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Overcharge (cell)

Verifies a fully charged cell driven 10 % above its termination voltage (or to 115 % SOC) does not catch fire or explode.
Clause (method) 8.1.3
Clause (pass criteria) 5.1.2
Object cell
Status vs. 2020 unchanged
Observation period 1 h at test environment temperature

Pass criteria

A battery cell, after undergoing the overcharge test according to 8.1.3, 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 5.1.2 (PDF p. 11).

Pre-conditions

  • Sample: A battery cell. (8.1.3.1)
  • 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. (8.1.3.2)

Test parameters

Parameter Value Source
Pre-test charge Standard charging per 7.1.1 8.1.3.2
Continued-charge current ≥ I3 (manufacturer-specified) 8.1.3.3
Stop condition 1.1 × the manufacturer's charging termination voltage OR 115 % SOC 8.1.3.3
Observation period 1 h at test environment temperature 8.1.3.4

Procedure

  1. Confirm the test object is a single battery cell with active protection devices removed. (8.1.1, 8.1.3.1)
  2. Standard-charge the cell using the method described in clause 7.1.1. (8.1.3.2)
  3. Continue charging at a current of at least I3 until the cell reaches 1.1× the manufacturer-specified charging termination voltage or 115 % SOC, then stop charging. (8.1.3.3)
  4. Observe the cell for 1 h at the test environment temperature (22 °C ± 5 °C, per 6.1.1). (8.1.3.4)
  5. Record any fire or explosion event during the overcharge or the observation window.

After-test observation

Observe the test object for 1 h at the test environment temperature. (8.1.3.4)

Engineering notes (non-normative)

Engineering note (non-normative): The "1.1× termination voltage or 115 % SOC" stop condition is OR'd, but in practice 115 % SOC is computed from the actual capacity recorded during pre-treatment (7.1.2). Pin one of the two as the controlling stop in the test plan and instrument it directly — chasing both during a runaway event is asking for a missed cutoff.

Engineering note (non-normative): Continuous-current overcharge at I3 (≈ C/3) is slow enough that the cell has time to vent before reaching the most aggressive thermal regimes. Expect off-gassing well before the stop condition; the test environment must be vented and remote-monitored.