SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements included herein have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Certain information and disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s Form 10-K filed with the SEC on February 28, 2022. In management’s opinion, these unaudited condensed consolidated financial statements have been prepared on the same basis as the annual financial statements and reflect all adjustments, which include normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2022 and the results of operations for the three months ended March 31, 2022 and 2021. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results to be expected for the full year ending December 31, 2022 or any other future interim or annual period. The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries.
Principles of Consolidation	All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Significant estimates, assumptions and judgments made by management include, among others, inventory valuation, the determination of the useful lives of property and equipment, fair value of preferred stock warrants, fair value of common stock warrants, fair value of contingent forward contracts liability, valuation of deferred income tax assets and uncertain tax positions, fair value of common stock and other assumptions used to measure stock-based compensation expense, and estimated incremental borrowing rates for assessing operating and financing lease liabilities. These estimates and assumptions are based on management’s best estimates and judgment. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, which management believes to be reasonable under the circumstances. The Company adjusts such estimates and assumptions when facts and circumstances dictate. Changes in those estimates resulting from continuing changes in the economic environment will be reflected in the financial statements in future periods.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with an original maturity at the date of purchase of three months or less to be cash equivalents. Restricted cash in other current assets and noncurrent assets is primarily related to letters of credit issued to the landlords for certain of the Company’s leasehold facilities.
Concentration of Credit Risk	Concentration of Credit RiskFinancial instruments that potentially subject the Company to concentration of credit risk consist of cash, cash equivalents, and accounts receivable. The Company places its cash primarily with domestic financial institutions that are federally insured within statutory limits, but at times its deposits may exceed federally insured limits. Further, accounts receivable primarily consists of current trade receivables from a single customer as of March 31, 2022 and December 31, 2021, which relates specifically to sales of its battery packs.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In November 2021, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance, which requires annual disclosures about transactions with a government that are accounted for by applying a grant or contribution accounting model by analogy. The disclosure requirements include information about the nature of the transactions and the related accounting policy, the line items on the balance sheet and income statement that are affected by the transactions, the amount applicable to each financial statement line and significant terms and conditions of the transactions. The guidance is effective for annual periods beginning after December 15, 2021 and can be applied either prospectively or retrospectively. The Company has adopted ASU 2021-10 prospectively on January 1, 2022. The adoption of this ASU did not have an impact to the consolidated financial statements and related disclosures.
Fair Value Measurement	The accounting standard for fair value measurements provides a framework for measuring fair value and requires expanded disclosures regarding fair value measurements. Fair value is defined as the price that would be received for an asset or the “exit price” that would be paid to transfer a liability in the principal or most advantageous market in an orderly transaction between independent market participants on the measurement date. The Company measures financial assets and liabilities at fair value at each reporting period using a fair value hierarchy, which requires the Company to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument classification within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. This hierarchy prioritizes the inputs into three broad levels as follows: •Level 1—Quoted prices (unadjusted) in active markets for identical assets or liabilities. •Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. •Level 3—Inputs that are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. Factors used to develop the estimated fair value are unobservable inputs that are not supported by market activity. The sensitivity of the fair value measurement to changes in unobservable inputs may result in a significantly higher or lower measurement.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

3 Months Ended

Mar. 31, 2022

Basis of Presentation and Principles of Consolidation

The accompanying unaudited condensed consolidated financial statements included herein have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Certain information and disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s Form 10-K filed with the SEC on February 28, 2022.

In management’s opinion, these unaudited condensed consolidated financial statements have been prepared on the same basis as the annual financial statements and reflect all adjustments, which include normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2022 and the results of operations for the three months ended March 31, 2022 and 2021. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results to be expected for the full year ending December 31, 2022 or any other future interim or annual period.

The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries.

Principles of Consolidation

All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Significant estimates, assumptions and judgments made by management include, among others, inventory valuation, the determination of the useful lives of property and equipment, fair value of preferred stock warrants, fair value of common stock warrants, fair value of contingent forward contracts liability, valuation of deferred income tax assets and uncertain tax positions, fair value of common stock and other assumptions used to measure stock-based compensation expense, and estimated incremental borrowing rates for assessing operating and financing lease liabilities. These estimates and assumptions are based on management’s best estimates and judgment. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, which management believes to be reasonable

under the circumstances. The Company adjusts such estimates and assumptions when facts and circumstances dictate. Changes in those estimates resulting from continuing changes in the economic environment will be reflected in the financial statements in future periods.

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments with an original maturity at the date of purchase of three months or less to be cash equivalents.

Restricted cash in other current assets and noncurrent assets is primarily related to letters of credit issued to the landlords for certain of the Company’s leasehold facilities.

Concentration of Credit Risk

Concentration of Credit RiskFinancial instruments that potentially subject the Company to concentration of credit risk consist of cash, cash equivalents, and accounts receivable. The Company places its cash primarily with domestic financial institutions that are federally insured within statutory limits, but at times its deposits may exceed federally insured limits. Further, accounts receivable primarily consists of current trade receivables from a single customer as of March 31, 2022 and December 31, 2021, which relates specifically to sales of its battery packs.

Recently Adopted Accounting Pronouncements

In November 2021, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance, which requires annual disclosures about transactions with a government that are accounted for by applying a grant or contribution accounting model by analogy. The disclosure requirements include information about the nature of the transactions and the related accounting policy, the line items on the balance sheet and income statement that are affected by the transactions, the amount applicable to each financial statement line and significant terms and conditions of the transactions. The guidance is effective for annual periods beginning after December 15, 2021 and can be applied either prospectively or retrospectively. The Company has adopted ASU 2021-10 prospectively on January 1, 2022. The adoption of this ASU did not have an impact to the consolidated financial statements and related disclosures.

Fair Value Measurement

The accounting standard for fair value measurements provides a framework for measuring fair value and requires expanded disclosures regarding fair value measurements. Fair value is defined as the price that would be received for an asset or the “exit price” that would be paid to transfer a liability in the principal or most advantageous market in an orderly transaction between independent market participants on the measurement date. The Company measures financial assets and liabilities at fair value at each reporting period using a fair value hierarchy, which requires the Company to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument classification within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. This hierarchy prioritizes the inputs into three broad levels as follows:

•Level 1—Quoted prices (unadjusted) in active markets for identical assets or liabilities.

•Level 2—Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

•Level 3—Inputs that are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. Factors used to develop the estimated fair value are unobservable inputs that are not

supported by market activity. The sensitivity of the fair value measurement to changes in unobservable inputs may result in a significantly higher or lower measurement.