Overview
- The third independent VTT report measured 97.7% charge retention after a 240-hour idle period on a single Donut Lab pouch cell.
- VTT recorded an initial 26.5 Ah discharge capacity; the self-discharge run charged the cell to ~50% (13.335 Ah) and recovered 13.029 Ah after rest.
- Voltage dropped 60 mV in the first 10 seconds and 103 mV in the first hour, then drifted only 12 mV from hour 10 to hour 240, indicating stabilization.
- Test engineers reported no visible damage or structural changes to the cell following the procedure.
- Earlier VTT reports confirmed 0–80% charging in about 4.5 minutes and high‑temperature discharge up to 100°C, while the headline claims of 400 Wh/kg and a 100,000‑cycle life remain unverified without cell mass and long‑term cycling data.