Donut Lab Episode 17: The Winter Test
Donut Lab is back with another test of its much-discussed solid-state battery. This time, it's been put through its paces at -30°C, with another independent test from Finland's VTT Technical Research Centre. The latest instalment of I Donut Believe gives us more numbers to chew over. And, as ever with Donut Lab, there's a bigger question hanging over the results.
For more Donut Lab news, visit our Donut Lab page.
Donut Lab Puts its Battery in the Deep Freeze
This time, it wasn't a single cell being tested. VTT tested a complete battery module, measuring its performance at 25°C before dropping the temperature to -30°C and discharging it at 1C.
The module used 14 Donut Battery V1 cells connected in series, plus a battery management system. There was apparently no heating, cooling or insulation to help it out.
At room temperature, the module delivered 27.77 amp-hours (Ah) and 1,353.9 watt-hours (Wh). At -30°C, those figures fell to 26.821 Ah and 1,253.9 Wh. That means the module retained approximately 97% of its amp-hour capacity, while its energy output fell to around 93% of the room-temperature result.
There's a difference between those two figures. Amp-hours measure electrical charge, while watt-hours tell us how much energy the battery actually delivered. The module held on to 97% of its charge capacity, but the drop in voltage appears to be the main culprit behind the lower energy output.
VTT also monitored the temperatures inside and outside the module. During the test, the internal temperature climbed to around 38°C, while the outer surface reached approximately -6°C. Afterwards, the module could still be charged and discharged normally, with no observable changes detected.
Donut Lab says the results back up its cold-weather claims. It previously estimated the battery would retain 99% of its capacity at -30°C. The actual result came in a little lower, but 97% is still pretty close to the company's estimate.
For the full VTT test report, visit, VTT - Customer Report
The BCB Take
Fair play to Donut Lab for putting more test data out there. Independent results give us something concrete to look at, rather than another set of impressive claims in a presentation. This is useful information, and we'd like to see more of it.
But here's the rub. When Donut Lab unveiled the battery at CES in January, the message was that it was ready for production, with Verge Motorcycles expected to bring it to the road in the first quarter of 2026. We're now in October. We've had more tests, more figures and more claims, but where are the bikes?
Meanwhile, the rest of the battery industry hasn't been sitting around waiting. Semi-solid-state batteries are already powering some Chinese electric cars, although they're not the same as fully solid-state technology. Progress is happening, and Donut Lab won't have the first-mover argument to itself forever. The longer riders wait for a production bike, the more important it becomes to show what makes this battery different.
Keep the test results coming, Donut Lab. But it's time to show us the bikes.
Ride safe, folks.
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