Donut Lab released two rounds of independent test results this week, and they tell a story that is both promising and incomplete. The Finnish startup's batteries can charge extraordinarily fast and withstand heat that would destroy conventional lithium-ion cells. Those claims now have hard data behind them. Everything else? Still waiting for proof.
The state-owned VTT Technical Research Centre of Finland confirmed that the cell charged from 0 to 80% in just 4.5 minutes at an 11C rate. For context, rapid charging at such rates would typically generate dangerous heat.At 80°C, the cell delivered 110.5% of its room-temperature capacity, and the company's original claim of stable operation at 80°C and 100°C has been validated.
Here's where fiscal reality bites.Donut Lab has marketed this battery as needing no active cooling, but at 11C charge rates, even passive thermal management with a single heat sink proved insufficient, and in a real vehicle, consistent 11C charging will require some thermal engineering. That gap between the marketing message and measured reality is exactly the kind of detail that separates genuine breakthroughs from overstated claims.
The bigger picture reveals what the company is not yet willing to prove.The VTT report addresses charging speed and charging speed only; the 400 Wh/kg energy density claim, which the chairman of Svolt's called physically impossible, remains completely untested by any independent party.Donut Lab's 100,000-cycle lifespan claim is orders of magnitude beyond anything demonstrated in the industry, and proving it through independent testing would take considerable time at any reasonable test rate.
There's a legitimate counterargument here.CEO Marko Lehtimäki argues that if the company had released full third-party validation immediately, the controversy would have simply shifted to questions about scalability, which takes months or years to provide irrefutable evidence for. Strategic disclosure of test results week by week keeps public attention focused on verified claims rather than moving goalposts. It is, from a business perspective, shrewd messaging.
Yet scepticism remains earned.A professor at the University of Maryland's Department of Materials Science and Engineering specialising in solid-state batteries said the insufficient data does not represent real-world usage in automotive applications, stating the data presented leaves a lot to be desired for many reasons.After the 100°C test, the battery's outer pouch lost its vacuum, which may indicate the cell lost its hermetic seal, the barrier that keeps outside air away from the sensitive internal chemistry.
The deadline looms.CEO Marko Lehtimäki staked his reputation on shipping Verge Motorcycles with these cells in Q1 2026—that deadline is now weeks away. When motorcycles roll off production lines and into customer hands, independent teardowns will answer questions no press release ever could. Until then, investors and customers are left with a technology that passes some tests brilliantly while leaving the most ambitious claims unproven. That is not inherently damning, but it is, by definition, incomplete.