At 6:20 p.m., a fire broke out in a 14 m² thermal testing cell at an industrial test centre. A short-circuit test on a lithium-ion battery had been started in the cell at 2:30 p.m. and ended at 3:30 p.m. During the test, the temperature rose to 400 °C. At 5:00 p.m., the temperature dropped to below 50 °C. The test protocol calls for a number of parameters (temperature, voltage, and gas content) to be continuously monitored and measured for 24 hours. A video recording of the events in the cell made it possible to determine the timeline. The battery went into thermal runaway at 6:07 p.m. The fire started at 6:20 p.m. and the automatic fire alarm went off at 6:45 p.m. The internal emergency plan was implemented. The operator cut off the centre’s power supplies. Firefighters extinguished the fire. The box of batteries was removed to the open air. The room was ventilated.

The fire caused significant material damage. The inside of the thermal cell was burnt to a cinder, its front was cracked, the gas analysers and sprinkler system were out of commission, and the cell’s instrumentation system was destroyed. The gas scrubber, extraction ducts, and hoist above the cell had to be inspected.

The thermal runaway occurred 2½ hours after the test ended. However, the temperature 1½ hours after the test’s end was below 50 °C. This had never been recorded before. The operator is working to determine the causes of this delayed thermal runaway.

An internal emergency response unit was set up on 24 July to manage the post-accident situation. Several areas for improvement were identified following feedback given on 27 July:

• redefine the maximum dimensioning of the tests;
• consider retrofitting the cell (customise automatic fire suppression system, etc.);
• consider a remote connection for accessing the cameras inside the cell;
• overhaul the test procedures.

An electric battery had caught fire at the site back in 2013 (ARIA 44622).