Skip to content

External short-circuit protection

Verifies the battery system's protection devices interrupt or sustain a low-resistance external short across the high-voltage terminals without losing electrical safety.
Clause (method) 8.2.13
Clause (pass criteria) 5.2.13
Object system
Status vs. 2020 revised (requirements)
Observation period 1 h at test environment temperature

Pass criteria

After the external short-circuit protection test, the battery 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 5.2.13 (PDF p. 12).

Pre-conditions

  • Object: The test object is a battery system. (8.2.13.1)
  • Ambient temperature: 20 °C ± 10 °C (or higher if specified by manufacturer). (8.2.13.2 a)
  • Protection devices: All protection devices that affect the functionality of the test object and are related to the test results shall be in normal operation at the start. (8.2.13.2 b)
  • Contactors: Main contactors used for charging and discharging shall be closed at start (representing operable / external-charging-allowed mode). (8.2.13.3 a)
  • 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
Ambient temperature 20 °C ± 10 °C (or higher per manufacturer) 8.2.13.2 a)
External short-circuit resistance ≤ 5 mΩ 8.2.13.3 b)
Connection Positive ↔ negative terminals shorted together 8.2.13.3 b)
Maintain short until (a) Protection trips, or (b) Housing T stable (ΔT < 4 °C over 2 h) then continue short for ≥ 1 h more 8.2.13.4
Multiple trials allowed Yes — if test cannot complete in a single trial 8.2.13.3 a)
Post-test observation 1 h at test environment temperature 8.2.13.5

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. Bring ambient to 20 °C ± 10 °C (or higher per manufacturer). (8.2.13.2 a)
  4. Confirm all relevant protection devices are in normal operation. (8.2.13.2 b)
  5. Close the main contactors used for charging and discharging. (8.2.13.3 a)
  6. Connect the positive and negative terminals together with a short-circuit path of resistance ≤ 5 mΩ. (8.2.13.3 b)
  7. Maintain the short until either: a. The protection function activates and terminates the short-circuit current, or b. The housing temperature stabilizes (ΔT < 4 °C over 2 h), then continue the short for at least 1 hour more. (8.2.13.4)
  8. If the test cannot be completed in one trial, conduct two or more trials. (8.2.13.3 a)
  9. Open the short and observe the test object at the test environment temperature for 1 hour. (8.2.13.5)
  10. Re-measure insulation per Appendix B; inspect for leakage, housing cracks; confirm no fire/explosion.

After-test observation

Observe the test object for 1 hour at the test environment temperature (22 °C ± 5 °C) after the short is opened. (8.2.13.5)

What changed from GB 38031-2020

  • Listed in the preface change list as requirements revised (5.2.13). The test method (8.2.13) is not flagged in the preface as 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): The "tripped or temperature-stable + 1 h more" termination is the headline mechanic. A pyrofuse that opens immediately gives the easiest pass; a system that relies on relay opening also passes if the contactor logic responds. A pack with no protection must instead survive the steady-state short until housing temperature stabilizes plus a one-hour soak — that is a much higher bar and effectively requires the cell-level chemistry plus interconnect impedance to limit current to a sustainable level.

Engineering note (non-normative): The 5 mΩ external-short value is the same value used in the cell-level external-short test (8.1.4). At system-level voltages the corresponding short-circuit currents are very large; specify the bus-bar and load contactor on the test rig accordingly. Multi-trial provision exists because a single trial may consume a fuse or contactor before the test articles are exercised — plan for two trials by default.