How WATTALPS Took an EIC Accelerator Battery From Diggers to Ships

Most lithium-ion batteries in electric machines are cooled by air or by liquid running through plates beside the cells. WATTALPS, a company in Moirans near Grenoble, drowns its cells instead: every cell and busbar sits in a dielectric fluid that does not conduct electricity. In May 2020 the European Innovation Council chose the company in the Green Deal round of the EIC Accelerator pilot, with blended finance, to turn that idea into a certified battery for electric construction machines. The project, WATTELSE, received an EU contribution of €1,650,950 towards a total cost of €2,358,500, according to CORDIS.

Six years later WATTALPS is still independent and still building batteries. It raised €11 million in a Series A in 2024, according to CEA-Liten and Powertrain International, and in 2026 it announced two type approvals and a battery supply role in a Codelco mining project. Its accounts show the cost: a net loss of €2,083,080 in 2025, the largest on record.

What WATTALPS Does Today

The company is active. The French register lists WATTALPS SAS as an operating company with its seat at 410 rue Aldo Eriani in Moirans, accounts for 2025 filed in June 2026 and no insolvency notice, according to the official company search and the BODACC gazette. Its website posted news on 13 October 2026.

WATTALPS sells modular lithium-ion battery systems from 48 V to 800 V and 10 kWh to 500 kWh, and has widened its market well beyond the construction sites WATTELSE was written for. Its customer stories name Vermeer, whose electric horizontal directional drill D20x22S3E uses WATTALPS batteries, the hydrogen truck retrofitter Hyliko, the 7-tonne hybrid work boat of the K-Challenge K3-H2 project, an unnamed port crane retrofit, and a development project with Doosan Bobcat in which a battery lets a compressor with a 22 kW motor run on an 11 kW grid connection. These are WATTALPS's own accounts, quoting engineers of the customers on its references page. No Vermeer, Hyliko or Doosan Bobcat announcement confirming the supply could be found for this article.

The one deal confirmed by a third party is in mining. On 11 June 2026 Codelco, the world's largest copper producer, signed a one-year agreement with CEA-Liten to study the electrification of underground mining equipment, co-financed by the French state through the FASEP fund. Codelco's press release and Mining Technology both say WattAlps will design and supply the batteries to be tested in Grenoble.

The Technology: Cells Bathed in Fluid

Heavy machines punish batteries. A drill or a crane draws short bursts of very high power, often in heat or frost, and cells that run hot age fast. WATTALPS immerses cylindrical cells, sourced mainly from Korea and Japan, in a fluid that it describes as non-toxic, biodegradable and non-flammable, and on demanding duty cycles circulates that fluid around each cell, according to its factory page and its marine approval notice. The claimed result is an even cell temperature, higher sustained power from a smaller pack and passive protection against a fire spreading from one failed cell to its neighbours. Its modules are also small, which lets one design be scaled to many machines, the point the WATTELSE proposal sold to makers of non-road mobile machinery.

The know-how came from the French research body CEA. Two of the three founders developed and patented the technology at CEA-Liten, according to CEA, and Desbois-Renaudin, who spent nine years at CEA, ran his first immersion-cooling project, for a large marine battery pack, in 2013, according to the company. The company's own pages disagree on the size of its patent portfolio: the factory page says seven patents protect the cooling technology, the home page says eight.

What WATTELSE Promised, and What CORDIS Shows

The European Commission's list of the 19 May 2020 Green Deal winners names WATTALPS of Moirans as the only company of the WATTELSE project, with blended finance, for "a versatile, modular lithium-ion battery system" able to keep heavy machinery running for an entire day at a high power rate. The grant agreement was signed on 9 November 2020 and the project ran from 1 November 2020 to 31 January 2023, according to CORDIS. CORDIS does not show whether that end date includes an extension.

The final periodic report sets out four goals and reports on each. CORDIS's results summary describes the project as taking the battery from a prototype at technology readiness level 6 to a validated product ready for mass production at level 8.

1. Prototype reaching the target specificationDeliveredA third-generation module for 800 V systems and an in-house battery management system to ISO 26262 were built; the report counts more than 120 pre-series modules. TECRIS assessed the ISO 26262 work, per Cyprus Shipping News.
2. Pre-series production processDeliveredA production line with quality and traceability controls in a three-building plant the report sizes at 6,500 modules a year on two shifts.
3. Full certification in EuropeDeliveredISO 9001 after an AFNOR audit in December 2022; tests to UN 38.3, IEC 62619 and ECE R100 Rev. 3. Kiwa certified IEC 62619, per Cyprus Shipping News.
4. Proofs of concept with user feedbackDeliveredA Yanmar Vio26 mini-excavator converted with CETIM to a 20 kWh battery and tested by end users; a worksite power bank built from second-life modules shown at Bauma.

On its own terms WATTELSE did what it set out to do by the time it closed in January 2023. What the report could not show is the commercial claim in the original objective: that machine makers would electrify with "a CAPEX divided by 20" and four times faster than with an in-house battery. No customer or third party has published such a comparison.

What Has Happened Since

The certification run continued after the project. In June 2025 WATTALPS ran nail-penetration tests on a fully charged module, witnessed by Bureau Veritas, and reports that thermal runaway stayed in the targeted cell, with no fire, in three tests, according to its test report. In January 2026 it announced Marine Type Approval from Bureau Veritas and said its 39 kWh, 280 kW system was the first in the world type-approved under UN R100 Revision 5 by Germany's Federal Motor Transport Authority (KBA), for heavy buses and trucks. Neither Bureau Veritas nor KBA publications confirming these approvals could be found for this article; the "world first" claim could not be verified. In February 2026 the company received the Euromaritime award for safety and security at sea, by its own account.

The money came in 2024. The €11 million Series A was led by new investors Supernova Invest, Move Energy and Ring Capital, with CASRA Capital and the existing shareholders EIT InnoEnergy, Eximium and the EIC Fund, according to InnoEnergy and Silicon Canals. Both reported that revenue had grown about fivefold in 2023 and more than tripled in 2024, without giving a figure, and that WATTALPS planned to double its team to 40 within 18 months and pass 100 staff by 2028. The register records capital increases in May, July and September 2024 and again in May 2025, according to BODACC; no 2025 funding round has been announced.

The Money

WATTALPS files its income statement under the confidentiality option open to small French companies, so its turnover is not public. The net results are. The INPI ratios dataset shows losses of €661,046 in 2022, €464,614 in 2023, €1,138,726 in 2024 and €2,083,080 in 2025, the last figure matching the official company search. The same dataset puts equity at 52% of the balance sheet at the end of 2025, down from 74% a year earlier, which fits a company spending its Series A.

The growth plan is harder to check. In 2024 WATTALPS said its Moirans plant made about 2,000 batteries a year and that it would multiply capacity by eight and pass €100 million in turnover within five years, according to Powertrain International. The year before, the target had been €66 million in five years, according to the CORDIS results summary, which also gave the plant's capacity as up to 50 MWh a year. The company's factory page still gives that 50 MWh figure today, and no expansion of the plant has been announced. Staff were in the 10 to 19 band in 2024, according to INSEE data in the official company search; whether the team reached 40 could not be verified.

Why It Matters for Europe

Batteries are one of the industries the EU has tried hardest to keep at home. The European Battery Alliance, launched in 2017, aims to build a "competitive, circular, sustainable and safe value chain" in Europe, and the Net-Zero Industry Act lists battery and storage technologies among those whose European manufacturing should meet at least 40% of the EU's annual needs by 2030. WATTALPS does not make cells, which it buys mainly from Korea and Japan; it designs and assembles packs in France, with 95% of the remaining components from European suppliers, by its own account. Its niche, the electrification of diggers, drills, cranes, mining vehicles and boats, is still small: only 0.1% of the installed base of industrial and agricultural machines ran on electricity in 2024, according to CEA-Liten.

The Verdict

WATTALPS has not been asked for comment for this article. It is based entirely on public records, company statements and EU project data, linked throughout.