Thermal stability tests¶
Pack/system tests where the failure mode being verified is thermal — either an external fire impinging on the pack, or thermal runaway initiated inside the pack. Both live under clause 5.2.7 of GB 38031-2025 and both exclude nickel-hydride packs/systems.
| # | Clause | Test | Object | Pass | Status |
|---|---|---|---|---|---|
| 23 | 8.2.7.1 | External fire | pack / system | No explosion (fire allowed) | revised (both) |
| 24 | 8.2.7.2 / App. C | Thermal propagation ⭐ | pack / system / vehicle | No fire, no explosion + 5-min warning + smoke condition | revised (both) |
How they differ¶
| External fire | Thermal propagation | |
|---|---|---|
| Threat origin | Fire outside the pack (gasoline pool fire) | Thermal runaway inside a single cell |
| Pass bar | No explosion only | No fire, no explosion, 5-min warning, smoke safe |
| Insulation required after? | No | No |
| Observation | 2 h or until ext. T < 45 °C | Until all monitor points ≤ 60 °C, min 2 h |
| Vehicle-level option | No | Yes |
Why thermal propagation gets its own deep dive¶
Clause 5.2.7 b) plus Appendix C is the most consequential change in GB 38031-2025. It re-defines what passing looks like for an EV battery pack: a single-cell thermal runaway must not propagate to a pack-level fire or explosion. The pack-side procedure, the OEM documentation package, the trigger methods, and the runaway-confirmation rule are explained in the dedicated Thermal propagation deep dive.
Source: GB 38031-2025, clauses 5.2.7 (PDF p. 12) and 8.2.7 (PDF p. 23–24); Appendix C (PDF p. 26, 34–38).