technology•Sat, October 24, 2026•4 min read

Donut Lab’s New EV Battery Defies Freezing Temps in Latest Test

Finnish startup Donut Lab has successfully put its first-generation battery cells through extreme cold-weather testing. The results show the module retaining 93% of its energy at -30°C, offering a potential solution to one of the biggest challenges facing modern electric vehicles.

Solving the Winter Range Problem

For many electric vehicle owners, winter is the 'moment of truth'—a season where driving range often plummets as sub-zero temperatures sap battery efficiency. Finnish startup Donut Lab is looking to change that narrative. Following a series of rigorous evaluations conducted by the VTT Technical Research Centre of Finland, the company’s first-generation battery cells have demonstrated remarkable performance in deep-freeze conditions.

A 14-cell module underwent intense testing at -30°C.

The Results: How It Performed

VTT tested a complete module containing 14 of Donut Lab’s first-generation cells without the use of external heating or insulation. Under these harsh conditions, the results were striking:

Capacity Retention: The module retained 97% of its initial ampere-hour capacity.
Energy Output: It delivered 1,254 watt-hours at -30°C (-22°F), compared to 1,354 watt-hours at a baseline of 25°C (77°F).
Efficiency: This equates to roughly 93% energy retention, even without thermal management systems.

Donut Lab noted that in a real-world vehicle application, the battery would typically be housed in an insulated case, which would likely further enhance performance by trapping the heat generated by the battery during discharge.

Winter is the moment of truth for every battery. All electric vehicle owners know what happens to driving range when the temperature drops.
— Marko Lehtimäki, CEO of Donut Lab

A Broad Testing Roadmap

This cold-weather test marks the conclusion of a comprehensive evaluation program for Donut Lab's Gen1 cells. VTT has put the technology through a gauntlet of trials to ensure durability and reliability, including:

Five-minute fast-charging capabilities.
High-temperature performance testing up to 100°C (212°F).
Assessment of swelling and internal pressure.
Self-discharge rates and energy density.

Looking Toward the Future

With the Gen1 testing phase wrapped up, Donut Lab is shifting its focus toward next-generation iterations. The company plans to move forward with system-level demonstrations, aiming to prove that their technology can handle the rigors of the road beyond the laboratory setting. For an industry searching for ways to minimize the impact of climate on EV range, the data suggests Donut Lab is a name worth watching.

Key Takeaways

Donut Lab’s Gen1 battery cells retained 93% of their energy capacity at -30°C.
The tests were conducted by the independent VTT Technical Research Centre of Finland.
No external heating or insulation was used during the testing process, showing the inherent resilience of the cell design.
The evaluation was part of a broader testing program covering fast-charging, heat resistance, and structural integrity.
The company is now transitioning from Gen1 evaluation to next-generation battery development and system-level demonstrations.

FAQ

Does the Donut Lab battery require external heating in the cold?

No. The VTT test showed that the module retained 93% of its energy at -30°C without any external heating or insulation.

What is the significance of the VTT testing?

VTT is an independent technical research center. Their involvement provides verified data on the company's performance claims regarding cold-weather efficiency.

How did the battery perform compared to room temperature?

The module produced 1,254 watt-hours at -30°C, compared to 1,354 watt-hours at 25°C, resulting in approximately 93% retention of energy output.

What happens to the battery after testing?

According to the reports, the battery module continued to charge and discharge normally after the cold-weather tests with no adverse effects observed.