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High altitude

Verifies the battery pack or system can stand and discharge at low atmospheric pressure (~4 000 m) without losing electrical safety — addresses operation, transport, and storage at altitude.
Clause (method) 8.2.10
Clause (pass criteria) 5.2.10
Object pack / system
Status vs. 2020 revised
Observation period 2 h at test environment temperature

Pass criteria

After the high-altitude test, the battery pack or system shall show no leakage, no housing crack, no fire, and no explosion. The insulation resistance after testing shall not be less than 100 Ω/V (DC), or 500 Ω/V if an AC circuit is present.

Source: GB 38031-2025, clause 5.2.10 (PDF p. 12).

Pre-conditions

  • Pre-treatment: Standard, per clause 7.2.
  • SOC: Highest working SOC per clause 6.1.10.
  • Insulation baseline: Measure before the test per Appendix B (clause 6.1.5).

Test parameters

Parameter Value Source
Atmospheric pressure 61.2 kPa (simulating altitude 4 000 m) 8.2.10.2
Temperature Test environment temperature (22 °C ± 5 °C) 8.2.10.2
Stand duration 5 h at low pressure 8.2.10.3
Discharge current ≥ I₃ as specified by manufacturer 8.2.10.4
Discharge endpoint Manufacturer-specified discharge-termination condition 8.2.10.4
Post-test observation 2 h at test environment temperature 8.2.10.5

Procedure

  1. Confirm pre-treatment per 7.2 and measure baseline insulation per Appendix B. (6.1.5)
  2. Adjust SOC to highest working value. (6.1.10)
  3. Place the test object in the altitude (low-pressure) chamber and reduce pressure to 61.2 kPa at the test environment temperature. (8.2.10.2)
  4. Maintain the low-pressure environment and let the test object stand for 5 hours. (8.2.10.3)
  5. While maintaining 61.2 kPa, discharge the test object at a current of at least I₃ until the manufacturer-specified discharge-termination condition is reached. (8.2.10.4)
  6. Restore atmospheric pressure and observe the test object at the test environment temperature for 2 hours. (8.2.10.5)
  7. Re-measure insulation resistance per Appendix B; inspect for leakage, housing cracks; confirm no fire/explosion.

After-test observation

Observe the test object for 2 hours at the test environment temperature (22 °C ± 5 °C) after the discharge step completes. (8.2.10.5)

What changed from GB 38031-2020

  • Listed in the preface change list as both requirements (5.2.10) and method (8.2.10) revised.

Migration impact: Already-type-approved vehicle models must comply from 2027-08-01. New type approvals from 2026-07-01. See Re-certification timeline.

Engineering notes (non-normative)

The notes below are practical interpretation, not part of the standard.

Engineering note (non-normative): 61.2 kPa is roughly the pressure at the Tibetan plateau driving altitude (4 000 m). The test catches two failure modes: pressure-driven seal leakage (housings designed sea-level-tight may bleed out gas), and arcing risk in low-density air at high-voltage interconnects. The discharge-while-low-pressure step exercises the second risk under load.

Engineering note (non-normative): "Discharge at ≥ I₃" means the manufacturer-defined 3-hour-rate current; check the manufacturer's I-rate definition before scheduling the chamber time. A pack at high SOC discharged at I₃ takes roughly 3 hours, putting total chamber time at ~8 hours (5 h stand + ~3 h discharge) plus pressure-down/up.