OSH alert - Cluster investigation - Battery rupture incidents (April 2016)

Key learnings from a high potential incident.

HPI OSH Alert #475

What happened?

A Cluster Investigation has been undertaken following a number of automotive starter battery ruptures. Whilst no injuries occurred as a result of these incidents there was potential for the events to:

  • inflict serious injuries, such as severe burns including eye damage
  • ignite and build fires
  • cause environmental impact from acid spill
  • cause business interruption.

The Cluster Investigation identified the common contributing factors and appropriate corrective actions to reduce the risk of further incidents. The data collected came from eight battery rupture related incidents that occurred between 2011 and 2016.


All ’automotive‘ type batteries produce hydrogen and oxygen during normal operation. Even when sitting idle, batteries generate small amounts of hydrogen due to self-discharge action. These gases are highly explosive. In some cases, damage to the battery makes it difficult to determine the exact cause of the explosion, but in most cases, one or more contributory causes can be identified. These include:

  • an ignition source in close proximity to battery, e.g. loose terminal creating sparks/arcing
  • loss of electrolyte due to overheating, overcharging or failure to maintain the correct level of electrolyte
  • a direct short circuit or sustained high current draw igniting excessive build-up of hydrogen gas within the battery.

Maintenance Free Batteries 

The term ‘Maintenance Free’ is widely used in the battery industry and is used to describe the battery grid composition that is manufactured from lead-calcium alloys as opposed to the traditional lead-antimony batteries. The batteries using lead-calcium alloys produce less gas when charging, resulting in less water consumption over the life of the battery. However, the term ‘Maintenance Free’ is misleading. These batteries can still lose water over an extended period, or if subjected to high temperatures and failure to replenish the water/electrolyte level in the battery can result in an explosion due to the excessive build-up of hydrogen gas within the battery. Maintenance Free batteries can be either ‘non-accessible’ or ‘accessible’. Accessible maintenance free batteries have caps to allow top up of electrolyte, whereas non-accessible maintenance free batteries are sealed and cannot be periodically topped up.

Photo of AC Delco 12V Battery – Rupture 19/1/2016

Photo of battery rupture

Common Factors

The common contributing factors amongst incidents in the cluster were:

  1. There was no electrical design standard for battery and charger selection for standby diesel gensets.
  2. The batteries were not fit for purpose. They were either the wrong type of battery for the application, or the incorrect battery and charger combination for the mechanical equipment.
  3. ‘Non-accessible’ ‘maintenance free’ automotive type batteries were used, often in high temperature environments. This meant that they lost water and could not be periodically topped up, in conjunction with constant float charging (WorkSafe Vic Safety Alert Nov 2012. Ref. ALE0158/01/11.12).
  4. Manual start-up of auxiliary gensets with operator in close proximity to the battery during test runs as per routine planned maintenance activities.

What are we doing to prevent this happening again?

  • Develop and publish an electrical design standard for battery/charger systems for diesel pumps and diesel generators.
  • Communicate the requirements of the new battery/charger design standard to all affected parts of the business (new Design Standard is scheduled for September 2016).
  • Inspect existing sites against new battery/charging design standard.
  • Undertake replacement as required following inspection.

Key learning

It is essential to have a systematic review of equipment in use and ensure guidelines exist for the selection, use, maintenance and replacement of batteries and charging systems for standby diesel generators/engines.


What key learnings can you discuss with your team to stop this from happening again?

  1.  Always protect yourself whilst working with or around batteries and charging systems
    • Ensure the risk has been captured in your JSEA and controls are identified.
    • Wear suitable PPE during maintenance and testing activities relating to batteries (i.e. minimum of goggles, hand protection and overalls).
    • Never lean over battery while testing and remove metallic jewellery, watches and wristbands prior to working on batteries.
    • Always confirm that you have access to eye-wash bottles or emergency shower prior to testing or maintaining batteries.
  2. The correct selection, use, maintenance and replacement of batteries and charging systems for standby diesel generators/engines is essential
    • What are the types of batteries and charging systems that we have in place?
    • What factors can increase the risk of battery ruptures?
    • What factors need to be checked during battery maintenance and regular inspections?
  3. What can we do now to control and reduce the risk of battery ruptures?
    • Identify and document where batteries and charging stations for standby diesel generators/engines are used in our work area.
    • Always maintain batteries in accordance with the equipment or manufacturer’s instructions.
    • Always top up ‘accessible type’ batteries with de-ionized or de-mineralised water only and maintain electrolyte levels at approximately 13mm above plate.

If you would like further information about anything included in this OSH Alert, please contact Charis Neumann, Senior OSH Analyst - Incidents, on (08) 6330 6629.