Lessons Learned: Battery Explosion Highlights Risks of Improper Maintenance

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The UK Marine Accident Investigation Branch (MAIB) published Safety Digest 1/2025, highlighting safety issues from recent marine incidents. The International Marine Contractors Association (IMCA) reviewed the findings and shared selected cases of interest. One such case involved a battery explosion on a barge.

What Happened

A crew member narrowly avoided injury when a set of four lead-acid batteries exploded as the generator engine was started after routine checks. The explosion occurred at the moment the start solenoid engaged to activate the starter motor. Fortunately, the batteries were housed in a secure steel locker that effectively contained the blast and minimized further damage.

Why It Happened

The batteries had been in service for over five years and were of the valve-regulated lead acid (VRLA) type. This type was unsuitable for the vessel’s continuous float charging system. Over time, the electrolyte level likely decreased, exposing the cell plates. Corrosion of these exposed plates led to internal short-circuiting under high discharge load, resulting in the explosion. The battery charging system itself was functioning correctly and delivering the intended trickle charge.

Actions Taken

While no immediate corrective actions were detailed, the investigation highlighted issues related to battery type suitability and the importance of long-term maintenance planning.

Lessons Learned

  • Batteries must be treated as critical equipment with a dedicated maintenance log. 
  • Each battery should be tracked by type, location, service start date, inspection or maintenance history, corrective actions (if any), and replacement schedule.
  • Batteries must be selected based on compatibility with the vessel’s charging configuration to prevent long-term degradation and risk of failure.
  • Batteries should be stowed in well-ventilated, purpose-built lockers to manage gas build-up and reduce fire or explosion risks. 
  • Lockers should be placed in cool, dry areas and fitted with corrosion-resistant, explosion-proof light fittings.

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Source: IMCA Trading Ltd