Safe system of work: Rechargeable batteries

Thermal imaging or scanning

Thermal imaging or scanning can be used to monitor rechargeable battery temperatures, which may provide an indication of thermal runaway. However, due to the location of rechargeable batteries, especially in modes of transport, it may not be possible to rely on thermal imaging or scanning to determine the extent of thermal runaway. For further information refer to Firefighting – Thermal imaging or scanning: Fire-related incidents.

Flammable vapours

As a precaution, it should be assumed that any vapours being emitted by rechargeable batteries could be toxic, corrosive or flammable, with the potential to present health or explosive hazards. The vapours may have the appearance of steam or white smoke.

If the presence of flammable vapours being emitted by rechargeable batteries is suspected or known, the following guidance should be considered:

• Hazardous materials: Physical hazards – Substance identification: Flammable vapours
• Hazardous materials: Physical hazards – Safe system of work: Atmospheric conditions
• Hazardous materials: Physical hazards – Cordon controls: Unignited flammable vapours
• Hazardous materials: Physical hazards – Eliminate or control ignition sources
• Hazardous materials: Physical hazards – Manage the release of flammable vapours
• Hazardous materials: Physical hazards – Use intrinsically safe equipment

If flammable vapours emitted by rechargeable batteries have ignited, the following guidance should be considered:

• Hazardous materials: Physical hazards – Substance identification: Flammable vapours
• Hazardous materials: Physical hazards – Cordon controls: Ignited flammable vapours
• Hazardous materials: Physical hazards – Prevent firespread: Flammable vapours
• Hazardous materials: Physical hazards – Select appropriate firefighting media: Flammable vapours

Respiratory protective equipment

Personnel should wear appropriate respiratory protective equipment (RPE) to protect them against the inhalation of toxic, corrosive or flammable vapours emitted by rechargeable batteries.

Detection, identification and monitoring

Detection, identification and monitoring equipment can be used to monitor the release of hazardous, corrosive or flammable vapours emitted from rechargeable batteries.

Fires involving rechargeable batteries

As the flammable vapours produced by thermal runaway in rechargeable batteries have the potential to build up in a room or compartment, with the potential to ignite, their presence should be considered before deploying personnel. It is important to consider that this hazard could be present in a building or in a mode of transport, or at any other location where there are rechargeable batteries.

As the effects of ventilation or the introduction of an ignition source, may cause the flammable vapours to ignite, firefighting activities need to include consideration of this occurring. For further information refer to:

• Firefighting – Situational awareness: Fires in rooms or compartments
• Firefighting – Recognise the signs and symptoms of flashover, backdraught and fire gas ignition
• Firefighting – Fire attack approaches: Fires in rooms or compartments
• Firefighting – Develop a ventilation strategy: Fires in rooms or compartments
• Firefighting – Tactical ventilation: Fires in rooms or compartments
• Firefighting – Firefighting: Fires in rooms or compartments

Firefighting media and techniques

Because batteries and their terminals are often sealed, firefighting media may be ineffective. However, water may be applied directly to the battery or its surroundings, in order to cool the battery and control firespread.

Water should not be applied directly to the exposed terminals of a battery if it has not been isolated or if there is a risk of electric shock. Firefighting operations can be hindered by the construction of some batteries that are designed to make them water resistant or waterproof. If personnel are in doubt about the correct firefighting techniques, they should seek specialist advice or consider manufacturer’s guidance.

Because of the difficulties associated with attempting to use extinguishing media on these batteries, internally they may become subject to thermal runaway. This reaction cannot be stopped by fire and rescue service actions and can lead to fires, explosions or sudden releases of flammable vapours or hazardous materials.

When attempting to extinguish a fire involving rechargeable batteries, additional resources may be required to provide sufficient firefighting media, potentially for an extended period of time.

Controlled burning

If it is determined that it is not feasible to extinguish a fire involving rechargeable batteries with the firefighting media available, or that doing so would result in unacceptable levels of pollution caused by fire water run-off, controlled burning may be considered.

It is unlikely that this would be considered a viable option for a building, especially a residential property. However, it may be a viable option for industrial or commercial sites, or for a mode of transport. The decision to proceed with controlled burning should be made with the appropriate responsible person or other agencies.

For further information refer to:

• Firefighting – Controlled burning
• Environmental protection – Controlled burning: Environmental considerations

Specialist relocation or removal of rechargeable batteries

Depending on the location and quantity of rechargeable batteries, it may be appropriate to relocate or remove them to mitigate the risk of their reignition. This activity can only be carried out by a specialist and will require arrangements to be established during pre-planning. As specialist relocation or removal of rechargeable batteries will attract a cost, fire and rescue services should determine their approach in policies and procedures.