Safety and health newsletter for the Oregon construction industry

February 18, 2014


Preventing battery explosions

A battery that exploded while being charged

Consider this scenario: A worker uses a 12-volt battery charger to charge a 24-volt lead-acid battery. When the worker realizes that the 24-volt battery is not charging (after three to five minutes), he turns the charger off and the battery charger explodes. What caused the explosion?

An overcharged lead-acid battery will produce hydrogen gas as water in the battery decomposes into oxygen and hydrogen. If the rate of overcharge is small, the gas may dissipate through vents in the battery's cells. But if the overcharge is severe, a flammable concentration of hydrogen can build up in the cell or in the battery enclosure and an open flame or a spark can cause an explosion.

Never use a 12-volt battery charger to charge a 24-volt lead-acid battery system. In the above scenario, the 24-volt battery discharged into the 12-volt battery. In the three to five minutes that the worker was waiting for the battery to charge, a flammable concentration of hydrogen gas was building up in the charging unit. When the worker turned the charger off, a spark ignited the hydrogen gas and the battery exploded.

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