EVwire brief: Stellantis has integrated Factorial's FEST (Factorial Electrolyte System Technology) solid-state battery cells into a Dodge Charger Daytona development vehicle and launched a road-testing program to verify performance, safety, and reliability.
The milestone marks the first integration of solid-state cells into a Stellantis vehicle and, according to the companies, the first automotive integration of the technology in North America.
“Battery development is a balancing act. It's not enough to optimize a single metric. We need a system that delivers real benefits in a real vehicle. This milestone shows we are bringing solid-state batteries closer to our customers with the potential for longer range, faster charging and lower costs.”

The STLA Large-based Charger Daytona is the first vehicle in the multi-stage demonstration program
The testing program now underway will tune and verify pack performance and reliability under real-world charging and driving conditions, along with vehicle safety. The Charger Daytona is the first vehicle in the companies' previously announced multi-stage development vehicle program. Factorial CEO Siyu Huang shared a comment about the project.
“We are deeply honored to work alongside Stellantis, one of the world's great mass-market automakers, on this STLA Large-based development car. What we have built together, from cell chemistry to pack architecture to enable real-world road testing, is exactly the kind of deep, full-stack collaboration that solid-state has always required.”
The road testing builds on cell-level validation from 2025, when Stellantis and Factorial demonstrated FEST cells with an energy density of 375 Wh/kg, charging from 15% to 90% in just 18 minutes, and reliable operation from -30°C to 45°C (-22°F to 113°F).

The STLA Large-based Charger Daytona is equipped with solid-state battery modules
Context:
Getting Factorial’s solid-state cells into an actual car required new engineering. The solid-state cells were integrated into the existing battery pack using a patented mechanical architecture designed by Stellantis, with control systems and pack design adapted to bring out the cells' performance while meeting automotive safety and durability requirements.
Factorial counts Mercedes-Benz, Stellantis, Hyundai, and Kia among its automaker backers, along with IQT, the strategic investor for the US national security community. Mercedes-Benz has already taken Factorial's cells on the road too, with a lightly modified test vehicle achieving over 1,200 km (about 745 miles) of range on a single charge.
Source: Stellantis press release
DIG DEEPER into Batterywire for the latest battery technology news, and join 14,000+ EV geeks reading EVwire.




