggregate of 2,500,000 units, at a price of $10.00 per unit, or $25,000,000 in the aggregate, in a private placement to close concurrently with the initial business combination. The obligations under the Forward Purchase Agreement do not depend on whether any public stockholders redeem their Class A common stock and provide the Company with a minimum funding level for the Initial Business Combination. The Forward Purchase Agreement includes registration rights with respect to the Forward Purchase Units.	NOTE 3 — RELATED PARTY TRANSACTIONS Founder Shares On June 3, 2019, 10,000 shares of the Company’s common stock were issued to B. Riley Principal Investments, LLC. On February 3, 2020, the Company conducted a 1:575 stock split and reclassification, resulting in B. Riley Principal Investments, LLC holding 5,750,000 shares of Class B common stock, representing the “Founder Shares”. All of the Founder Shares were contributed to the Sponsor in January 2020. The financial statements reflect the issuance of these shares retroactively for all periods presented. On April 21, 2020, 20,000 Founder Shares were transferred to each of four independent directors of the Company, at their par value. On May 19, 2020, the Sponsor returned 718,750 shares of Class B common stock to Company for cancellation, resulting in a total of 5,031,250 Founder Shares outstanding. As used herein, unless the context otherwise requires, Founder Shares shall be deemed to include the shares of Class A common stock issuable upon conversion thereof. The Founder Shares are identical to the Class A common stock included in the Units sold in the Public Offering, the Founder Shares will automatically convert into shares of Class A common stock at the time of the Business Combination and are subject to certain transfer restrictions, as described in more detail below, and the holders of the Founder Shares, as described in more detail above, have agreed to certain restrictions and will have certain registration rights with respect thereto. Up to 656,250 Founder Shares were subject to forfeiture depending on the extent to which the underwriters’ over-allotment option to purchase additional Units was exercised. On May 28, 2020, the underwriters confirmed that they will not be exercising their over-allotment option in whole or in part, as such 656,250 Founder Shares have been forfeited. The number of Founder Shares issued was determined based on the expectation that the Founder Shares would represent 20% of the outstanding shares of Company common stock upon completion of the Public Offering excluding the shares underlying the Private Placement Units (the “Private Placement Shares”). The Company’s initial stockholders, officers and directors have agreed, subject to limited exceptions, not to transfer, assign or sell any Founder Shares held by them until the earlier to occur of: (i) one year after the completion of the Business Combination, (ii) the last sale price of Class A common stock equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within any consecutive 30-trading day period commencing at least 150 days after the Business Combination, or (iii) the date following the completion of the Business Combination on which the Company completes a liquidation, merger, stock exchange, reorganization or other similar transaction that results in all of the public stockholders having the right to exchange their shares of common stock for cash, securities or other property. Business Combination Marketing Agreement Pursuant to a business combination marketing agreement, the Company engaged B. Riley Securities, Inc., at that time known as B. Riley FBR, Inc., as advisors in connection with its Business Combination to assist it in arranging meetings with its stockholders to discuss a potential business combination and the target business’ attributes, introduce it to potential investors that may be interested in purchasing its securities, assist it in obtaining stockholder approval for its Business Combination and assist it with the preparation of press releases and public filings in connection with the Business Combination. The Company will pay B. Riley Securities, Inc. for such services upon the consummation of the Business Combination a cash fee in an amount equal to 3.5% of the gross proceeds of the Public Offering (exclusive of any applicable finders’ fees which might become payable). Pursuant to the terms of the business combination marketing agreement, no fee will be due if the Company does not complete a Business Combination. Administrative Fees Commencing on May 19, 2020, the Company agreed to pay an affiliate of the Sponsor a total of $10,000 per month for office space, utilities and secretarial and administrative support. During the three and nine months ended September 30, 2020, the Company was charged a total of $44,194 by the Sponsor. These amounts are included in amounts payable to related party at September 30, 2020. Upon completion of the Company’s Business Combination or liquidation, the Company will cease paying these monthly fees. Registration Rights The holders of Founder Shares (and any shares of Class A common stock issuable upon conversion of the Founder Shares), Private Placement Units, Private Placement Shares, Private Placement Warrants (and any shares of Class A common stock issuable upon the exercise of the Private Placement Warrants) and any securities that may be issued upon conversion of working capital loans, if any, have registration rights to require the Company to register the resale of any of its securities held by them (in the case of the Founder Shares, only after conversion of such shares to shares of Class A common stock) pursuant to a registration rights agreement. The holders of the majority of these securities are entitled to make up to three demands, excluding short form demands, that the Company register such securities. These holders are also entitled to certain piggyback registration rights with respect to registration statements filed subsequent to the completion of the Business Combination and rights to require the Company to register for resale such securities pursuant to Rule 415 under the Securities Act. However, the registration rights agreement provides that the Company will not permit any registration statement filed under the Securities Act to become effective until termination of the applicable lock-up period for the securities to be registered. The Company will bear the expenses incurred in connection with the filing of any such registration statements. Notwithstanding the foregoing, the Sponsor may not exercise its demand and piggyback registration rights after five and seven years, respectively, after the effective date of the registration statement of which this prospectus forms a part and may not exercise its demand rights on more than one occasion. Note Payable — Related Party The Company had a Note Payable to the Sponsor which allowed the Company to borrow up to $300,000 without interest to be used for a portion of the expenses associated with the Public Offering. The Note Payable was payable on the earlier of: (i) December 31, 2019 or (ii) the date on which the Company consummated an initial public offering of its securities. In February 2020, the Company borrowed $50,000 and in April 2020 the Company borrowed an additional $50,000 which increased the Note Payable balance to $100,000 which was paid in full using proceeds from the Public Offering and the Private Placement. At September 30, 2020, there were no amounts outstanding on the Note Payable. Equity Commitment Letter As further described in Note 6 below, in connection with the proposed Business Combination with Eos, on September 7, 2020, the Company entered into an equity commitment letter with B. Riley Financial (the “Equity Commitment Letter”), pursuant to which B. Riley Financial committed to purchase up to 4,000,000 shares of Class A common stock, at a price per share of $10.00 per share, or up to $40,000,000 in equity financing at Closing, less the number of shares of Class A common stock issued pursuant to subscription agreements with investors entered into prior to the Closing. The Equity Commitment Letter effectively terminated the forward purchase agreement entered at the time of the Public Offering requiring the Sponsor and its affiliate to purchase immediately prior to the closing of the Business Combination an aggregate of 2,500,000 units, each comprised of one share of Class A common stock and one-half of one warrant.
EOS ENERGY STORAGE, LLC [Member]
RELATED PARTY TRANSACTIONS		10. Related Party Transactions Convertible Notes Payable During the nine months ended September 30, 2020 and 2019, Eos issued convertible notes payable to certain members. Refer to Note 11 for further discussion. Commitment and Related Party Transaction During the nine months ended September 30, 2020 and 2019, Eos incurred monthly management fees to an entity owned by a board member in relation to the use of a New York City office. Total costs incurred during the respective nine months ended amounted to $0 and $19, respectively, which are included in General and administrative expense in the Statements of Operations. Unpaid management fees of $73 are included in Accounts payable and accrued expenses as of September 30, 2020 and December 31, 2019. Loan to Affiliate In prior years, Eos provided temporary advances to affiliated companies based upon certain expenses that were paid by Eos on behalf of the affiliates. The unpaid balance of advances to affiliates as of September 30, 2020 and December 31, 2019 was $23, and is included in Prepaid and other current assets on the Balance Sheet. Accounts Payable and Accrued Expenses Accounts payable and accrued expenses as of September 30, 2020 includes $145 due to Hi-Power for testing services during the nine months ended September 30, 2020.	10. Related Party Transactions Convertible Notes Payable During the years ended December 31, 2019 and 2018, Eos issued convertible notes payable to certain members. Refer to Note 11 for further discussion. Commitment and Related Party Transaction During the years ended December 31, 2019 and 2018, Eos incurred monthly management fees to an entity owned by a board member in relation to the use of a New York City office. Total costs incurred during the year amounted to $19 and $274, respectively, which are included in General and administrative expense in the Statements of Operations. Unpaid management fees of $73 and $54 are included in Accounts payable and accrued expenses as of December 31, 2019 and 2018, respectively. Loan to Affiliate In prior years, Eos provided temporary advances to affiliated companies based upon certain expenses that were paid by Eos on behalf of the affiliates. The unpaid balance of advances to affiliates as of December 31, 2019 and 2018 was $23, and is included in Prepaid and other current assets on the Balance Sheet.

Convertible Notes Payable

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Convertible Notes Payable

11. Convertible Notes Payable

Convertible Notes Payable — Related Party

During the nine months ended September 30, 2020 and the year ended December 31, 2019, the Company issued Convertible notes payable — related party with aggregate principal of $5,299 and $19,524, respectively (the "Convertible Notes"). The Convertible Notes are secured by all assets and intellectual property of the Company. AltEnergy Storage Bridge, LLC ("AltEnergy") and its affiliates have combined beneficial ownership in the Company exceeding 10% and therefore constitute a related party of the Company, pursuant to ASC 850, Related Parties. As of September 30, 2020 and December 31, 2019, AltEnergy owned approximately 18% and 20% of the Company's Common and Preferred Units, respectively.

The remaining note holders do not meet the definition of a related party under ASC 850. However, the Convertible Notes were issued to each of the note holders under identical terms, and AltEnergy serves as the administrative agent of all note holders under the Convertible Note agreements. Therefore, the disclosures within Note 11 encompass all of the Convertible Notes.

Phase I Convertible Notes Payable — Related Party

Convertible Notes with aggregate principal of $13,529 were issued from February 2019 to May 2019 (the "Phase I Notes"). $4,137 of the Phase I Notes were issued to AltEnergy.

The terms of the Phase I Notes are summarized as follows:

• Maturity: On or after June 30, 2019.

• Conversion Option: At any time, the Holder may elect to convert 1.15 times the outstanding principal balance into the preferred units of the Company at $1.75 per unit.

• Liquidation Amount: Repayment shall be made at the applicable liquidation amount. The Liquidation Amount applies to all repayments, with the exception of early repayments made at the Company's option. The Liquidation Amount applicable to repayments occurring prior to June 1, 2019 is 1.5 times the outstanding principal balance. At June 1, 2019 and August 1, 2019, the multiple increases to 2.0 and 3.0 times the outstanding principal balance, respectively.

• Optional Prepayment: The Company may prepay the Phase I Notes prior to maturity at 3.0 times the outstanding principal balance.

• Conversion upon Qualified Financing: In the event that the Company issues and sells any units to investors through a Qualified Financing, on or before the date the Phase I Notes are repaid in full, resulting in aggregate gross equity proceeds of at least $25,000, the Company may at its sole option, force the Holders to convert the Liquidation Amount into the class of equity issued in the Qualified Financing. The number of units issued at conversion are variable and shall be based upon the price per unit paid in the financing. Alternatively, the Company may also elect to settle the Phase I Notes in cash.

• Holders' put options: If an Event of Default occurs, and at the direction of 25% of the holders, repayment at the applicable Liquidation Amount becomes immediately due on demand. Any time prior to September 30, 2019, if Event of Default has not occurred, and at the direction of a majority of holders, the Liquidation Amount becomes due on demand.

In conjunction with the 2019 Phase II Note issuance, the Phase I Notes maturity date was extended to October 31, 2019. The term extension was considered a troubled debt restructuring and did not result in a substantial modification. Therefore, the extension was accounted for as a continuation of the existing Phase I Notes. An extinguishment charge was not recognized.

2019 Phase II Convertible Notes Payable — Related Party

Convertible Notes with aggregate principal of $5,995 were issued from June 2019 to December 2019 ("2019 Phase II Notes"). $2,017 of the 2019 Phase II Notes were issued to AltEnergy.

The terms of the 2019 Phase II Notes are identical to the Phase I Notes, except as follows:

• Maturity: On or after October 31, 2019.

• At any time, the holder may elect to convert 1.15 times the outstanding principal balance into the Preferred Units of the Company at $0.50 per unit.

• The Liquidation Amount is 6.0 times the outstanding principal balance, regardless of the repayment date.

• Holders' put option: If an Event of Default occurs, and at the direction of 25% of the holders, repayment at the applicable Liquidation Amount becomes immediately due on demand. If Event of Default has not occurred, Holders cannot accelerate repayment.

• 2019 Phase II Notes are Senior to Phase I Notes: In the event that the Company is obligated, or elects, to repay the Convertible Notes and does not have sufficient funds to repay all Notes in full, payments shall be made in the following order: first, to the holders of 2019 Phase II Notes until each holder has received a repayment equal to 2.0 times (2.0x) the then outstanding principal balance of holder's 2019 Phase II Notes; second, to the holders of Phase I Notes until each holder has received a repayment equal to 1.0 times (1.0x) the then outstanding principal balance of those holder's Phase I Notes; and third, to all holders of the Convertible Notes, pro rata based on the remaining amount due to each holder pursuant to the terms and provisions of each Convertible Note held by that holder.

Concurrent to issuance of the 2019 Phase II Notes, the Company entered into subscription agreements to sell Preferred Units to the Holders equal to the principal balance of the 2019 Phase II Notes at a price of $0.50 per unit. 2019 Phase II cash proceeds totaled $11,991. The proceeds were allocated to the 2019 Phase II Notes and Preferred Units based on their relative fair values at the date of issuance. The Company recognized $2,031 attributable to the 2019 Phase II Preferred Units, which was recorded as a discount against the 2019 Phase II Notes. Refer to Note 14 for further discussion regarding the Preferred Units.

2020 Phase II Convertible Notes Payable — Related Party

During the nine months ended September 30, 2020, the Company issued Convertible Notes (the "2020 Phase II Notes") concurrently with Preferred Units to certain investors for aggregate cash proceeds of $10,598. The terms of the 2020 Phase II Notes are identical to the 2019 Phase II Notes.

The proceeds were allocated to the 2020 Phase II Notes and Preferred Units based on their relative fair values at the date of issuance. The Company recognized $1,759 attributable to the 2020 Phase II Preferred Units, which was recorded as a discount against the 2020 Phase II Notes. $1,075 of the of the 2020 Phase II Notes were issued to AltEnergy. Refer to Note 14 for further discussion regarding the Preferred Units.

Beneficial Conversion Features

The conversion option on the Phase I Notes generated a beneficial conversion feature (BCF). A BCF arises when a debt or equity security is issued with an embedded conversion option that is in the money at inception because the conversion option has an effective strike price that is less than the fair value of the underlying equity security at the commitment date. The Company recognized this BCF by allocating the intrinsic value of the conversion option to additional paid-in capital, which resulted in a discount on the Phase I Notes. The Company amortized the discount into interest expense on the commitment date, as the conversion option is immediately exercisable.

Embedded Derivatives

Both the occurrence of a Qualified Financing and the exercise of the holders' put options represent contingent events outside the Company's control that can accelerate repayment of the Convertible Notes. Therefore, these features constitute embedded derivatives that require bifurcation pursuant to ASC 815-15, Embedded Derivatives.

In the event of a Qualified Financing occurring prior to July 31, 2019, the Phase I Notes can be repaid at a 1.5x or 2.0x Liquidation Amount, thereby resulting in an embedded derivative at issuance. During the nine months ended September 30, 2020 and 2019, embedded derivative liabilities with initial fair value of $411 and $618 were recognized, respectively. These amounts were recorded as discounts on the Convertible Notes. As of September 30, 2020 and December 31, 2019, the embedded derivatives were classified as current liabilities on the consolidated balance sheet and had fair values of $371 and $1,681, respectively. During the nine months ended September 30, 2020 and 2019, a change in fair value of embedded derivative gain of $1,721 and a loss of $1,528 has been recognized, respectively. Amortization of the discounts and premiums are discussed below.

The Company accounted for the Convertible Notes as deeply discounted zero coupon debt instruments. The balances payable at maturity reflect liquidation multiples of 3.0, 6.0, and 6.0 times the stated face value of the Phase I Notes, 2019 Phase II Notes, 2020 Phase II Notes, respectively. The following balances were recognized upon issuance of the Convertible Notes during the nine months ended September 30, 2020 and the year ended December 31, 2019:

							September 30, 2020 Phase II			Total
	December 31, 2019
	Phase I			Phase II
Convertible notes payable	$	40,587		$	35,973		$	31,793		$	108,353
Discount, original issuance		(20,946	)		(23,982	)		(21,196	)		(66,124	)
Premium (discount), embedded derivative		181			(1,145	)		(411	)		(1,375	)
Discount, fair value of preferred units		—			(2,031	)		(1,759	)		(3,790	)
Discount, beneficial conversion features		(1,799	)		—			—			(1,799	)
Convertible notes payable, net	$	18,023		$	8,815		$	8,427		$	35,265

Subsequent Measurement

With respect to the Phase I Notes, the holders' put option is immediately exercisable at 1.5 times the Notes. Pursuant to ASC 470-10, which states that notes with demand features should be stated at or near the amount of cash that could be required to satisfy, a corresponding portion of the premium was amortized into interest expense immediately following issuance. Additionally, the discount attributable to the BCF was immediately amortized into interest expense at issuance. The remaining discount on the Phase I Notes was amortized into interest expense using the effective interest method through July 31, 2019, the date at which the note becomes payable at 3.0 times the outstanding principal amount.

Discounts on the 2019 Phase II Notes and 2020 Phase II Notes were amortized into interest expense using the effective interest method through the stated maturity date of October 31, 2019. On October 31, 2019, the Company defaulted under the 2019 Phase II Note agreements, at which time the note holders' put option became exercisable. Discounts on 2019 Phase II Notes issued subsequent to October 31, 2019 were immediately amortized into interest expense upon issuance.

At issuance, the annual effective interest rates on the Phase I Notes were in excess of 400%. The 2019 Phase II Notes and 2020 Phase II Notes were issued with annual effective interest rates in excess of 1200%. During the nine months ended September 30, 2020 and 2019, the Company recognized aggregate interest expense of $23,366 and $30,851 related to the Convertible Notes, respectively.

As of both September 30, 2020 and December 31, 2019, the total principal and accrued interest on the Phase I Notes, 2019 Phase II Notes, and 2020 Phase II Notes is equal to the applicable Liquidation Amount of 3.0, 6.0, and 6.0 times the outstanding principal, respectively. As of September 30, 2020, and December 31, 2019 the Convertible Notes are convertible to approximately 34.9 million and 22.7 million Preferred Units of the Company, respectively.

The balances attributable to the Convertible Notes on September 30, 2020 are as follows:

	Phase I			Phase II			September 30, 2020
Convertible notes payable	$	40,587		$	67,766		$	108,353
Discount, original issuance		(20,946	)		(45,178	)		(66,124	)
Premium (discount), embedded derivative		181			(1,556	)		(1,375	)
Discount, fair value of preferred units		—			(3,790	)		(3,790	)
Discount, beneficial conversion features		(1,799	)		—			(1,799	)
Discount, accumulated amortization		22,564			50,524			73,088
Convertible notes payable, net	$	40,587		$	67,766		$	108,353

The balances attributable to the Convertible Notes on December 31, 2019 are as follows:

	Phase I			Phase II			December 31, 2019
Convertible notes payable	$	40,587		$	35,972		$	76,559
Discount, original issuance		(20,946	)		(23,982	)		(44,928	)
Premium (discount), embedded derivative		181			(1,145	)		(964	)
Discount, fair value of preferred units		—			(2,031	)		(2,031	)
Discount, beneficial conversion features		(1,799	)		—			(1,799	)
Discount, accumulated amortization		22,564			27,158			49,722
Convertible notes payable, net	$	40,587		$	35,972		$	76,559

As of September 30, 2020, aggregate Phase I and Phase II Notes attributable to AltEnergy totaled $30,965.

11. Convertible Notes Payable

2018 Notes Payable

In December 2018, the Company issued $1,000 of notes payable with a maturity date of the earlier of the date of receipt of the payment of cash from the monetization of the Company’s 2016 and 2017 New Jersey net operating losses or January 15, 2019. They are unsecured and bear interest at the rate of 15% per year. The Company repaid the notes payable on January 2, 2019.

2018 Convertible Notes Payable — Related Party

During the year ended December 31, 2018, the Company issued Convertible notes payable — related party with aggregate principal totaling $2,350 to certain investors (the “2018 Convertible Notes”). The 2018 Convertible Notes are unsecured, bear interest at the greater of 3% per year or 5% of the outstanding principal balance at maturity. In the event the Company conducts an equity offering resulting in aggregate gross proceeds of at least $10,000 before the 2018 Convertible Notes are repaid in full, the Company can force holders to convert the 2018 Convertible Notes and accrued interest into Preferred Units of the Company.

The Company determined the initial carrying value of the 2018 Convertible Notes to be $2,350 at the date of issuance. The Company determined the conversion feature does not constitute an embedded derivative pursuant to ASC 815-15, Embedded Derivatives because the 2018 Convertible Notes do not allow for net settlement upon conversion and the Company’s Preferred Units are not readily convertible to cash. Debt issuance costs associated with the Notes were immaterial and expensed as incurred.

During January 2019, the Company issued an additional $2,551 of Convertible Notes to certain investors on terms similar to the 2018 Convertible Notes. Both the 2018 Convertible Notes and January 2019 Convertible Notes were modified in April 2019 in conjunction with the Phase I Note issuance. The modification was accounted for an extinguishment of the existing Convertible Notes. The modified Phase I Notes were initially recognized at their fair value of $11,012, which resulted in an extinguishment loss of $6,111.

Refer to subsequent discussion for related party considerations applicable to both the 2018 and 2019 Convertible Notes.

2019 Convertible Notes Payable — Related Party

During the year ended December 31, 2019, the Company issued Convertible notes payable — related party with aggregate principal of $19,524 (the “2019 Convertible Notes”). The 2019 Convertible Notes are secured by all assets and intellectual property of the Company. AltEnergy Storage Bridge, LLC (“AltEnergy”) and its affiliates have combined beneficial ownership in the Company exceeding 10% and therefore constitute a related party of the Company, pursuant to ASC 850, Related Parties. As of December 31, 2019, AltEnergy owned approximately 20% of the Company’s Common and Preferred Units. As of December 31, 2018 AltEnergy owned approximately 19% of the Common and Preferred Units. The remaining holders of the 2018 and 2019 Convertible Notes do not meet the definition of a related party under ASC 850. However, the disclosures within Note 11 encompass all of the 2018 and 2019 Convertible Notes. The 2019 Convertible Notes were issued under identical terms, with AltEnergy specifically serving as the administrative agent on behalf of all holders under the 2019 Convertible Notes agreements.

Phase I Notes

The 2019 Convertible Notes were issued on various dates through two phases. The first phase with aggregate principal of $13,529 was issued through May 2019 (the “Phase I Notes”), of which $4,137 was issued to AltEnergy.

The terms of the Phase I Notes are summarized as follows:

• Maturity: On or after June 30, 2019.

• Conversion Option: At any time, the Holder may elect to convert 1.15 times the outstanding principal balance into the preferred units of the Company at $1.75 per unit.

• Liquidation Amount: Repayment shall be made at the applicable liquidation amount. The Liquidation Amount applies to all repayments, with the exception of early repayments made at the Company’s option. The Liquidation Amount applicable to repayments occurring prior to June 1, 2019 is 1.5 times the outstanding principal balance. At June 1, 2019 and August 1, 2019, the multiple increases to 2.0 and 3.0 times the outstanding principal balance, respectively.

• Optional Prepayment: The Company may prepay the Phase I Notes prior to maturity at 3.0 times the outstanding principal balance.

• Holders’ put options: If an Event of Default occurs, and at the direction of 25% of the holders, repayment at the applicable Liquidation Amount becomes immediately due on demand. Any time prior to September 30, 2019, if Event of Default has not occurred, and at the direction of a majority of holders, the Liquidation Amount becomes due on demand.

In conjunction with the Phase II Note issuance, the Phase I maturity date was extended to October 31, 2019. The term extension was considered a troubled debt restructuring and did not result in a substantial modification and was accounted for as a continuation of the existing Phase I Notes. An extinguishment charge was not recognized.

Phase II Notes

The second phase with aggregate principal of $5,995 was issued through December 2019 (the “Phase II Notes”), of which $2,017 was issued to AltEnergy.

The terms of the Phase II Notes are identical to the Phase I Notes, except as follows:

• Maturity: On or after October 31, 2019.

• At any time, the holder may elect to convert 1.15 times the outstanding principal balance into the Preferred Unites of the Company at $0.50 per unit.

• The Liquidation Amount is 6.0 times the outstanding principal balance, regardless of the repayment date.

• Holders’ put option: If an Event of Default occurs, and at the direction of 25% of the holders, repayment at the applicable Liquidation Amount becomes immediately due on demand. If Event of Default has not occurred, Holders cannot accelerate repayment.

• Phase II Notes are Senior to Phase I Notes: In the event that the Company is obligated, or elects, to repay the 2019 Convertible Notes and does not have sufficient funds to repay all Notes in full, payments shall be made in the following order: first, to the holders of Phase II Notes until each holder has received a repayment equal to 2.0 times (2.0x) the then outstanding principal balance of holder’s Phase II Notes; second, to the holders of Phase I Notes until each holder has received a repayment equal to 1.0 times (1.0x) the then outstanding principal balance of those holder’s Phase I Notes; and third, to all holders of the 2019 Convertible Notes, pro rata based on the remaining amount due to each holder pursuant to the terms and provisions of each 2019 Convertible Note held by that holder.

Concurrent to issuance of the Phase II Notes, the Company entered into subscription agreements to sell Preferred Units to the Holders equal to the principal balance of the Phase II Notes at a price of $0.50 per unit. Phase II cash proceeds totaled $11,991. The proceeds were allocated to the Phase II Notes and Preferred Units based on their relative fair values at the date of issuance. The Company recognized $2,031 attributable to the Phase II Preferred Units, which was recorded as a discount against the Phase II Notes. Refer to Note 13 for further discussion regarding the Preferred Units.

Beneficial Conversion Features

The conversion option on the Phase I Notes generated a beneficial conversion feature (BCF). A BCF arises when a debt or equity security is issued with an embedded conversion option that is in the money at inception because the conversion option has an effective strike price that is less than the fair value of the underlying equity security at the commitment date. The Company recognized this BCF by allocating the intrinsic value of the conversion option to the Preferred Units, which resulted in a discount on the Phase I Notes. The Company amortized the discount into interest expense on the commitment date, as the Convertible Notes are immediately puttable by investors.

Embedded Derivatives

Both the occurrence of a Qualified Financing and the exercise of the holders’ put options represent events that can accelerate repayment of the 2019 Convertible Notes and involve a significant discount. Therefore, these features constitute embedded derivatives that require bifurcation pursuant to ASC 815-15, Embedded Derivatives.

In the event of a Qualified Financing occurring prior to July 31, 2019, the Phase I notes can be repaid at a 1.5x or 2.0x Liquidation Amount, thereby resulting in an embedded derivative at issuance. Embedded derivative assets with initial fair value of $181 and embedded derivative liabilities with initial fair value of $1,145 were recognized during 2019. These amounts were recorded as premiums and discounts on the Convertible Notes. As of December 31, 2019, the embedded derivatives were classified as current liabilities on the consolidated balance sheet and had a fair value of $1,681. As a result, a change in fair value of embedded derivative loss of $1,718 has been recognized within other income and expense on the consolidated statement of operations during the year ended December 31, 2019. Amortization of the premium is discussed below.

The Company accounted for the 2019 Convertible Notes as deeply discounted zero coupon debt instruments. The balances payable at maturity reflect liquidation multiples of 3.0 and 6.0 times the stated face value of the Phase I and Phase II Notes, respectively. The following balances were recognized upon issuance of the Phase I and Phase II Notes:

	Phase 1			Phase 2			Total
Convertible notes payable	$	40,587		$	35,973		$	76,560
Discount, original issuance		(20,946	)		(23,982	)		(44,928	)
Premium (Discount), embedded derivative		181			(1,145	)		(964	)
Discount, fair value of preferred units		—			(2,031	)		(2,031	)
Discount, beneficial conversion features		(1,799	)		—			(1,799	)
Convertible notes payable, net	$	18,023		$	8,815		$	26,838

Subsequent Measurement

With respect to the Phase I Notes, the holders’ put option is immediately exercisable at the 1.5 times the Notes. Pursuant to ASC 470-10, which states that notes with demand features should be stated at or near the amount of cash that could be required to satisfy, a corresponding portion of the discount was amortized into interest expense immediately following issuance. Additionally, the discount attributable to the BCF was immediately amortized into interest expense at issuance. The remaining discount on the Phase I Notes was amortized into interest expense using the effective interest method through July 31, 2019, the date at which the note becomes payable at 3.0 times the outstanding principal amount.

Discounts on the Phase II Notes were amortized into interest expense using the effective interest method through the stated maturity date of October 31, 2019. On October 31, 2019, the Company defaulted under the Phase II note agreements, at which time the note holders’ put option became exercisable. Accordingly, discounts on Phase II Notes issued subsequent to October 31, 2019 were immediately amortized into interest expense upon issuance.

At issuance, the annual effective interest rates on the Phase I Notes were in excess of 400%. The Phase II Notes were issued with annual effective interest rates in excess of 1200%. During the year ended December 31, 2019, the Company recognized interest expense of $22,564 and $27,158 related to the 2019 Phase I and Phase II Notes, respectively.

As of December 31, 2019, the 2019 Convertible Notes are convertible to approximately 8.9 million and 13.8 million Preferred Units of the Company, respectively. The balances attributable to the 2019 Convertible Notes on December 31, 2019 are as follows:

	Phase 1			Phase 2			Total
Convertible notes payable	$	40,587		$	35,973		$	76,560
Discount, original issuance		(20,946	)		(23,982	)		(44,928	)
Discount, embedded derivative		181			(1,145	)		(964	)
Discount, fair value of preferred units		—			(2,031	)		(2,031	)
Discount, beneficial conversion features		(1,799	)		—			(1,799	)
Discount, accumulated amortization		22,564			27,158			49,722
Convertible notes payable, net	$	40,587		$	35,973		$	76,560

As of December 31, 2019, aggregate Phase I and Phase II Notes attributable to AltEnergy totaled $24,415.

Long-term Debt

9 Months Ended

Sep. 30, 2020

Long-term Debt

12. Long-term Debt

The following is a summary of the Company's long-term indebtedness (in thousands):

	September 30, 2020			December 31, 2019
Paycheck Protection Program loan payable	$	1,257		$	—
Other		146			—
Total		1,403			—
Less: long-term debt, current portion		(912	)		—
Long-term debt	$	491		$	—

Paycheck Protection Program

On April 7, 2020, the Company received $1,257 related to its filing under the Paycheck Protection Program and Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act"). The payment terms of the note are as follows:

• No payments during the deferral period, which is defined as the six-month period beginning on the date of the note of April 7, 2020.

• Commencing one month after the expiration of the deferral period, and continuing on the same day of each month thereafter until the maturity date, the Company shall pay to JPMorgan Chase Bank, N.A. (the "Lender"), monthly payments of principal and interest, each in such equal amount required to fully amortize the principal amount outstanding on the note on the last day of the deferral period by the maturity date (twenty-four months from the date of the note, or April 7, 2022).

• On the maturity date, the Company shall pay the Lender any and all unpaid principal plus accrued and unpaid interest plus interest accrued during the deferral period.

• The Company may prepay this note at any time without payment of any premium.

The Lender is participating in the Paycheck Protection Program to help businesses impacted by the economic impact from COVID-19. Forgiveness of this loan is only available for principal that is used for the limited purposes that qualify for forgiveness under the Small Business Administration's (the "SBA") requirements. To obtain forgiveness, the Company must request it and must provide documentation in accordance with the Small Business Administration (the "SBA") requirements, and certify that the amounts the Company is requesting to be forgiven qualify under those requirements. Forgiveness of the loan is dependent upon approval of the SBA.

At September 30, 2020, the Company owes the Lender $1,257.

Classes of Members' Capital	9 Months Ended	12 Months Ended
Classes of Members' Capital	Sep. 30, 2020	Dec. 31, 2019
EOS ENERGY STORAGE, LLC [Member]
Classes of Members' Capital	13. Classes of Members’ Capital Pursuant to the Company’s Sixth Amended and Restated Limited Liability Company Agreement (the “LLC Agreement”), Eos is authorized to issue equity units under four classes of members’ interest: Preferred Units, Common Units, Employee Units, and Service Provider Units. As of December 31, 2019, the Company has issued only Preferred Units and Common Units. As of September 30, 2020 and December 31, 2019, there were 68,190,000 Common Units outstanding. The Company’s Preferred Units are discussed at Note 14.	12. Classes of Members’ Capital Pursuant to the Company’s Sixth Amended and Restated Limited Liability Company Agreement (the “LLC Agreement”), Eos is authorized to issue equity units under four classes of members’ interest: Preferred Units, Common Units, Employee Units, and Service Provider Units. As of December 31, 2019, the Company has issued only Preferred Units and Common Units. As of December 31, 2019 and 2018, there were 68,190,000 Common Units outstanding. The Company’s preferred units are discussed at Note 13.

Contingently Redeemable Preferred Units

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Contingently Redeemable Preferred Units

14. Contingently Redeemable Preferred Units

As of September 30, 2020, the Company has outstanding Series C, Series D, and 2019-2020 Bridge Preferred Units, which were issued at $1.10, $1.75, and $0.50 per unit, respectively.

Pursuant to the LLC Agreement, the rights and privileges of the Preferred Members are as follows:

Voting — The Preferred Members are entitled to vote together with the holders of Common Units on all matters submitted for members’ vote. Additionally, the Preferred Members occupy a majority of the seats of the Board of Directors and can therefore control all decisions subject to the Board’s vote.

Preferred Members possess substantial decision-making power with respect to Company’s operations and capital structure. The following actions require a majority vote of the Preferred Members:

• Pay any dividend on any Units

• Agree or enter into a merger, sale of a material portion of the Assets, or other corporate reorganization or acquisition or any other transaction resulting in a change of control of the Company.

• Create or authorize the creation of any debt security, guarantee, or instrument with similar effect in excess of $1 million, outside the normal course of business.

• Enter new lines of business or exit the current line of business.

• Enter into an exclusive agreement or arrangement to manufacture or sell the Company’s technology.

• Sell, assign, transfer, pledge, or encumber material technology or material intellectual property.

• Take any action which deviates from the current budget approved by the Board of Directors by more than 15%.

Preferred Liquidation Preference — In the event of the termination of the Company or a Company Sale (as defined within the LLC agreement) the holders of the Preferred Units are entitled to receive for each outstanding unit an amount equal to the greater of: 1) the original issuance price per unit plus an 8% liquidation preference, accrued from the issuance date and (2) the amount which would have been payable to such Preferred Member had the Preferred Units been converted into Common Units in connection with a termination or Company Sale.

After payment of the Preferred Liquidation Preference, any remaining proceeds are distributed proportionally to the Common Unit holders. A Company Sale is defined as a sale of Units, sale of Assets, merger, recapitalization, reorganization or otherwise, pursuant to which one or more third parties (other than Voting Members) shall own in excess of fifty percent of the Voting Units or assets of the Company. As of September 30, 2020 and December 31, 2019, the Preferred Liquidation Preference was $156,936 and $136,816, respectively. Because the occurrence of a Company Sale is not probable, the Company concluded the Preferred Units are not probable of becoming redeemable. Therefore, the carrying value has not been remeasured to the Preferred Liquidation Preference.

The occurrence of a Company Sale requires the approval of both the Board of Directors and Preferred Members. Therefore, the liquidation provisions are considered contingent redemption provisions as there are certain elements that are not solely within the control of the Company. Accordingly, the Preferred Units have been presented in the mezzanine section of the consolidated balance sheet.

Conversion — The Preferred Units are convertible at any time, at the option of the holder, into Common Units of the Company. Upon an optional conversion, distributions payable on such Preferred Units that have been declared but remain unpaid, shall be converted into Common Units. Upon the closing of a Qualified Public Offering (as defined within the LLC Agreement), Preferred Units will automatically convert to common stock.

The Preferred Units are initially convertible on a one-to-one basis into Common Units, subject to certain adjustments for unit splits and combinations. The Preferred Units are also subject to full-ratchet, anti-dilution price protection (a “down round” provision). Under that provision, if the Company issues Common Units at an effective price that is less than the conversion price (the “Dilutive Price”), then the conversion price of the Preferred Units is automatically reduced to be equal to the Dilutive Price. The effect of that reduction is that, upon the issuance of either Common Units or securities convertible into Common Units, at a Dilutive Price, the Preferred Units would be convertible into a greater number of Common Units.

2019 Bridge Preferred Units

As discussed at Note 11, the Company entered into subscription agreements to sell Preferred Units to the Holders at a price of $0.50 per unit concurrently with the issuance of the 2019 Phase II Notes, which resulted in the issuance of approximately 12,000,000 Preferred Units (the “2019 Bridge Preferred Units”). The Company recognized $2,031 attributable to the 2019 Bridge Preferred Units based on the allocated fair value of cash proceeds.

Upon the issuance of 2019 Bridge Preferred Units the down round provision was triggered for the Series C and Series D Preferred Units whereby the conversion price was adjusted from $1.10 and $1.75, respectively to $0.50 per Common Unit, which resulted in approximately 144,200,000 additional Common Units being issuable upon conversion of the Series C and Series D Preferred Units. As the fair value of a Common Unit was determined to be less than $0.50 on both 1) the original issuance date of the Series C and Series D Preferred Units and 2) immediately following the issuance of the Bridge Preferred Units, the down round did not trigger a BCF. Therefore, a deemed dividend was not recognized.

As of September 30, 2020 and December 31, 2019, the Preferred Units were convertible into approximately 250,500,000 and 224,900,000 Common Units, respectively. During the periods ended September 30, 2020 and 2019, activity attributable to the Preferred Units was as follows:

	Preferred Units
	Units	Amount
Balance, December 31, 2019	80,707	$	109,365
Contributions allocated to preferred units	10,598		1,759
Issuance of preferred units	15,000		7,500
Balance, September 30, 2020	106,305	$	118,624

	Preferred Units
	Units	Amount
Balance, December 31, 2018	68,716	$	105,548
Discount on convertible notes, beneficial conversion feature	—		1,799
Contributions allocated to preferred units	7,506		1,289
Balance, September 30, 2019	76,222	$	108,636

Refer to Note 11 for further discussion regarding the fair value allocated to the Preferred Units.

13. Contingently Redeemable Preferred Units

As of December 31, 2019, the Company has outstanding Series C, Series D, and 2019 Bridge Preferred Units, which were issued at $1.10, $1.75, and $0.50 per unit, respectively.

Pursuant to the LLC Agreement, the rights and privileges of the Preferred Members are as follows:

Voting — The Preferred Members are entitled to vote together with the holders of Common Units on all matters submitted for members’ vote. Additionally, the Preferred Members occupy a majority of the seats of the Board of Directors and can therefore control all decisions subject to the Board’s vote.

The following actions require a majority vote of the Preferred Members:

• Pay any dividend on any Units

• Agree or enter into a merger, sale of a material portion of the Assets, or other corporate reorganization or acquisition or any other transaction resulting in a change of control of the Company.

• Create or authorize the creation of any debt security, guarantee, or instrument with similar effect in excess of $1,000,000, outside the normal course of business.

• Enter new lines of business or exit the current line of business.

• Enter into an exclusive agreement or arrangement to manufacture or sell the Company’s technology.

• Sell, assign, transfer, pledge, or encumber material technology or material intellectual property.

• Take any action which deviates from the current budget approved by the Board of Directors by more than 15%.

Preferred Liquidation Preference — In the event of the termination of the Company or a Company Sale (as defined within the LLC agreement) the holders of the Preferred Units are entitled to receive for each outstanding unit an amount equal to the greater of: 1) the original issuance price per unit plus an 8% liquidation preference, accrued from the issuance date and (2) the amount which would have been payable to such Preferred Member had the Preferred Units been converted into Common Units in connection with a termination or Company Sale.

After payment of the Preferred Liquidation Preference, any remaining proceeds are distributed proportionally to the Common Unit holders. A Company Sale is defined as a sale of Units, sale of Assets, merger, recapitalization, reorganization or otherwise, pursuant to which one or more third parties (other than Voting Members) shall own in excess of fifty percent of the Voting Units or assets of the Company. As of December 31, 2019 and 2018, the Preferred Liquidation Preference was $136,816 and $121,870, respectively. Because the occurrence of a Company Sale is not probable, the Company concluded the Preferred Units are not probable of becoming redeemable. Therefore, the carrying value has not been remeasured to the Preferred Liquidation Preference.

Conversion — The Preferred Units are convertible at any time, at the option of the holder, into Common Units of the Company. Upon an optional conversion, distributions payable on such Preferred Units that have been declared but remain unpaid, shall be converted into Common Units. Upon the closing of a Qualified Public Offering (as defined within the LLC Agreement), Preferred Units will automatically convert to common stock.

2019 Bridge Preferred Units

As discussed at Note 11, the Company entered into subscription agreements to sell Preferred Units to the Holders a price of $0.50 per unit concurrently with the issuance of the 2019 Phase II Notes, which resulted in the issuance of approximately 12,000,000 Preferred Units (the “2019 Bridge Preferred Units”). The Company recognized $2,031 attributable to the 2019 Bridge Preferred Units based on the allocated fair value of cash proceeds.

Upon the issuance of 2019 Bridge Preferred Units, the down round provision was triggered for the Series C and Series D Preferred Units whereby the conversion price was adjusted from $1.10 and $1.75, respectively to $0.50 per Common Unit, which resulted in approximately 144,200,000 additional Common Units being issuable upon conversion of the Series C and Series D Preferred Units. As the fair value a Common Unit was determined to be less than $0.50 on both 1) the original issuance date of the Series C and Series D Preferred Units and 2) immediately following the issuance of the Bridge Preferred Units, the down round did not trigger a BCF. Therefore, a deemed dividend was not recognized.

As of December 31, 2019 and 2018, the Preferred Units were convertible into approximately 224,900,000 and 68,700,000 Common Units, respectively. During the years ended December 31, 2019 and 2018, activity attributable to the Preferred Units was as follows:

	Preferred Units
	Units	Amount
Balance, December 31, 2017	50,970	$	74,776
Contributions	14,367		24,854
Conversion of notes payable	3,379		5,918
Balance, December 31, 2018	68,716	$	105,548
Contributions allocated to preferred units	11,991		2,031
Discount on convertible notes, beneficial conversion feature	—		1,786
Balance, December 31, 2019	80,707	$	109,36

Stock-Based Compensation

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Concentration of Credit Risk

Stock-Based Compensation

15. Stock-Based Compensation

Since 2012, Eos has issued stock options to employees and certain service providers under the 2012 Eos Equity Incentive Plan ("Plan"). In addition to stock options, the Plan provides for the issuance of other forms of stock-based compensation, including profits interests, unit appreciation rights and restricted units. As of September 30, 2020, only stock options and restricted units have been issued under the Plan.

The following table summarizes stock option activity during the nine months ended September 30, 2020:

	Units		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (years)
Options Outstanding at December 31, 2019	6,815,603		$	0.87	5.4
Granted	3,623,107		$	0.50
Cancelled/Forfeited	(3,721,897	)	$	1.10
Options Outstanding at September 30, 2020	6,716,813		$	0.54	8.8
Options Exercisable at September 30, 2020	944,993		$	0.73

As of September 30, 2020 and December 31, 2019, 0 and 1,525,147 shares remain for future issuance, respectively. 26,825,000 additional options have been awarded and will become granted upon modification of the Plan. The Company anticipates modifying the Plan in connection with the closing of its merger with B Riley Principal Merger Corporation II (BRPMC). Options vest generally over three to five years and have a term of five to ten years.

During the nine months ended September 30, 2020, the Company granted stock options with both service and performance conditions. Stock compensation is recognized over the vesting period based on the probability of achievement of the performance condition. The performance conditions primarily relate to the completion of project milestones, achievement of operational certifications, and the Company's closing of subsequent financing rounds.

The Company's Restricted Units (RU) represent the right to receive one common unit, subject to vesting and transferability restrictions. As of September 30, 2020, 1,623,937 million RUs were issued and outstanding. The RUs were measured at their grant-date fair value of $0.33 per unit, and are fully vested as of September 30, 2020.

The Company recorded stock compensation expense of $270 and $105 for the nine months ended September 30, 2020 and 2019, respectively, which has been recorded in General and administrative expenses in the Statements of Operations. Unrecognized stock compensation expense of $598 is expected to be amortized over the next four years.

The weighted average assumptions used to determine the fair value of options granted in the nine months ended September 30, 2020 and year ended December 31, 2019 are as follows:

	2020		2019
Volatility	47.91	%	58.20	%
Risk free interest rate	0.43	%	1.89	%
Expected life (years)	6.25		6.25
Dividend yield	0	%	0	%

The weighted average grant date fair value of all options granted was $0.18 and $0.07 per option for the nine months ended September 30, 2020 and year ended December 31, 2019, respectively.

14. Stock-Based Compensation

Since 2012, Eos has issued stock options to employees and certain service providers under the 2012 Eos Equity Incentive Plan (“Plan”). In addition to stock options, the Plan provides for the issuance of other forms of stock-based compensation, including profits interests, unit appreciation rights and restricted units. Only stock options have been issued under the Plan.

The following table summarizes stock option activity during the years ended December 31, 2019 and 2018:

	Units		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (years)
Options Outstanding at December 31, 2017	3,879,955		$	1.39
Granted	1,708,806		$	1.75
Cancelled/Forfeited	(331,334	)	$	1.55
Options Outstanding at December 31, 2018	5,257,427		$	1.51	2.8
Granted	4,422,114		$	0.55
Cancelled/Forfeited	(2,863,938	)	$	1.51
Options Outstanding at December 31, 2019	6,815,603		$	0.87	5.4
Options Exercisable at December 31, 2018	3,303,608		$	1.33	2.8
Options Exercisable at December 31, 2019	2,356,348		$	1.31	1.8

As of December 31, 2019 and 2018, 1,525,147 and 3,083,323 shares remain for future issuance, respectively. Options vest generally over three to five years and have a term of five to ten years. The Company recorded stock compensation expense of $135 and $137 for the years ended December 31, 2019 and 2018, respectively, which has been recorded in General and administrative expenses in the Statements of Operations. Unrecognized stock compensation expense of $365 is expected to be amortized over the next four years.

The weighted average assumptions used to determine the fair value of options granted in 2019 and 2018 are as follows:

	2019		2018
Volatility	58.20	%	62.00	%
Risk free interest rate	1.89	%	2.42	%
Expected life (years)	6.25		4.5
Dividend yield	0	%	0	%

The weighted average grant date fair value of all options granted was $0.07 and $0.12 per option for the years ended December 31, 2019 and 2018, respectively.

The following table summarizes non-vested stock option activity for the years ended December 31, 2019 and 2018:

	Shares		Fair Value
Non-vested options outstanding at December 31, 2017	828,197		$	1.49
Granted	1,708,806		$	1.75
Vested	(622,035	)	$	1.60
Exercised	—			—
Forfeited	(93,730	)	$	1.38
Non-vested options outstanding at December 31, 2018	1,821,239
Granted	4,422,114		$	0.50
Vested	(497,189	)	$	0.77
Exercised	—			—
Forfeited	(1,912,390	)	$	1.65
Non-vested options outstanding at December 31, 2019	3,833,774		$	1.72

Subsequent Events	2 Months Ended	9 Months Ended	12 Months Ended
Subsequent Events	Feb. 14, 2020	Sep. 30, 2020	Dec. 31, 2019
SUBSEQUENT EVENTS	Note 6 — Subsequent Events The Company evaluated subsequent events and transactions that occurred after the balance sheet date and through March 2, 2020, the date that the financial statements were issued. The Company did not identify any subsequent events that would have required adjustment or disclosure in the financial statements.	NOTE 7 — SUBSEQUENT EVENTS The Company evaluates subsequent events and transactions that occur after the balance sheet date up to the date that the financial statements were issued. The Company did not identify any subsequent events that would have required adjustment or disclosure in the financial statements.
EOS ENERGY STORAGE, LLC [Member]
SUBSEQUENT EVENTS		16. Subsequent Events The Company has performed an evaluation of subsequent events through November 13, 2020, the date the financial statements were issued. On August 10, 2020, the Company entered into a memorandum of agreement with Holtec Power, Inc. ("Holtec"), its joint venture partner under which Holtec has subscribed to an equity investment in the Company of $10 million. As of September 30, 2020, Holtec had funded $7.5 million of the subscribed amount. The remaining $2.5 million was funded on October 16, 2020.	15. Subsequent Events The Company has performed an evaluation of subsequent events through September 10, 2020, the date the financial statements were issued. On June 24, 2020, B. Riley Principal Merger Corp. II (NYSE: BMRG, BMRG WS, BMRG.U) (“BMRG”), a special purpose acquisition company sponsored by an affiliate of B. Riley Financial, Inc. (NASDAQ: RILY) (“B. Riley Financial”), and Eos executed a letter of intent (“LOI”) for a business combination transaction (“transaction”) which would result in Eos becoming a publicly listed company. BMRG is an acquisition company incorporated for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses. On September 7, 2020, the Eos entered into a merger agreement with BMRG for the transaction. The contemplated deal with BMRG would provide all holders of common and preferred, and Convertible notes payable — related party to receive common stock of the continuing public company, which will be a wholly owned subsidiary of BMRG. The proposed transaction is expected to be completed in the fourth quarter of 2020, subject to, among other things, the approval by BMRG’s shareholders, satisfaction of the conditions stated in the merger agreement and other customary closing conditions. There is no assurance that the transaction will be consummated. On August 10, 2020, the Company entered into a memorandum of agreement with Holtec Power, Inc. (“Holtec”), its joint venture partner under which Holtec has subscribed to an equity investment in the Company of $10 million. As of September 10, 2020, Holtec has funded $4 million of the subscribed amount. The remaining $6 million is expected to be funded prior to the close of the Company’s proposed business combination with BMRG. As of September 10, 2020, the Company issued approximately $4,850 of its 2019 Phase II Notes and $4,850 million in preferred units at $0.50 per unit. In early 2020, an outbreak of the novel strain of coronavirus (COVID-19) emerged globally. As a result, there have been mandates from federal, state and local authorities resulting in an overall decline in economic activity. As of September 10, 2020, COVID-19 has not had a material effect on the Company; third-party product safety certification from Underwriter Laboratories (UL) for the Eos Aurora Gen 2.3 150\|600 DC Battery System has been delayed due to COVID-19 and is expected in the fourth quarter of 2020. However, if COVID-19 broadly resurfaces in the latter part of 2020, it could affect the Company’s ability to install and commission its battery systems. The Company is currently evaluating the potential impact to its supply chain and is mitigating risk by developing a strategy to diversify suppliers if required.

Summary of Significant Accounting Policies (Policies)

2 Months Ended

9 Months Ended

12 Months Ended

Feb. 14, 2020

Sep. 30, 2020

Dec. 31, 2019

Basis of Presentation

The financial statements of the Company are presented in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

Basis of Presentation

The financial statements of the Company are presented in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Securities Exchange Act of 1934, as amended) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that a company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such an election to opt out is irrevocable. The Company has elected not to opt out of such extended transition period which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company, as an emerging growth company, can adopt the new or revised standard at the time private companies adopt the new or revised standard.

Emerging Growth Company

Loss Per Common Share

Net Loss Per Common Share

Loss Per Common Share

Financial Instruments

Reconciliation of Income (Loss) Per Common Share

	Three Months Ended September 30, 2020			Three Months Ended September 30, 2019		Nine Months Ended September 30, 2020			Period from June 3, 2019 (Inception) through September 30, 2019
Net loss	$	(1,961,854	)	$	—	$	(2,047,597	)	$	—
Less: Loss attributable to common stock subject to possible redemption		(31,646	)		—		(41,955	)		—

Adjusted net loss	$	(1,993,500	)	$	—	$	(2,089,552	)	$	—

Weighted average shares outstanding, basic and diluted		5,450,881			5,000,000		7,654,134			5,000,000

Basic and diluter loss per common share	$	(0.37	)	$	—	$	(0.27	)	$	—

Cash and Cash Equivalents

Class A Common Stock Subject To Possible Redemption

Concentration of Credit Risk

Use of Estimates

Fair Value of Financial Instruments

Offering Costs

Income Taxes

The provision for income taxes was deemed to be immaterial at December 31, 2019 and February 14, 2020.

Income Taxes

ASC Topic 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. As of September 30, 2020 and December 31, 2019, there were no unrecognized tax benefits and no amounts accrued for interest and penalties. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position.

Unrecognized Tax Benefits

Recent Accounting Standards

Recent Accounting Pronouncements

Management does not believe that any recently issued, but not yet effective, accounting pronouncements, if currently adopted, would have a material effect on the Company’s financial statements.

Recent Accounting Standards

Management does not believe that any recently issued, but not yet effective, accounting standards updates, if currently adopted, would have a material effect on the Company’s financial statements.

Liquidity and Going Concern

Nature of Operations

Basis of Presentation

The financial statements include the accounts of the Company and have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).

Basis of Presentation

The financial statements include the accounts of the Company and have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).

Deferred Transaction Costs

Concentration of Credit Risk

Eos maintains cash balances at FDIC-insured institutions. However, the FDIC limits may be exceeded at times. The Company has not experienced any losses on such accounts.

Concentration of Credit Risk

Eos maintains cash balances at FDIC-insured institutions However, the FDIC limits may be exceeded at times. The Company has not experienced any losses on such accounts.

Cash and Cash Equivalents

Cash and cash equivalents include cash and highly liquid investments purchased with original maturities of three months or less.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Income Taxes and Deferred Taxes

Impairment of Long - Lived Assets

Impairment of Long — Lived Assets

Intangible Assets

Intangible assets are stated at their historical cost and amortized on a straight-line basis over their expected useful lives.

Property and Equipment

Risks and Uncertainties

Revenue from Contracts with Customers

Risks and Uncertainties

Revenue from Contracts with Customers

Revenue from Contracts with Customers

Revenue is earned from the sales, installation, and commissioning of energy storage systems and is derived from customer contracts. Revenue is recognized in an amount that reflects the consideration to which the Company expects to be entitled in exchange for transferring the promised goods and/or services to the customer, when or as the Company’s performance obligations are satisfied. For product sales of energy storage systems, the Company’s performance obligations are satisfied at the point in time when the customer obtains control of the system, which is either upon delivery of the goods at the customer’s designated location or upon the customer’s acceptance of the product after commissioning and testing at the customer’s site, depending on the specific terms of the respective contract with the customer. In addition, the corresponding installation and commissioning services related to the systems are performance obligations satisfied over time as the respective services are performed, based on an input measure of progress as labor costs relating to the installation and commissioning services are incurred. Further, extended warranties are offered by the Company and are identified as performance obligations that are satisfied over time, based on a time-elapsed measure of progress resulting in a ratable recognition of revenue over the respective warranty period. Payment terms generally include advance payments to reserve capacity and/or upon issuance of the customer’s purchase order, shipment readiness, with the remainder upon delivery and commissioning of the system. Shipping and handling costs are included in cost of sales. Sales tax collected from customers are recorded on a net basis and therefore, not included in revenue. Sales tax is recorded as a liability (payable) until remitted to governmental authorities.

Revenue from Contracts with Customers

Revenue is earned from the sales, installation, and commissioning of energy storage systems and is derived from customer contracts. Revenue is recognized in an amount that reflects the consideration to which the Company expects to be entitled in exchange for transferring the promised goods and/or services to the customer, when or as the Company’s performance obligations are satisfied. For product sales of energy storage systems, the Company’s performance obligations are satisfied at the point in time when the customer obtains control of the system, which is either upon delivery of the goods at the customer’s designated location or upon the customer’s acceptance of the product after commissioning and testing at the customer’s site, depending on the specific terms of the respective contract with the customer. In addition, the corresponding installation and commissioning services related to the systems are performance obligations satisfied over time as the respective services are performed, based on an input measure of progress as labor costs relating to the installation and commissioning services are incurred. Further, extended warranties are offered by the Company and are identified as performance obligations that are satisfied over time, based on a time-elapsed measure of progress resulting in a ratable recognition of revenue over the respective warranty period. Payment terms generally include advance payments to reserve capacity and/or upon issuance of the customer’s purchase order, shipment readiness, with the remainder upon delivery and commissioning of the system. Shipping and handling costs are included in cost of sales. Sales tax collected from customers are recorded on a net basis and therefore, not included in revenue. Sales tax is recorded as a liability (payable) until remitted to governmental authorities.

The Company may enter into sales contracts that provide for performance obligations in addition to the sale of the product, including performance guarantees and service obligations. Under these sales contracts, transaction price is allocated to the various performance obligation based on the relative stand-alone selling prices of the promised goods and services. When the stand-alone selling price is not observable, revenue related to service type warranties is determined based on a best estimate of selling price using cost plus a reasonable margin and is recognized ratably over the period of performance.

Royalty Revenue

Product Warranty

Government Grants

Research and Development Expenses

Research and development costs are expensed as incurred, which include materials, supplies, salaries, benefits and other costs related to research, development and testing of products.

Rent Expense

Accounts Receivable

Inventory

Investment in unconsolidated joint venture

Stock-Based Compensation

Segments

Fair Value of Financial Instruments

The Company’s financial instruments consist of cash and cash equivalents, accounts receivable, accounts payable, and notes payable — related party.

As of December 31, 2018, the carrying value of the Company’s notes payable and convertible notes payable — related party of $1,000 and $2,350, respectively, approximate their fair values.

Refer to Note 11 for further discussion of the convertible notes payable — related party and the embedded derivatives.

Recent Accounting Standards

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2020

Summary of Significant Accounting Policies [Abstract]

Schedule of basic and diluted loss per share

	Three Months Ended September 30, 2020			Three Months Ended September 30, 2019		Nine Months Ended September 30, 2020			Period from June 3, 2019 (Inception) through September 30, 2019
Net loss	$	(1,961,854	)	$	—	$	(2,047,597	)	$	—
Less: Loss attributable to common stock subject to possible redemption		(31,646	)		—		(41,955	)		—

Adjusted net loss	$	(1,993,500	)	$	—	$	(2,089,552	)	$	—

Weighted average shares outstanding, basic and diluted		5,450,881			5,000,000		7,654,134			5,000,000

Basic and diluter loss per common share	$	(0.37	)	$	—	$	(0.27	)	$	—

Revenue Recognition (Tables) - EOS ENERGY STORAGE, LLC [Member]

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Schedule of liabilities from contracts with customers

		September 30, 2020			December 31, 2019			September 30, 2019			December 31, 2018
Contract Liabilities		$	310		$	300		$	817		$	718

		September 30, 2020			December 31, 2019			September 30, 2019			December 31, 2018
Contract Liabilities		$	310		$	300		$	817		$	718

Schedule of estimated revenue expected to be recognized in the future related to performance obligations

September 30, 2020		2020			2021			2022			2023			Thereafter
Product Revenue		$	310		$	—		$	—		$	—		$	—

September 30, 2020		2020			2021			2022			2023			Thereafter
Product Revenue		$	310		$	—		$	—		$	—		$	—

Property and Equipment (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Schedule of property and equipment

	2020			2019			Useful lives
Equipment	$	7,039		$	5,910		5 – 10 years
Capital lease		201			201		5 years
Furniture		176			125		5 – 10 years
Leasehold Improvements		2,732			2,732		Lesser of useful life/remaining lease
Tooling		588			150		2 – 3 years
Total		10,736			9,118
Less: Accumulated Depreciation and Amortization		(4,919	)		(3,802	)
	$	5,817		$	5,316

	2019			2018			Useful lives
Equipment	$	5,910		$	9,438		5 – 10 years
Capital lease		201			225		5 years
Furniture		125			186		5 – 10 years
Leasehold Improvements		2,732			3,130		Lesser of useful life/remaining lease
Construction in progress		—			50
Tooling		150			907		2 – 3 years
Total		9,118			13,936
Less: Accumulated Depreciation and Amortization		(3,802	)		(7,394	)
	$	5,316		$	6,542

Intangible Assets (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Schedule of future amortization expense of intangible assets

Remainder of 2020	$	10
2021		40
2022		40
2023		40
2024		40
Thereafter		160
	$	330

2020	$	40
2021		40
2022		40
2023		40
2024		40
Thereafter		160
	$	360

Commitments and Contingencies (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Schedule of future minimum lease commitments

	Operating		Capital
Remainder of 2020	$	167	$	4
2021		685		15
2022		755		6
2023		825		—
2024		895		—
Later years		1,644		—
Total minimum lease payments	$	4,971	$	25
Less amounts representing interest				3
Present value of minimum lease payments			$	22

	Operating		Capital
2020	$	614	$	13
2021		685		13
2022		755		4
2023		825		—
2024		895		—
Later years		1,644		—
Total minimum lease payments	$	5,418	$	30
Less amounts representing interest				5
Present value of minimum lease payments			$	25

Convertible Notes Payable (Tables) - EOS ENERGY STORAGE, LLC [Member]

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Schedule of convrtible notes recognized upon issuance

							September 30, 2020 Phase II			Total
	December 31, 2019
	Phase I			Phase II
Convertible notes payable	$	40,587		$	35,973		$	31,793		$	108,353
Discount, original issuance		(20,946	)		(23,982	)		(21,196	)		(66,124	)
Premium (discount), embedded derivative		181			(1,145	)		(411	)		(1,375	)
Discount, fair value of preferred units		—			(2,031	)		(1,759	)		(3,790	)
Discount, beneficial conversion features		(1,799	)		—			—			(1,799	)
Convertible notes payable, net	$	18,023		$	8,815		$	8,427		$	35,265

	Phase 1			Phase 2			Total
Convertible notes payable	$	40,587		$	35,973		$	76,560
Discount, original issuance		(20,946	)		(23,982	)		(44,928	)
Premium (Discount), embedded derivative		181			(1,145	)		(964	)
Discount, fair value of preferred units		—			(2,031	)		(2,031	)
Discount, beneficial conversion features		(1,799	)		—			(1,799	)
Convertible notes payable, net	$	18,023		$	8,815		$	26,838

Schedule of balances attributable to convertible notes payable

	Phase I			Phase II			September 30, 2020
Convertible notes payable	$	40,587		$	67,766		$	108,353
Discount, original issuance		(20,946	)		(45,178	)		(66,124	)
Premium (discount), embedded derivative		181			(1,556	)		(1,375	)
Discount, fair value of preferred units		—			(3,790	)		(3,790	)
Discount, beneficial conversion features		(1,799	)		—			(1,799	)
Discount, accumulated amortization		22,564			50,524			73,088
Convertible notes payable, net	$	40,587		$	67,766		$	108,353

	Phase I			Phase II			December 31, 2019
Convertible notes payable	$	40,587		$	35,972		$	76,559
Discount, original issuance		(20,946	)		(23,982	)		(44,928	)
Premium (discount), embedded derivative		181			(1,145	)		(964	)
Discount, fair value of preferred units		—			(2,031	)		(2,031	)
Discount, beneficial conversion features		(1,799	)		—			(1,799	)
Discount, accumulated amortization		22,564			27,158			49,722
Convertible notes payable, net	$	40,587		$	35,972		$	76,559

	Phase 1			Phase 2			Total
Convertible notes payable	$	40,587		$	35,973		$	76,560
Discount, original issuance		(20,946	)		(23,982	)		(44,928	)
Discount, embedded derivative		181			(1,145	)		(964	)
Discount, fair value of preferred units		—			(2,031	)		(2,031	)
Discount, beneficial conversion features		(1,799	)		—			(1,799	)
Discount, accumulated amortization		22,564			27,158			49,722
Convertible notes payable, net	$	40,587		$	35,973		$	76,560

Long-term Debt (Tables)

9 Months Ended

Sep. 30, 2020

Schedule of company’s long-term indebtedness

	September 30, 2020			December 31, 2019
Paycheck Protection Program loan payable	$	1,257		$	—
Other		146			—
Total		1,403			—
Less: long-term debt, current portion		(912	)		—
Long-term debt	$	491		$	—

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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Schedule of Income tax expense (benefit)

Income Taxes (Tables) - EOS ENERGY STORAGE, LLC [Member]

12 Months Ended

Dec. 31, 2019

	2019		2018
Current expense (benefit):
U.S. federal	$	—	$	—
U.S. state and local		—		—
Total current income tax (benefit) provision		—		—
Deferred expense (benefit):
U.S. federal	$	—	$	—
U.S. state and local		—		—
Total deferred income tax (benefit) provision		—		—
Total income tax (benefit) provision	$	—	$	—

Schedule of reconciliation of our income tax rate computed using the federal statutory rate to our actual income tax rate

	2019			2018
Income (loss) before income taxes	$	(79,483	)	$	(28,498	)
Statutory U.S. federal income tax (21%)		(16,691	)		(5,985	)
State and local income tax		1,548			768
Disallowed interest expense		11,903			—
Federal R&D credit		(1,002	)		(1,065	)
Valuation allowance		4,215			6,276
Other		27			6
Total income tax expense		—			—
Effective tax rate		0	%		0	%

Schedule of net deferred tax assets

	2019			2018
Deferred tax assets:
NOL carryforwards	$	30,540		$	26,858
Tax credit carryforwards		4,346			4,390
Employee compensation		187			211
Accruals and reserves		543			136
Organizational costs		194			24
Deferred tax assets, gross	$	35,810			31,619
Valuation allowance	$	(34,773	)		(30,558	)
Total deferred tax assets, net	$	1,037		$	1,061
Deferred tax liabilities:
Fixed assets		(1,010	)		(1,061	)
Investment in partnership		(27	)		—
Deferred tax liabilities		(1,037	)		(1,061	)
Total deferred tax asset (liability)	$	—		$	—

Contingently Redeemable Preferred Units (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Schedule of activity attributable to the preferred units

	Preferred Units
		Units	Amount
Balance, December 31, 2019		80,707	$	109,365
Contributions allocated to preferred units		10,598		1,759
Issuance of preferred units		15,000		7,500
Balance, September 30, 2020		106,305	$	118,624

	Preferred Units
	Units	Amount
Balance, December 31, 2018	68,716	$	105,548
Discount on convertible notes, beneficial conversion feature	—		1,799
Contributions allocated to preferred units	7,506		1,289
Balance, September 30, 2019	76,222	$	108,636

	Preferred Units
	Units	Amount
Balance, December 31, 2017	50,970	$	74,776
Contributions	14,367		24,854
Conversion of notes payable	3,379		5,918
Balance, December 31, 2018	68,716	$	105,548
Contributions allocated to preferred units	11,991		2,031
Discount on convertible notes, beneficial conversion feature	—		1,786
Balance, December 31, 2019	80,707	$	109,365

Stock-Based Compensation (Tables) - EOS ENERGY STORAGE, LLC [Member]

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

Schedule of stock option activity

	Units		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (years)
Options Outstanding at December 31, 2019	6,815,603		$	0.90	5.4
Granted	3,623,107		$	0.50
Cancelled/Forfeited	(3,721,897	)	$	1.10
Options Outstanding at September 30, 2020	6,716,813		$	0.54	8.8
Options Exercisable at September 30, 2020	944,993		$	0.73

	Units		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (years)
Options Outstanding at December 31, 2017	3,879,955		$	1.39
Granted	1,708,806		$	1.75
Cancelled/Forfeited	(331,334	)	$	1.55
Options Outstanding at December 31, 2018	5,257,427		$	1.51	2.8
Granted	4,422,114		$	0.55
Cancelled/Forfeited	(2,863,938	)	$	1.51
Options Outstanding at December 31, 2019	6,815,603		$	0.87	5.4
Options Exercisable at December 31, 2018	3,303,608		$	1.33	2.8
Options Exercisable at December 31, 2019	2,356,348		$	1.31	1.8

Schedule of weighted average fair value of options granted

	2020		2019
Volatility	47.91	%	58.20	%
Risk free interest rate	0.43	%	1.89	%
Expected life (years)	6.25		6.25
Dividend yield	0	%	0	%

	2019		2018
Volatility	58.20	%	62.00	%
Risk free interest rate	1.89	%	2.42	%
Expected life (years)	6.25		4.5
Dividend yield	0	%	0	%

Schedule of non-vested stock option activity

	Shares		Fair Value
Non-vested options outstanding at December 31, 2017	828,197		$	1.49
Granted	1,708,806		$	1.75
Vested	(622,035	)	$	1.60
Exercised	—			—
Forfeited	(93,730	)	$	1.38
Non-vested options outstanding at December 31, 2018	1,821,239
Granted	4,422,114		$	0.50
Vested	(497,189	)	$	0.77
Exercised	—			—
Forfeited	(1,912,390	)	$	1.65
Non-vested options outstanding at December 31, 2019	3,833,774		$	1.72

Organization, Nature of Business Operations and Liquidity and Going Concern (Details) - USD ($)	1 Months Ended		2 Months Ended	9 Months Ended
	May 22, 2020	Feb. 04, 2020	Feb. 14, 2020	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Sponsor and note payable description		On February 4, 2020, the Sponsor agreed to loan the Company up to $300,000 (see note 4) to support the Company’s initial formation and operations.		On February 4, 2020, the Sponsor agreed to loan the Company up to $300,000 (see Note 3) to support the Company’s initial formation and operations. In February 2020, the Company borrowed $50,000 and in April 2020 the Company borrowed an additional $50,000 which increased the Note Payable balance to $100,000 which was repaid in full in connection with the closing of the Public Offering using the proceeds from the Public Offering and the Private Placement.
Sponsor and proposed financing, description		The Company’s ability to commence meaningful operations and finance its Initial Business Combination is contingent upon obtaining adequate financial resources through the proposed $175,000,000 ($201,250,000 if the underwriters’ over-allotment is exercised in full) initial public offering of Units (as defined below) (Note 3). Upon the closing of the Proposed Offering and the Private Placement, $176,750,000 (or $203,262,500 if the underwriters’ over-allotment option is exercised in full — Note 3) will be held in a trust account (the “Trust Account”) (discussed below).
Public offering				$ 175,000,000
Obligation to redeem percentage				100.00%
Public offering period				18 months
Interest paid				$ 100,000
Tangible assets				5,000,001
Trust account balance				176,777,682
Trust account, description			The proceeds to be held in the Trust Account will be invested only in U.S. government treasury bills with a maturity of 185 days or less or in money market funds registered under the Investment Company Act and compliant with Rule 2a-7 thereof that maintain a stable net asset value of $1.00. Unless and until the Company completes the Initial Business Combination, it may pay its expenses only from the net proceeds of the Proposed Offering held outside the Trust Account, which will be approximately $500,000 in working capital after the payment of approximately $750,000 in expenses relating to the proposed Offering, and any loans or additional investments from the Sponsor, members of the Company’s management team or any of their respective affiliates or other third parties. Except with respect to interest earned on the funds held in the Trust Account that may be released to the Company to pay its taxes, the proceeds from the Proposed Offering may not be released from the Trust Account until the earliest of: (i) the completion of the Initial Business Combination; (ii) the redemption of any public shares properly tendered in connection with a stockholder vote to amend the Company’s amended and restated certificate of incorporation to modify the substance or timing of the Company’s obligation to redeem 100% of its public shares if it does not complete the Initial Business Combination within 18 months from the closing of the Proposed Offering; or (iii) the redemption of all of the Company’s public shares if the Company is unable to complete the Initial Business Combination within 18 months from the closing of the Proposed Offering (at which such time up to $100,000 of interest shall be available to the Company to pay dissolution expenses), subject to applicable law. The proceeds deposited in the Trust Account could become subject to the claims of the Company’s creditors, if any, which could have priority over the claims of the Company’s public stockholders.
Net of tangible assets			$ 5,000,001
Dissolution expenses			100,000
Cost of energy storage			50,000
Cash			$ 50,000	315,105
Working capital deficit				1,229,514
Franchise taxes payable				$ 72,231
Class A Common Stock
Offering price			$ 11.50
Offering price				$ 11.50
Common stock par value			$ 0.0001	$ 0.0001	$ 0.0001
IPO [Member]
Sale of units	17,500,000
Offering price	$ 10.00
Purchase of aggregate units	$ 650,000
Offering price	$ 10.00
Gross proceeds	$ 175,000,000
Underwriting commissions	3,500,000
Offering costs	476,189
Private Placement [Member]
Gross proceeds	6,500,000
Public offering	1,284,805
Note Payable to Sponsor	100,000
Offering costs payment	$ 476,189
EOS ENERGY STORAGE, LLC [Member]
Cash				$ 6,534,000	$ 862,000	$ 5,498,000
Redeemable preferred units				$ 118,624
Reverse stock split				10,000 shares of the Company’s common stock were issued to B. Riley Principal Investments, LLC. On February 3, 2020, the Company conducted a 1:575 stock split and reclassification, resulting in B. Riley Principal Investments, LLC holding 5,750,000 shares of Class B common stock (the “Founder Shares”).
Total members (deficit)				$ (249,270)

Summary of Significant Accounting Policies (Details) - USD ($)

2 Months Ended

3 Months Ended

4 Months Ended

7 Months Ended

9 Months Ended

Feb. 14, 2020

Sep. 30, 2020

Sep. 30, 2019

Dec. 31, 2019

Sep. 30, 2020

Summary of Significant Accounting Policies [Abstract]

Less: Loss attributable to common stock subject to possible redemption

$ (47)

$ (1,961,854)

$ (278)

$ (2,047,597)

(31,646)

(41,955)

Adjusted net loss

$ (1,993,500)

$ (2,089,552)

Weighted average shares outstanding, basic and diluted

^[1],[2]

5,450,881

5,000,000

7,654,134

Basic and diluter loss per common share

$ (0.37)

$ 0.00

$ (0.27)

[1]	Excludes an aggregate of up to 16,878,805 shares subject to possible redemption.
[2]	Net loss per common share - basic and diluted excludes income attributable to common stock subject to possible redemption of $31,646 and $41,955 for the three and nine months ended September 30, 2020, respectively (see Note 2).

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Summary of Significant Accounting Policies (Textual)

Summary of Significant Accounting Policies (Details Textual) - USD ($)

1 Months Ended

2 Months Ended

9 Months Ended

12 Months Ended

May 22, 2020

Feb. 29, 2020

Feb. 14, 2020

Sep. 30, 2020

Dec. 31, 2019

Dec. 31, 2018

Jun. 30, 2020

^[1]

Sep. 30, 2019

Jun. 30, 2019

Jun. 04, 2019

Jun. 02, 2019

^[2]

Federal depository insurance coverage

10,000

$ 250,000

476,189

3,500,000

5,000,001

Stock split, description

The Company completed a stock split of 1 to 575 shares of Class B common stock, resulting in 5,750,000 shares of Class B common stock issued and outstanding.

$ 250,000

Total cash and cash equivalents

50,001

177,329,013

$ 1

50,000

315,105

Contingently redeemable preferred stock

50,325

1,853,076

278

$ (324)

$ 5,000,006

(277)

^[1]

$ 5,000,006

$ 1

Summary of Significant Accounting Policies (Textual)

Stock split

10,000 shares of the Company’s common stock were issued to B. Riley Principal Investments, LLC. On February 3, 2020, the Company conducted a 1:575 stock split and reclassification, resulting in B. Riley Principal Investments, LLC holding 5,750,000 shares of Class B common stock (the “Founder Shares”).

Total cash and cash equivalents

$ 22,293,000

13,057,000

$ 15,046,000

6,534,000

862,000

5,498,000

Convertible notes payable

132,469,000

87,414,000

13,872,000

108,353,000

76,559,000

2,350,000

Contingently redeemable preferred stock

Business combination, description

$ (228,800,000)

$ (183,722,000)

(104,374,000)

The Company entered into a merger agreement to merge with B. Riley Principal Merger Corp. II ("BMRG II"). BMRG II is a special acquisition company ("SPAC") incorporated for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (the "SPAC transaction"). The SPAC transaction is currently expected to close in November 2020 and would allow all holders of the Company's equity and equity-linked securities to receive common stock of the continuing public company, BMRG II. Accordingly, as part of the closing of the SPAC transaction, the Company currently expects substantially all the total amounts owed on the Company's outstanding convertible notes will be converted into shares of the continuing public company. The merger would result in a net increase in cash to the Company of between approximately $97.8 million, assuming maximum shareholder redemptions permitted under the Business Combination Agreement, and $204.6 million, assuming minimum shareholder redemption. Management plans to use these proceeds, among other things, to fund the Company's obligations as they become due. While management believes they will be able to close the SPAC transaction in the fourth quarter of 2020, no assurance can be provided that such transaction will close or on terms that are acceptable to the Company. If the Company is unable to close the SPAC transaction, management plans to obtain additional outside capital to fund the Company's current cost structure through the issuance of Series E Preferred shares and modify the terms of the Company's outstanding convertible notes to, among other things, extend the current amounts owed to future periods. While management believes they would be able to issue Series E Preferred shares and modify the terms of the Company's outstanding convertible notes in the event the SPAC transaction fails to close, no assurance can be provided that such issuance and modification will occur or on terms that are acceptable to the Company.

The Company entered into a letter of intent dated June 24, 2020 to merge with B. Riley Principal Merger Corp. II (“BMRG II”). BMRG II is a special acquisition company (“SPAC”) incorporated for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses (the “SPAC transaction”). The SPAC transaction is currently expected to close in the fourth quarter of 2020 and would allow all holders of the Company’s equity and equity-linked securities to receive a combination of common stock of the continuing public company, which will be a wholly owned subsidiary of BMRG II. Accordingly, as part of the closing of the SPAC transaction, the Company currently expects substantially all the total amounts owed on the Company’s outstanding convertible notes will be converted into shares of the continuing public company. The merger would result in a net increase in cash to the Company of between approximately $66.4 million, assuming maximum shareholder redemptions permitted under the Business Combination Agreement, and $212.3 million, assuming minimum shareholder redemption, for which management plans to use to, among other things, fund the Company’s obligations as they become due. While management believes they will be able to close the SPAC transaction in October 2020, no assurance can be provided that such transaction will close or on terms that are acceptable to the Company. If the Company is unable to close the SPAC transaction, management plans to obtain additional outside capital to fund the Company’s current cost structure through the issuance of Series E Preferred shares and modify the terms of the Company’s outstanding convertible notes to, among other things, extend the current amounts owed to future periods. While management believes they would be able to issue Series E Preferred shares and modify the terms of the Company’s outstanding convertible notes in the event the SPAC transaction fails to close, no assurance can be provided that such issuance and modification will occur or on terms that are acceptable to the Company.

Deferred transaction costs

$ 2,386,000

Impairment of long - lived assets

$ 1,590,000

1,441,000

Convertible notes payable related party

65,942,000

1,000,000

Fair value of convertible notes payable related party

76,559,000

$ 2,350,000

Fair value of the embedded derivative liability

$ 1,618,000

IPO [Member]

Summary of Significant Accounting Policies (Textual)

Sale of units

17,500,000

Class B Common Stock [Member]

Summary of Significant Accounting Policies (Textual)

5,750,000

4,375,000

5,750,000

4,375,000

5,750,000

^[3]

Stock split

1 to 575

Purchase shares

Class A Common Stock [Member]

$ 575

$ 437

$ 575

^[1]

437

575

Summary of Significant Accounting Policies (Textual)

1,271,195

1,271,195

Purchase shares

^[1]

17,500,000

Class A Common Stock [Member] | Private Placement [Member]

^[1]

$ 108

Summary of Significant Accounting Policies (Textual)

Purchase shares

9,075,000

[1]	Includes an aggregate of 750,000 shares that are subject to forfeiture to the extent that the underwriter's over-allotment is not exercised in full (Note 4). On February 3, 2020, the Company conducted a 1:575 stock split and reclassification for each share outstanding (Note 4).
[2]	Includes an aggregate of 656,250 shares that are subject to forfeiture to the extent that the underwriters over-allotment is not exercised in full (Note 4). On February 3, 2020, the Company conducted a 1:575 shares for each share outstanding (Note 4).
[3]	Includes an aggregate of 750,000 shares that are subject to forfeiture to the extent the underwriter’s overallotment is not exercised in full (Note 4).

Public Offering (Details) - $ / shares	2 Months Ended
Public Offering (Details) - $ / shares	Feb. 14, 2020	Sep. 30, 2020	Dec. 31, 2019
Numbre of public offeing shares	17,500,000
Public offering price per share	$ 10.00
Aggregate of sponsor purchased share	650,000
Over-allotment option to underwritters	728,750
Private placement unit per share	$ 10.00
Expecting to pay underwriting commissions	2.00%
Stock option to purchse pro rata basis	2,625,000
Business combination marketing agreement, description	The Company will pay B. Riley Securities, Inc. for such services upon the consummation of the Initial Business Combination a cash fee in an amount equal to 3.5% of the gross proceeds of the Proposed Offering (exclusive of any applicable finders’ fees which might become payable) ($6,125,000 or up to $7,043,750 if the underwriters’ over-allotment option is exercised in full). Pursuant to the terms of the business combination marketing agreement, no fee will be due if the Company does not complete an Initial Business Combination.
Class A Common Stock
Commonn stock par value	$ 0.0001	$ 0.0001	$ 0.0001
Price per share	$ 11.50

Revenue Recognition (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Jan. 02, 2018
EOS ENERGY STORAGE, LLC [Member]
Contract liabilities	$ 310,000	$ 300,000	$ 817,000	$ 718,000	$ 660,000

Revenue Recognition (Details 1) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Product Revenue	$ 35,000	$ 211,000	$ 496,000
2020 [Member]
Product Revenue	310,000		300,000
2021 [Member]
Product Revenue			0
2022 [Member]
Product Revenue			0
2023 [Member]
Product Revenue			0
Thereafter [Member]
Product Revenue			$ 0

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Revenue Recognition (Details Textual) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Revenue Recognition (Textual)
Contract liabilities increased/decreased	$ 10,000	$ 99,000	$ 418,000	$ 58,000
Recognized of revenue	$ 0	$ 0	$ 58,000	$ 0

Inventory (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
EOS ENERGY STORAGE, LLC [Member]
Inventory (Textual)
Inventories	$ 78,000	$ 0	$ 801,000

Property and Equipment (Details) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Total	$ 10,736,000	$ 9,118,000	$ 13,936,000
Less: Accumulated Depreciation and Amortization	(4,919,000)	(3,802,000)	(7,394,000)
Property and equipment, net	5,817,000	5,316,000	6,542,000
Equipment [Member]
Total	$ 7,039,000	$ 5,910,000	9,438,000
Equipment [Member] \| Minimum [Member]
Useful lives	5 years	5 years
Equipment [Member] \| Maximum [Member]
Useful lives	10 years	10 years
Capital lease [Member]
Total	$ 201,000	$ 201,000	225,000
Useful lives	5 years	5 years
Furniture [Member]
Total	$ 176,000	$ 125,000	186,000
Furniture [Member] \| Minimum [Member]
Useful lives	5 years	5 years
Furniture [Member] \| Maximum [Member]
Useful lives	10 years	10 years
Leasehold Improvements [Member]
Total	$ 2,732,000	$ 2,732,000	3,130,000
Useful lives, property and equipment	Lesser of useful life/remaining lease	Lesser of useful life/remaining lease
Tooling [Member]
Total	$ 588,000	$ 150,000	907,000
Tooling [Member] \| Minimum [Member]
Useful lives	2 years	2 years
Tooling [Member] \| Maximum [Member]
Useful lives	3 years	3 years
Construction in progress [Member]
Total			$ 50,000

Property and Equipment (Details Textual) - USD ($)	9 Months Ended		12 Months Ended
Property and Equipment (Details Textual) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
EOS ENERGY STORAGE, LLC [Member]
Property and Equipment (Textual)
Depreciation and amortization expense	$ 1,112,000	$ 1,740,000	$ 2,083,000	$ 2,417,000

Intangible Assets (Details) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Remainder of 2020	$ 10,000	$ 40,000
2021	40,000	40,000
2022	40,000	40,000
2023	40,000	40,000
2024	40,000	40,000
Thereafter	160,000	160,000
Intangible Assets Amortization Expense	$ 330,000	$ 360,000

Intangible Assets (Details Textual) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets (Textual)
Intangible assets	$ 330,000		$ 360,000	$ 400,000
Amortization expenses	30,000	$ 30,000	40,000	$ 0
Patents [Member]
Intangible Assets (Textual)
Intangible assets	$ 400,000		$ 400,000

Stockholders' Equity (Details) - shares

1 Months Ended

2 Months Ended

9 Months Ended

12 Months Ended

Feb. 14, 2020

Feb. 03, 2020

May 19, 2020

Apr. 21, 2020

Feb. 14, 2020

Sep. 30, 2020

Dec. 31, 2019

Feb. 29, 2020

Jun. 04, 2019

Shares are subject to forfeiture

656,250

750,000

Founder shares

80,000

Preferred stock, shares authorized

1,000,000

Stock split

1:575

Preferred stock, shares issued

10,000

Preferred stock shares outstanding

Shares are subject to possible redemption

16,878,805

Class A Common Stock

Common stock shares authorized

100,000,000

1,000,000

Common stock shares outstanding

1,271,195

1,271,195

Common Class B [Member]

Common stock shares authorized

25,000,000

Common stock shares outstanding

5,750,000

4,375,000

5,750,000

^[1]

5,750,000

Shares are subject to forfeiture

656,250

750,000

656,250

Sponsor for cancellation

718,750

Total shares

5,031,250

Forfeiture shares

656,250

Number of shares description

There were 18,150,000 shares of Class A common stock issued and outstanding.

Private Placement [Member]

5,750,000

4,375,000

5,750,000

Warrants for redemption, description

The Company may call the Warrants for redemption (except with respect to the Private Placement Warrants): • in whole and not in part; • at a price of $0.01 per warrant; • upon a minimum of 30 days’ prior written notice of redemption (the “30-day redemption period”); and • if, and only if, the last sale price of the Class A common stock equals or exceeds $18.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date on which the Company sends the notice of redemption to the warrantholders.

● in whole and not in part; ● at a price of $0.01 per warrant; ● upon a minimum of 30 days' prior written notice of redemption (the "30-day redemption period"); and ● if, and only if, the last sale price of the Class A common stock equals or exceeds $18.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date on which the Company sends the notice of redemption to the warrant holders.

Number of shares description

The exercise price and number of shares of Class A common stock issuable upon exercise of the warrants may be adjusted in certain circumstances including in the event of a share dividend, or recapitalization, reorganization, merger or consolidation. In addition, if (x) the Company issues additional shares of Class A common stock or securities convertible into or exercisable or exchangeable for shares of Class A common stock for capital raising purposes in connection with the closing of the Initial Business Combination (excluding any issuance of securities under the Forward Purchase Agreement), at an issue price or effective issue price of less than $9.20 per share of Class A common stock (with such issue price or effective issue price to be determined in good faith by the Company’s board of directors and, in the case of any such issuance to the Sponsor or its affiliates, without taking into account any Founder Shares held by the Sponsor or such affiliates, as applicable, prior to such issuance (the “Newly Issued Price”)), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for funding the Initial Business Combination, and (z) the volume weighted average trading price of the Class A common stock during the 20 trading day period starting on the trading day prior to the day on which the Company consummates the Initial Business Combination (the “Market Value”) is below $9.20 per share, the exercise price of the warrants will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger price described above will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price. Additionally, in no event will the Company be required to net cash settle any warrant. In the event that a registration statement is not effective for the exercised warrants, the purchaser of a unit containing such warrant will have paid the full purchase price for the unit solely for the share of Class A common stock underlying such unit. There will be no redemption rights or liquidating distributions with respect to the warrants, which will expire worthless if the Company fails to complete an Initial Business Combination within the 18-month time period.

The exercise price and number of shares of Class A common stock issuable upon exercise of the Warrants may be adjusted in certain circumstances including in the event of a share dividend, or recapitalization, reorganization, merger or consolidation. In addition, if (x) the Company issues additional shares of Class A common stock or securities convertible into or exercisable or exchangeable for shares of Class A common stock for capital raising purposes in connection with the closing of the Initial Business Combination (excluding any issuance of securities under the forward purchase agreement), at an issue price or effective issue price of less than $9.20 per share of Class A common stock (with such issue price or effective issue price to be determined in good faith by the Company's board of directors and, in the case of any such issuance to the Sponsor or its affiliates, without taking into account any Founder Shares held by the Sponsor or such affiliates, as applicable, prior to such issuance (the "Newly Issued Price")), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for funding the Initial Business Combination, and (z) the volume weighted average trading price of the Class A common stock during the 20 trading day period starting on the trading day prior to the day on which the Company consummates the Initial Business Combination (the "Market Value") is below $9.20 per share, the exercise price of the Warrants will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger price described above will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price. Additionally, in no event will the Company be required to net cash settle any Warrant. In the event that a registration statement is not effective for the exercised Warrants, the purchaser of a Unit containing such Warrant will have paid the full purchase price for the Unit solely for the share of Class A common stock underlying such Unit. There will be no redemption rights or liquidating distributions with respect to the Warrants, which will expire worthless if the Company fails to complete an Initial Business Combination within the 18-month time period.

[1]	Includes an aggregate of 750,000 shares that are subject to forfeiture to the extent the underwriter’s overallotment is not exercised in full (Note 4).

Fair Value Instruments (Details)	Sep. 30, 2020 USD ($)
Fair Value, Inputs, Level 1 [Member]
Fair Value Instruments (Textual)
Marketable securities	$ 176,777,682

Investment in Unconsolidated Joint Venture (Details) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	Sep. 30, 2020	Aug. 31, 2019
Investment in unconsolidated joint venture (Textual)
Financial commitment		$ 4,100,000
Ownership interest, percent		49.00%
Contributed amount	$ 1,561,000

Merger Agreement (Details) - USD ($)	Sep. 07, 2020	Jun. 04, 2019
Merger Agreement (Textual)
Cash	$ 110,000,000
Sponsor shares, description	Sponsor will enter into a letter agreement at the Closing, pursuant to which the Sponsor will agree to subject 1,718,000 of its shares in the Company (the “Sponsor Shares”), which formerly constituted shares of Class B common stock of the Company held by the Sponsor, to certain transfer and other restrictions, under which (a) 859,000 Sponsor Shares will be restricted from being transferred unless and until either, for a period of five years after the Closing, (i) the share price of the Company equals or exceeds $12.00 per share for any 20 trading days within any consecutive 30-trading day period or (ii) a change of control occurs for a share price of the Company equaling or exceeding $12.00 per share, and (b) the remaining 859,000 Sponsor Shares are subject to similar restrictions except that the threshold is increased from $12.00 to $16.00. If after the five-year period, there are no triggering events, the Sponsor Shares will be forfeited and canceled for no consideration. If after the five-year period, only the triggering event described in clause (a) above has occurred, the remaining 859,000 Sponsor Shares described in clause (b) will be forfeited and canceled for no consideration.
Common stock shares issued		10,000
Aggregate consideration	$ 300,000,000
Sale of shares	30,000,000
Additional shares issued	200,000
Equity Commitment Letter [Member]
Merger Agreement (Textual)
Forward purchase agreement, description	The Equity Commitment Letter effectively terminated the forward purchase agreement entered at the time of the Public Offering requiring the Sponsor and its affiliate to purchase immediately prior to the closing of the Business Combination an aggregate of 2,500,000 units, each comprised of one share of Class A common stock and one-half of one warrant.
Common stock shares issued	4,000,000
Aggregate share value	$ 40,000,000
Share price	$ 10.00

Commitments and Contingencies (Details) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Operating
Remainder of 2020	$ 167,000	$ 614,000
2021	685,000	685,000
2022	755,000	755,000
2023	825,000	825,000
2024	895,000	895,000
Later years	1,644,000	1,644,000
Total minimum lease payments	4,971,000	5,418,000
Capital
Remainder of 2020	4,000	13,000
2021	15,000	13,000
2022	6,000	4,000
2023
2024
Later years
Total minimum lease payments	25,000	30,000
Less amounts representing interest	3,000	5,000
Present value of minimum lease payments	$ 22,000	$ 25,000

Commitments and Contingencies (Details Textual) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	1 Months Ended	9 Months Ended		12 Months Ended
	Jul. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Lease commitments Description		On June 24, 2016, Eos entered into a long-term non-cancelable, operating lease for 45,000 sq. ft. of space for its current headquarters facility in Edison, New Jersey. On April 26, 2017, Eos entered into a lease for an additional 18,000 sq. ft. of adjoining space. These leases expire in September 2026 with renewal options up to 2036. Further, these leases require monthly rent payments along with executory costs, which include real estate taxes, repairs, maintenance, and insurance. In addition, the terms of the leases contain cost escalations of approximately 10% annually. The Company also has certain non-cancelable capital lease agreements for office equipment.		On June 24, 2016, Eos entered into a long-term non-cancelable operating lease for 45,000 sq. ft. of space for its current headquarters facility in Edison, New Jersey. On April 26, 2017, Eos entered into a lease for an additional 18,000 sq. ft. of adjoining space. These leases expire in September 2026 with renewal options up to 2036. Further, these leases require monthly rent payments along with executory costs, which include real estate taxes, repairs, maintenance, and insurance. In addition, the terms of the leases contain cost escalations of approximately 10% annually. The Company also has certain non-cancelable capital lease agreements for office equipment.
Rent expense		$ 570,000	$ 570,000	$ 930,000	$ 1,007,000
Cost of goods sold		0	102,000	102,000	528,000
Research and development expenses		405,000	339,000	430,000	0
General and administrative expenses		165,000	129,000	$ 398,000	$ 479,000
Non cancellable purchase amount	$ 8,000,000
Vendor deposits		$ 3,143,000
Purchase commitment, description		The Company records a purchase commitment loss if the market selling price of Gen 2.3 Battery Systems sold to customers is less than the fixed cost to manufacture the product.
Loss on purchase commitments		$ 5,807,000	$ 0

Modification to the Terms of the Offering (Details)	1 Months Ended
Modification to the Terms of the Offering (Details)	May 19, 2020
Modification to the Terms of the Offering (Textual)
Modification, description	The size of the transaction was modified to 17,500,000 Units at an offering price of $10.00 per Unit. As a result, on May 19, 2020 the Sponsor returned 718,750 shares of Class B common stock to Company for cancellation. As a result of the modified terms and execution of the underwriting agreement on May 19, 2020 the financial statements have been modified to reflect the final terms of the agreement, see Note 1, Note 3, and Note 4.

Grant Expense, Net (Details) - EOS ENERGY STORAGE, LLC [Member] - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Grant Expense, Net (Textual)
Grant expense, gross	$ 7,000,000		$ 7,000,000
Grant expense, net	728,000	$ (526,000)	(469,000)	$ 1,418,000
Grant income	381,000	590,000	984,000	1,821,000
Grant costs	1,109,000	64,000	515,000	3,239,000
Grant receivable	286,000		326,000	678,000
Received payments	$ 4,743,000	$ 3,185,000	$ 3,209,000	$ 2,244,000

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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