Lithium iron phosphate module thermal runaway during full-charge test in Gansu
Apr 2023Published 31 Oct 2026Responsible editor: Chief Editor
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What happened
On 22 April 2023 at about 17:56, the Wuwei Fire and Rescue detachment received an alarm about a fire at a battery energy storage station in Minqin County, Wuwei, Gansu. The fire damaged one battery cabin, burned an area of about 30 square metres and caused direct economic losses of about 4.1 million yuan. There were no casualties. The station had four containerised battery cabins and a booster cabin. Around 15:00 that day, personnel were carrying out a full-charge test on cabins 1, 3 and 4 while equipment was being commissioned.
At about 17:30 a loud bang was heard, followed by white smoke with an irritating smell and then black smoke. Investigators found that module 12 in cluster 4 of cabin 1 had failed first, and the cells around it then went into thermal runaway. The fire service attributed the fire to thermal runaway of that lithium iron phosphate module.
Contributing factors
The fire service attributed the failure to operating errors during the full-charge test. The designed charging time for the affected module was 2 hours, but during the test it reached 3 hours. Overcharging changed the polarity behaviour of the lithium-ion cells, and exothermic reactions at the electrodes together with an internal short circuit caused by lithium dendrites led to thermal runaway. Station data showed that the battery management system issued a first-level over-voltage warning for the affected module before temperatures rose across the modules.
Lessons learned
- Treat full-charge and commissioning tests of battery storage as high-risk activities, and keep charge durations within the designed limits.
- Ensure battery management system limits are active and monitored during tests, not only in normal operation.
- When investigating a battery fire, use voltage, current and temperature logs to find the first module to fail, since a failing module typically drops to zero output first.
- Do not rely on the most heavily burned cell to locate the fault origin; combine X-ray, CT imaging and disassembly to confirm it.
- Brief all on-site test staff, including equipment manufacturer technicians, on thermal runaway warning signs and evacuation routes before energisation tests.
More lessons on design, standards and commissioning, detection and monitoring, investigation and fleet-wide checks, emergency response and public communication, from every incident on the register.
Source
Published 2026-10-31. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
