Stellantis has integrated Factorial’s FEST solid-state battery cells into a Dodge Charger Daytona development vehicle and has begun road testing, marking the first automotive integration of the technology in North America.
The integration builds on cell validation work completed in April 2025, when the companies demonstrated 77Ah FEST cells with an energy density of 375 Wh/kg and the ability to charge from 15 percent to over 90 percent in 18 minutes at room temperature. Those cells also operated reliably across a temperature range from -30 °C to 45 °C. Moving from those controlled lab conditions to a functioning vehicle required new mechanical architecture to accommodate the solid-state cells inside an existing battery pack, plus control-system adaptations to meet automotive safety and durability requirements.
Stellantis designed the patented mechanical architecture. Factorial supplied the cells. The road testing program now underway will calibrate pack performance and verify reliability under real charging and driving conditions.
Ned Curic, Stellantis Chief Engineering and Technology Officer, framed the milestone as proof that solid-state batteries are moving closer to production viability. He cited compatibility with existing lithium-ion manufacturing processes as a critical advantage for scaling the technology.
The development vehicle is based on Stellantis’ STLA Large platform, the same architecture that supports the production Dodge Charger Daytona. The companies announced a multi-stage development vehicle program previously; this is the first car in that program.
Mercedes-Benz has also tested Factorial’s solid-state cells. A modified EQS fitted with 106 Factorial cells traveled 745 miles on a single charge. Mercedes tested a production-adjacent configuration; Stellantis is testing a development pack in a current platform.
Factorial CEO Siyu Huang described the integration as full-stack collaboration, cell chemistry through pack architecture. The company has joint development agreements with Mercedes-Benz, Stellantis, Hyundai, and Kia. Stellantis invested $75 million in Factorial in 2021.
The partnership is moving from lab-validated cells to road-tested packs. Whether solid-state batteries deliver on the performance promises at a cost structure that works for mass-market vehicles is the question the road testing program exists to answer. Stellantis scheduled a demonstration fleet of Charger Daytona vehicles for 2026; the first car is now on the road.
Source: Stellantis. Images courtesy of Stellantis.
