Fair enough. Here you go.
Shop the MerchThird Party Testing
This website serves as the platform for publishing validation results and technical documentation related to the Donut Solid State Battery. Donut Lab has commissioned the internationally renowned VTT Technical Research Centre of Finland to conduct independent measurements of the battery’s performance and key characteristics. Unless otherwise stated, all tests presented here have been conducted by VTT. Full reports will be published alongside detailed video documentation that walks through the procedures, showcases the test setups, and explains the results.
Introducing “I Donut Believe”
Donut Lab has commissioned internationally respected VTT Technical Research Centre of Finland to independently measure the performance and characteristics of its solid-state battery. Through third-party testing under controlled research conditions, Donut Lab provides verified data to support its performance claims. In the video, CEO Marko Lehtimäki explains the company’s perspective and the rationale for launching the series and publishing the results in this format.
Watch the launch video
Fast Charge Performance Test
The first independent test of the Donut Solid State Battery, conducted by VTT Technical Research Centre of Finland, evaluates its charge performance under demanding conditions without active cooling. The cell was tested at both 5C and extreme 11C charge rates, confirming previously stated fast-charging targets, including a 0–80% charge in just 4.5 minutes at 11C. The results demonstrate exceptional charging capability alongside stable thermal behavior, providing verification of the battery’s high-power performance.
Watch the video Download full VTT test report
High Temp Performance Test
The 2nd independent test of the Donut Solid State Battery, conducted by VTT, evaluates its capacity and operational stability under sustained high-temperature conditions. At 80°C, the battery delivered 110% of its nominal room-temperature capacity with improved efficiency due to reduced internal resistance. After multiple hours at 100°C, it maintained approximately 107% capacity and recharged to full without degradation, confirming stable performance in environments exceeding the safe operating limits of conventional Li-ion batteries.
Watch the video Download full VTT test report
Self-Discharge Test
The 3rd independent test of the Donut Battery, conducted by VTT, evaluates its charge retention over an extended idle period. The cell was connected to a battery tester for ten days, with voltage measured every 10 seconds. Cell voltage stabilised within the first 10 hours and remained level for the remaining nine and a half days, confirming normal battery-type charge retention – not the rapid linear discharge characteristic of supercapacitors. The results demonstrate stable, predictable energy storage suitable for real-world vehicle applications.
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Verge Motorcycles
Sneak Peek: Fast Charging Solid-State Battery Pack
Unlike the previous instalments, this test was not conducted by VTT. It was captured at a public charging station during a system validation session with our customer Verge Motorcycles. A previous-generation mule bike equipped with a Donut solid-state battery pack demonstrated pack-level 5C fast charging on the standard range variant — an 18 kWh (nominal capacity), fully air-cooled design. Three times faster charging than the previous model year, and the fastest of any production electric motorcycle.
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Safety Demonstration Test
The 4th independent test of the Donut Battery, conducted by VTT, evaluates the cell’s ability to operate safely after sustaining damage. During our previous high-temperature test, the pouch surrounding the cell lost its vacuum — a failure that would cause fire or thermal runaway in any conventional lithium-ion battery. We took that same damaged cell and cycled it through five 1C cycles and 50 fast-charge cycles at 5C. No temperature spikes, no fire risk. In this scenario the Donut Battery fails gracefully when damaged, continuing to operate safely at reduced capacity rather than posing danger to the user.
Watch the video Download full VTT test report
The April 1st Interview
On this special day, we sat down with Donut Lab CEO Marko Lehtimäki to go deeper on the “I Donut Believe” series and he decided to share some secrets.
Some of what you’ll hear in this interview has never been shared publicly before. Whether you believe it… well, that’s up to you.
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Deep Dive: Inside the TS Pro Battery Pack
Going from a single cell to a full battery pack is where solid-state technology gets real. This video is a celebration of what Verge has achieved and a deep dive into how the solid-state battery pack is built – the architecture, the specs, the cooling, the charging – explaining why this is one of the simplest battery pack designs in the industry while delivering the fastest charging of any production motorcycle.
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Swappable Solid-State Battery Demonstration
How can Donut Battery transform existing vehicles? In this episode, we built a swappable battery demonstrator to test exactly that. The result is a smaller, lighter pack with more capacity, faster charging, and simplified design. Even with this simple demonstrator, you can already start to see how much solid-state batteries could change everyday use cases like last-mile delivery, where range, uptime, and charging speed directly define how much work a vehicle can do in a day.
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Swelling Test
Solid-state cells usually swell up to 20% during cycling, forcing pack engineers to build elaborate clamping systems that erase the cell-level gains. This independent VTT test evaluates the Donut Battery’s swelling behaviour across charge and discharge cycles. A pre-aged cell was cycled at 0.5C, 1C, and 2C at ambient temperature. It breathed approximately 4.4% per cycle regardless of C-rate, roughly a fifth of the swelling typical of other solid-state cells. This means Donut Battery can be integrated into conventional pack designs without the specialised clamping systems solid-state chemistries usually require.
Watch the video Download full VTT test report