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Heating (cell)

Verifies a fully charged cell soaked at elevated chamber temperature does not catch fire or explode. Two profiles: one for nickel-hydride cells, one for everything else.
Clause (method) 8.1.5
Clause (pass criteria) 5.1.4
Object cell
Status vs. 2020 revised (method only)
Observation period 1 h at test environment temperature

Pass criteria

A battery cell, after undergoing the heating test according to 8.1.5, should not catch fire or explode.

There is no insulation requirement and no leakage/housing-crack requirement at cell level. (PDF p. 11)

Source: GB 38031-2025, clause 5.1.4 (PDF p. 11).

Pre-conditions

  • Sample: A battery cell. (8.1.5.1)
  • Active protection: Any additional active protection circuits or devices on the cell are removed. (8.1.1)
  • Starting state: Cell standard-charged per clause 7.1.1. (8.1.5.2)
  • Chamber start temperature: Test environment temperature (22 °C ± 5 °C per 6.1.1). (8.1.5.3)

Test parameters

For cells other than nickel-hydride (Li-ion, etc.)

Parameter Value Source
Chamber ramp rate 5 °C/min 8.1.5.3
Target temperature 130 °C 8.1.5.3
Hold duration at target 30 min 8.1.5.3
Observation period 1 h at test environment temperature 8.1.5.4

For nickel-hydride cells

Parameter Value Source
Chamber ramp rate 5 °C/min 8.1.5.3
Target temperature 85 °C 8.1.5.3
Hold duration at target 2 h 8.1.5.3
Observation period 1 h at test environment temperature 8.1.5.4

Procedure

  1. Confirm the test object is a single battery cell with active protection devices removed. (8.1.1, 8.1.5.1)
  2. Standard-charge the cell using the method described in clause 7.1.1. (8.1.5.2)
  3. Place the cell in a temperature chamber initially at the test environment temperature. (8.1.5.3)
  4. Ramp the chamber temperature at 5 °C/min to the target temperature: 130 °C for cells other than nickel-hydride, or 85 °C for nickel-hydride cells. (8.1.5.3)
  5. Hold at the target temperature: 30 min for non-NiMH, or 2 h for NiMH. Then stop heating. (8.1.5.3)
  6. Observe the cell for 1 h at the test environment temperature. (8.1.5.4)
  7. Record any fire or explosion event during ramp, hold, or observation.

After-test observation

Observe the test object for 1 h at the test environment temperature. (8.1.5.4)

What changed from GB 38031-2020

  • The test method was revised vs. the 2020 edition (8.1.5). The pass criterion (5.1.4) was not listed in the preface change list, so the requirement itself is unchanged.
  • (Source: GB 38031-2025 preface, PDF p. 6.)

Migration impact: Cells previously certified under the 2020 method should be re-tested under the 2025 method ahead of the 2026-07-01 effective date for new type approvals.

Engineering notes (non-normative)

Engineering note (non-normative): The 5 °C/min ramp is the chamber air rate, not the cell-surface rate — large-format cells can lag the chamber by several minutes. Place a surface thermocouple on the cell and start the hold timer from when the cell surface reaches the target, otherwise small cells get a longer effective soak than large ones.

Engineering note (non-normative): The NiMH profile (85 °C / 2 h) is less aggressive in temperature but longer in duration than the Li-ion profile (130 °C / 30 min). Don't apply the Li-ion profile to a NiMH cell "for safety margin" — the test report must cite the specific profile per chemistry, and an over-temp NiMH result is not interchangeable with the standard's intent.