If a battery cell creates more heat than it can effectively dissipate, it can lead to a rapid uncontrolled release of heat energy or thermal runaway, which can result in fire and/or an explosion. The most likely causes are from physical or chemical damage, heat, over-charging / over-discharging or defective manufacturing.  

Thermal runaway can lead to the ejection of a range of gases. If a battery vents or ruptures due to a thermal runaway, immediate ignition of the emitted gases can occur. Alternatively the gases can spread, unignited, with the potential for a very rapid combustion or explosion. This can lead to a secondary fire and therefore spreading the original fire further.

The highest risk of a fire occurring is when a battery: 

• is being charged.
• is being transported, therefore at increased risk of damage.
• has been damaged previously, as thermal runaway can occur hours, days or weeks later.
• has been abused from over-charging or continual charging and discharging.

Only charge batteries with a suitable Original Equipment Manufacturer (OEM) or compatible charger.

Charging of batteries should be completed in a separate building, where possible 10m from main building and critical plant, or within a minimum 90 minutes fire rated enclosure. This could be an internal room, proprietary cabinet or bespoke container, depending on specific requirements. Batteries shouldn’t be left charging in unoccupied areas or premises.

Small size batteries e.g. those used in hand-held scanners, should be charged in a proprietary cabinet, internal to the building. These should have a minimum of 90 minutes fire rating. Depending on the nature of the risk and exposure, fire detection and suppression within the cabinet, maybe appropriate.

Charging of e-bike and e-scooters within residential buildings should be avoided. Where this can’t be avoided, they must not be charged in communal areas or on fire exit routes. Where batteries can be removed from e-bikes then this should be encouraged. 

All lithium-ion batteries that are thought to be faulty, considered to be outside the manufacturers lifespan or showing signs of damage, should be quarantined. A suitable and sufficient enclosed container should be provided and kept at least 10 metres from the building. This could be something simple, e.g. a metal container with close fitting metal lid, filled with vermiculite granules.

Proprietary transport containers can be used, complying with the Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations (CDG), so they are ready for safe transporting. The regulations state that packaging should be leak-proof, with suitable inner and outer containers. The batteries should be encased in a proprietary non-combustible and electrically non-conductive thermal insulation material, e.g. vermiculite.

All quarantined batteries should be removed from the premises, on a regular basis, by a competent contractor and returned to the manufacturer for disposal. 

Firefighting of a fire involving lithium-ion batteries must be left to the Fire and Rescue Service. Large lithium-ion storage areas will need special consideration around firefighting water run-off.

Consultation with the local Fire and Rescue Service should be undertaken, at an early stage of planning, for large storage areas, as well as enclosed and or basement areas.

Unlike lithium batteries, lithium-ion batteries do not contain lithium metal, which is highly combustible and reactive with water. Currently it’s accepted that water is the best medium to fight a lithium-ion battery fire, due to its effective cooling capabilities. Getting adequate quantities of water and directly to the battery can be a challenge. Specialist products have been developed which may be suitable for a small-scale battery fire or for life safety / escape purposes, e.g. specialist fire extinguishers, fire blankets or gloves.

Where sprinkler protection is installed the system could suppress a fire but it may not fully extinguish. It’s recognised that even a small lithium-ion battery fire could overwhelm sprinklers and therefore containment of a fire is key.

The Fire Protection Association provide further information in their guides:

• Lithium-ion battery use and storage need to know guide (FPA RE2).
• Recommendations for the storage, handling and use of batteries (FPA RC61).