Stellantis Idles French EV Plants as Battery Venture ACC Fails to Keep Pace

Stellantis will temporarily halt vehicle assembly at its Sochaux and Rennes plants in France in late October 2026 because its battery joint venture, Automotive Cells Company (ACC), is still unable to deliver enough long-range electric vehicle batteries. The carmaker informed staff representatives at works council meetings held on September 29, 2026, and confirmed the schedule in a press statement the same day.

Under the plan, the Sochaux plant in eastern France, historic home of the Peugeot brand and producer of the Peugeot 3008 and 5008, will stop from October 23 to October 30. The Rennes La Janais plant in Brittany, which builds the Citroen C5 Aircross, will stop from October 22 to October 30. Production at both sites is expected to restart at the beginning of November. Stellantis explained that the availability of certain batteries used in the long-range versions of its electric models is insufficient, while demand for these versions remains strong, especially from business and fleet customers. The Citroen C5 Aircross is particularly exposed because its long-range electric version is currently being rolled out in several markets.

Two other French sites will also pause in October, but for reasons unrelated to batteries. Mulhouse will be idle from October 15 to October 30 because of weaker than expected demand for models such as the Peugeot 308, and Poissy will stop from October 19 to October 23 to keep dealer inventories under control. Stellantis said the overall adjustment aims to avoid building up stocks of vehicles that do not match what customers are actually ordering.

The bottleneck sits at the ACC gigafactory in Billy-Berclau and Douvrin, in the Hauts-de-France region. ACC is owned by Stellantis, Mercedes-Benz and TotalEnergies, and this French site is currently its only mass production plant. Its first production block, inaugurated in May 2023, has a nominal annual capacity of 13 GWh, with a long-term target of 40 GWh at the site by 2030. Stellantis is both the largest shareholder of ACC and, so far, its only customer. The cells go into electric models built on the STLA Medium platform, such as the Peugeot e-3008 and e-5008, the Opel Grandland Electric and the DS N°8. Stellantis stated that it currently depends on ACC for its long-range batteries and cannot replace them with packs from another supplier.

The supply problem is not new. The ramp-up of the Douvrin factory has run behind schedule since 2025. In November 2025, Italian financial media reported scrap rates of 15 to 20 percent on the production lines and costs well above those of Asian competitors, and French press reports indicate that ACC reached only about half of its 2025 production targets. In early February 2026, reports revealed that ACC could equip only around 1,000 Stellantis vehicles per month with long-range batteries, far below plan, and that buyers of these versions faced delivery delays of up to eight months. ACC admitted at the time that the ramp-up was proving difficult.

These difficulties also reshaped the European strategy of the joint venture. In February 2026, ACC confirmed that its planned gigafactories in Kaiserslautern, Germany, and Termoli, Italy, which had been on hold since May 2024, were definitively shelved. The company said the ramp-up in France was taking longer and costing more than expected and was weakening its financial position, and that building new plants in that context would be irresponsible. To lift output, ACC reportedly brought in a team of experts from China to help reduce defect rates.

The shortage persisted through the spring and summer. In April 2026, German trade press reported that private buyers of long-range Opel Grandland, Peugeot e-3008 and e-5008 models were being told to expect deliveries in the first or second quarter of 2027, while some dealers could no longer obtain firm delivery dates at all. The long-range variants use a 97 kWh battery instead of a 73 kWh pack and cost close to 5,000 euros more than the standard versions, so the delays hit some of the most valuable electric trims in the Stellantis range.

By the end of September 2026, ACC had reportedly cut its defect rates and stabilized its production, and Stellantis acknowledged that the battery maker had made major progress. The carmaker nevertheless said the volumes it receives are still not sufficient. At the same time, a recent jump in fuel prices has boosted demand for electric cars in France, which widens the gap between incoming orders and the number of long-range batteries available.

The October stoppages will place employees at Sochaux and Rennes on temporary short-time work for about one week. The Rennes La Janais site alone employs around 2,200 people. Whether further stoppages follow in the coming months will depend on how quickly ACC can raise its output, including the start of its second production block at Douvrin, which had been scheduled for mid-2026.

The situation shows how dependent European carmakers remain on a very small number of local battery cell plants, and how a single underperforming gigafactory can hold back vehicle assembly and electric vehicle deliveries across an entire group.