Donut Labs Drops High Temperature Performance Report [pdf]

The Battery & Test Setup

   - Cell tested: Donut Lab "Solid-State Battery V1" – a pouch cell labeled DL2
   - Nominal specs: 26 Ah capacity, 3.6V nominal voltage, 94 Wh energy
   - Tested by: Independent third-party lab (VTT) at customer request
   - Test equipment: PEC ACT0550 cell tester + Weiss climate chamber capable of -40°C to +180°C

   - Actual capacity measured: 24.9 Ah (slightly below 26 Ah nominal, but within reasonable variance)
    - +80°C discharge: Delivered 110.5% of room-temperature capacity (27.48 Ah vs 24.87 Ah at 24A)
    - +100°C discharge: Delivered 107.1% of room-temperature capacity (27.61 Ah at 12A)
    - Energy efficiency: ~89-90% round-trip efficiency observed
    - Charging: All charging performed at +20°C for safety; cell accepted charge normally after both high-temp tests

    Cell used a 2.4kg steel plate on top for mechanical pressure during testing
    Post-100°C test: Cell pouch lost vacuum (visible inflation/deflation) but remained electrically functional
    No visible damage after 80°C test; cell appeared physically intact after 100°C test despite vacuum loss

    Energy density: No weight and volume was mentioned

    Cycle life: VTT ran only 3 test cycles total.

    Cost Claims: Nothing about cost is mentioned

    Material Claims: No chemical analysis or materials analysis.

    No abuse testing: No nail penetration, no overcharge, no short-circuit, no crush tests.