Hazard potential from equipment using enclosed rechargeable batteries

A member has reported that a damage event occurred recently at one of their workshop facilities, where a sealed housing containing a rechargeable battery pack exploded. In this incident a Divescan system was in the process of being assembled and tested, and the system was being powered by its uninterruptable power supply (UPS) component.

At the end of the test, when the technician switched off the power from the UPS, the UPS housing lid blew off, bounced off a shelf at eye level, and landed some distance away in the workshop area. Fortunately, it missed the technician and he was not injured.

Further to this particular incident, a CTD (conductivity, temperature and depth) probe battery casing on ROV operating one of the member’s vessels on also exploded; again without injury.

As a result of these two common undesired events, the following procedures, have been issued by the company concerned:

• Always closely inspect the equipment containing rechargeable batteries, prior to, and after use, for any signs of external damage, water ingress, broken connectors etc. In cases where there is damage or damage is suspected, competent personnel only should examine such equipment further – before it is then used;
• Equipment containing rechargeable batteries should be subject to an annual inspection by competent technical personnel who have received the appropriate product training;
• When carrying out maintenance on such equipment, especially if enclosed in a pressure housing, always consider that the equipment could potentially be pressurised and take all necessary precautions when handling and dismantling the unit. (i.e. wear a full face mask, dismantle the end cap assembly of the subsea housing pointing it away from yourself and other personnel.);
• When the equipment requires an external unit to charge the batteries, always use the charger specified by the manufacturer of the equipment, thus minimising risk of damage to the equipment or harm to the operator;
• Operators of such equipment must use the correct charging procedure outlined in the manufacturer’s operating instructions;
• Battery condition and replacement history should be recorded by a notice attached to the equipment and in the planned maintenance records.