GB 38031-2025 vs GB 38031-2020: engineering diff report

For BMS, battery pack, test-lab and homologation teams who need to know exactly what changed and what to prepare before 2026-07-01 (new approvals) and 2027-07-01 (existing approvals).

What's inside

1. Executive summary and transition timeline
2. New and changed definitions (battery subsystem, leakage, thermal event)
3. Full change map: 29 items from the foreword, with 2025 and 2020 clause numbers and an owner team
4. Deep dive: thermal propagation
5. Deep dive: bottom impact test
6. Deep dive: fast-charge cycling safety test
7. Other changed tests and same-type determination
8. Compliance checklist (also as Excel)
9. Sources

Free preview: bottom impact test (new in 2025)

Parameter	Value (8.2.16)
Impactor	Hemispherical, Ø30 mm, 10 kg, 45# steel
Direction	+z
Locations	3 underbody risk points chosen by the manufacturer (front, middle, rear), with technical justification
Energy	150 J ± 3 J
Observation	2 h
Pass (5.2.16)	No leakage, enclosure rupture, fire or explosion. Insulation ≥100 Ω/V (≥500 Ω/V with AC circuits)
Exemption	Packs on N-category vehicles with ≥200 mm ground clearance at full load

Why it matters: the manufacturer picks the 3 impact points, so the justification document becomes a compliance deliverable in its own right. The post-impact insulation check ties mechanical design (underbody shield, cooling plate) to HV insulation design. The full report covers how to choose and document the points.

Independent commentary, not a translation of the standard and not legal, certification or compliance advice. The official text published by SAMR/SAC prevails. The official free text: GB 38031-2025 on openstd.