Lead-acid battery – lessons learned
On board a vessel, a starter battery for an auxiliary engine exploded. The batteries on board were purchased as maintenance-free and had a replacement interval of 5 years in the vessel's maintenance system.
In another incident on a different vessel, an engine room crew member was attempting to start a generator. He had a failed start on the first attempt and tried again. The second attempt caused one of the batteries in the battery casing to explode.
After the battery exploded, hydrogen gas and battery acid were released, but the battery casing was effective in containing most of it. Circuit breakers were turned off, and ventilation for exhaust was started. The crew member then exited the engine room but inhaled some fumed. The Poisons Informations Centre and the battry manufacturer were contacted.
Cause
The cause of the explosions was likely a lack of fluid in the battery, leading to the formation of hydrogen gas.
A lack of fluid in a maintenance-free battery can occur with low voltage and increased current draw, causing the fluid to "boil" out due to overheating.
Measures
Both vessels have ordered new batteries.
One of the shipping companies is also considering changing the battery replacement interval from five to three years, where they believed they had maintenance-free batteries.
Lessons learned
Shipping companies and crew must have good start-up routines and always ensure that chargers are turned on and delivering power. If the voltage is too low to start the engine, repeated starting attempts should be avoided as this can increase the risk of explosion.
For lead-acid batteries, sufficient ventilation must always be ensured where the batteries are located.
We also recommend that everyone keeps track of the batteries on board in terms of maintenance and inspections. Always ensure that battery maintenance is at least in accordance with the manufacturer's recommendations for the battery type.