Warning over exploding lead-acid batteries

There have been four reported explosions involving lead-acid batteries in NSW open-cut coal mines since November 2015, prompting the Mine Safety Investigation Unit to issue a safety warning.

In two of these incidents, people were close to the explosion and one tradesman was sprayed with acid.

The batteries were installed in mobile and fixed plant applications — three batteries were sealed ‘maintenance free’ units and the other was a vented ‘maintainable’ battery.

Three of the events occurred while maintenance activities were in progress on the equipment. In events where the battery cases actually failed, debris was scattered up to 10 m from the equipment.

Investigations revealed several contributing factors, some of which were common to more than one of the events, including:

• The batteries were not the correct size or type (one was reportedly substantially undersized when compared to the required cold cranking amps for the machine on which they were installed);
• Workers with the responsibility for inspecting and testing the batteries did not have clear guidance or information on how to assess whether the battery condition was acceptable. In two events, the battery voltage was checked before the incident and the measured battery voltage provided an indication that the battery may no longer have been suitable for service;
• Adequate ventilation of battery enclosures was not given to prevent accumulation of hydrogen released while a battery was being charged;
• The batteries failed to be securely mounted and protected from the harmful effects of vibration.

To read the full safety bulletin and the list of recommendations, click here.