Donut Lab battery retains 97% capacity in -30°C cold test

Finnish technology company Donut Lab has released test results showing its battery module retains 97% of its ampere-hour capacity at -30°C (-22°F). The testing, conducted by the research organization VTT, evaluated a complete 14-cell module rather than an individual cell.

To simulate extreme conditions, the 48-volt module was placed in a temperature chamber without insulation, heating elements, or thermal management systems for five hours. While the module retained 97% of its capacity in terms of ampere-hours (26.8 Ah compared to a 25°C baseline of 27.77 Ah), the total energy delivered in watt-hours was approximately 93% of the baseline (1,254 Wh compared to 1,354 Wh). This reduction in energy output is attributed to the natural drop in battery voltage at extremely low temperatures.

The results aim to address a significant challenge for electric vehicle adoption, as cold weather typically reduces battery energy and charging performance. Donut Lab previously claimed a 99% capacity retention at these temperatures during CES 2026, though this latest independent test measured a slightly lower figure.