Science & Tech · Gadgets & EVs · 3 hrs ago
Donut Lab battery module retained 93% of its energy at -22°F
A battery module from Finnish company Donut Lab retained about 93% of its energy after testing at -22°F (-30°C).
VTT tested a complete module containing 14 first-generation cells, comparing its output in the cold with its output at 77°F.
The module delivered 1,254 watt-hours in the cold, versus 1,354 watt-hours at room temperature, and kept about 97% of its charge capacity.
The test used no heating, insulation or other thermal management, and the module continued charging and discharging normally afterward.
Cold weather can reduce the usable energy of electric-vehicle batteries because low temperatures slow chemical reactions inside them.
The results come from one laboratory module, not a complete vehicle, so they do not show how much driving range an electric vehicle using this battery would retain.
Donut Lab says it is focusing on next-generation batteries and plans further system-level demonstrations.
A VTT test found that a Donut Lab battery module retained about 93 percent of its energy at -30°C (-22°F), without heating or insulation.
The 14-cell module delivered 1,254 watt-hours in the cold, compared with 1,354 watt-hours at 25°C (77°F).
It retained about 97 percent of its ampere-hour capacity, while its voltage fell further during cold discharge.
Donut Lab had previously claimed the battery could retain 99 percent of its capacity at -30°C.
The test covered one module in a laboratory and did not establish how much driving range an electric vehicle using the battery would retain.
- Who
- Donut Lab developed the battery module, and VTT conducted the test.
- What
- A 14-cell module retained about 93 percent of its energy at -30°C (-22°F) without heating or insulation.
- When
- The article was published on October 22, 2026; the test date is not stated.
- Where
- In a controlled test chamber; the chamber’s location is not stated.
- Why
- The test examined battery performance in extreme cold, a condition that can reduce the usable energy of electric-vehicle batteries.
This story does not have two clearly opposing sides.
VTT measured the module at 25°C (77°F), where it delivered 27.77 ampere-hours and 1,354 watt-hours.
Researchers kept the module at -30°C (-22°F) for five hours.
VTT repeated the discharge test, and the module delivered 26.8 ampere-hours and 1,254 watt-hours.
Donut Lab reported that the module continued charging and discharging normally, with no observed adverse effects.
- Cold test temperature
- -30°C (-22°F)
- Module size
- 14 first-generation Donut Battery cells
- Energy at -30°C
- 1,254 watt-hours
- Energy at 25°C
- 1,354 watt-hours
- Capacity retained
- About 97 percent of ampere-hour capacity
- Cold exposure
- Five hours
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