Rail Safety Investigation - Uncontained battery failure involving Sydney Light Rail vehicle 053 - Randwick LRV depot - 03 April 2020

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What happened

On 2 April 2020, a battery enclosure cover of a light rail vehicle flew off after the battery was ruptured.

What we found

The software controlling the battery charging likely corrupted during the uploading process which went undetected. The fault with the software resulted in overcharging the batteries on multiple LRVs, including LRV 053.

The overcharging of batteries was not detected prior to the occurrence through Alstom’s validation or fault monitoring processes. The overcharging of LRV 053 batteries generated excessive hydrogen within the batteries.

The battery enclosure on LRV 053 ruptured when flammable gases were released into the enclosure in the presence of an ignition source.

The risk of explosion had been identified although relied on risk controls that were ineffective at preventing the escalation in this instance.

What has been done as a result

There's been several recommendations put forward to try preventing this incident from happening again.

They include:

• Alstom changed the management of train fault data to generate automatic alerts for battery over temperature faults
• a new fault code was introduced to monitor the battery charging temperature
• new software testing has been introduced by both the manufacturer and software maintainer.