A 24V wet lead-acid mobile plant battery exploded whilst on charge at a quarry. The battery was in a locked storeroom at the time and no one was injured.
Investigation into the cause of the explosion found that the six cell caps on top of the battery had not been removed before charging, preventing hydrogen gas given off during the charging process from venting off safely. A build up of heat inside the battery is thought to have ignited the hydrogen gas, causing the battery to explode. There was no evidence of electrical sparking.