Finnish company Donut Lab has tested its first-generation battery module, demonstrating high performance in extreme cold. The tests, conducted by the VTT research center, confirmed that the system maintains efficiency without the need for heating or thermal management components.
During the experiment, the module, consisting of 14 cells, was kept at -30 C for five hours. At a discharge rate of 1C and a nominal voltage of 48 V, the battery retained approximately 93% of its initial energy, delivering 1254 Wh compared to 1354 Wh at 25 C.
The capacity retention was even higher, with the module maintaining about 97% of its charge, dropping from 27.77 Ah to 26.8 Ah. The difference between energy and charge retention is attributed to voltage drop during cold discharge.
The testing process excluded any heating elements, cooling systems, or insulation. Sensors verified that the internal temperature of the module reached -30 C during the trial. This concludes the evaluation of the first-generation Donut Battery.
The company has previously tested these cells for fast charging, high-temperature performance up to 100 C, self-discharge, and energy density. Donut Lab is currently developing the next generation of traction batteries.
