Ideal Power Inc美股招股说明书(2026-02-23版)

Table of Contents The information contained in this preliminary prospectus supplement and the accompanying prospectus is not complete and may bechanged. A registration statement relating to the securities has been declared effective by the Securities and Exchange Commission.This preliminary prospectus supplement and accompanying prospectus are not an offer to sell these securities and are not soliciting anoffer to buy these securities in any jurisdiction where the offer or sale is not permitted. SUBJECT TO COMPLETION, DATED FEBRUARY 23, 2026 PROSPECTUS SUPPLEMENT (to Prospectus dated January 9, 2026) Ideal Power Inc. Shares of Common Stock We are offeringshares of our common stock, par value $0.001 per share. In a concurrent private placement (the “Concurrent Placement”) pursuant to a securities purchase agreement with the purchasers in thisoffering, we are offering to each purchaser, with respect to the purchase of shares of common stock that would otherwise result in thepurchaser’s beneficial ownership exceeding 4.99% of our outstanding common stock immediately following the consummation of thisoffering, the opportunity to purchase pre-funded warrants. Each pre-funded warrant will be exercisable for one share of common stock at anexercise price of $0.001 per share. The purchase price of each pre-funded warrant in the Concurrent Placement will be equal to the price pershare of common stock in this offering, minus the exercise price of $0.001 per share. The pre-funded warrants will be immediately exercisableand may be exercised at any time until all of the pre-funded warrants are exercised in full. The pre-funded warrants and the shares of commonstock issuable upon exercise of the pre-funded warrants are not being registered under the Securities Act of 1933, as amended (the “SecuritiesAct”) and are not being offered pursuant to this prospectus supplement and the accompanying prospectus and are being offered pursuant to anexemption from the registration requirements of the Securities Act provided in Section 4(a)(2) of the Securities Act and Rule 506 ofRegulation D promulgated thereunder. The Concurrent Placement, if any pre-funded warrants are sold to purchasers in this offering, isexpected to close concurrently with this offering and on substantially the same terms and conditions as this offering. See “Concurrent PrivatePlacement” beginning on page S-13of this prospectus supplement for additional information with respect to the Concurrent Placement. Thisoffering is not conditioned on the closing of the Concurrent Placement and we cannot assure you that the Concurrent Placement will becompleted. Certain of our executive officers, directors and employees, including David Somo, our Chief Executive Officer and director, haveindicated an interest in purchasing shares of our common stock in this offering at the public offering price. However, indications of interest arenot binding agreements or commitments to purchase and such persons may determine to not purchase any shares in this offering. In addition,the underwriters could determine to sell fewer shares to such persons than they have indicated an interest in purchasing or could determine notto sell any shares to such persons. Our common stock is listed on The Nasdaq Capital Market (“Nasdaq”) under the symbol “IPWR.” On February 20, 2026, the lastreported sale price of our common stock on Nasdaq was $3.57 per share. As of February 20, 2026, the aggregate market value of our outstanding common stock held by non-affiliates, or public float, wasapproximately $43.8 million, based on the closing price of our common stock as reported on Nasdaq on February 2, 2026, as calculated inaccordance with General Instruction I.B.6 of Form S-3. Table of Contents Investing in our securities involves risks. See“Risk Factors”on pageS-5of this prospectus supplement, on page4 of theaccompanying prospectus and in the documents which are incorporated by reference herein and therein. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation tothe contrary is a criminal offense. (1)See “Underwriting”for a description of the compensation payable to the underwriter. Delivery of the securities is expected to be made on or about February, 2026. We have granted the underwriter an option for a periodof 30 days to purchase an additionalshares of our common stock to cover over-allotments, if any, of the shares of common stock offered bythis prospectus supplement and the accompanying prospectus. The purchase price to be paid by the underwriter per additional share ofcommon stock will be $, less the underwriting discount. If the underwriter exercises the option in full, the total underwriting discountsand commissions payable by us will be $, and the total proceeds to us, before expenses, will