Donut Lab battery keeps 93% energy at -30°C without heating

Finnish company Donut Lab and VTT tested a 14-cell Donut Battery module: at -30°C it delivered 1,254 Wh versus 1,354 Wh at 25°C, retaining 97% of charge capacity. The module had no heaters, insulation or thermal management.

• 48V module delivered 1,254 Wh at -30°C and 1,354 Wh at 25°C
• 97% of ampere-hour capacity retained, but 93% of energy due to voltage drop
• VTT tested a full 14-cell module with no thermal management
• Donut Lab had earlier claimed 99% capacity retention at -30°C