​​Lithium-ion battery fire safety guidance

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Lithium-ion batteries are now widely used in everyday life

equipment, including laptops, mobile phones,

power tools, e-bikes, e-scooters, battery energy storage

systems and electric vehicles.

 

While most operate safely, failure can result in rapid fire

development, intense heat release, and the production

of toxic and flammable gases.

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Why lithium-ion battery fires are different

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Lithium-ion batteries store large amounts of energy within multiple small cells. If a single cell fails, it can enter thermal runaway — a self-heating chemical reaction that generates more heat than can be dissipated. This can quickly spread to adjacent cells, causing fire, jet flames, or an explosion.

Unlike conventional fires:

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• Lithium-ion battery fires do not rely on external oxygen once thermal runaway occurs

• They may re-ignite after appearing to be extinguished

• They produce toxic smoke and flammable off-gases early in the failure process

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Common causes of battery failure

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Battery failure can occur even when a battery is not fully charged. Known causes include:

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• Use of incorrect or incompatible chargers

• Over-charging or electrical faults

• Physical damage such as dropping, crushing or puncturing

• Internal manufacturing defects

• Exposure to external heat sources

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Importantly, damaged batteries may ignite hours, days, or weeks later.

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Charging safety – the highest risk activity

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Charging presents the greatest fire risk and should be carefully controlled:

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• Only use manufacturer-approved chargers

• Do not charge batteries unattended or overnight

• Never charge in escape routes, stairways or corridors

• Charge on non-combustible surfaces, away from combustible materials

• Allow batteries to cool before charging if they are warm from use

• Unplug chargers once charging is complete

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Storage and location controls

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• Do not store or charge batteries near heat sources or ignition sources

• Avoid storing e-bikes, e-scooters or spare batteries in escape routes or under stairs

• Where multiple batteries are present, consider dedicated storage or charging areas

• For higher quantities or higher-risk batteries, fire-resistant enclosures or cabinets may be appropriate

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Signs of battery failure

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Remove batteries from use immediately if any of the following are observed:

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• Swelling, bulging or cracking

• Hissing noises or unusual smells

• Excessive heat

• Smoke or vapour

• Leaking electrolyte

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What to do if a battery overheats or catches fire

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• Raise the alarm and evacuate if necessary

• If safe to do so, disconnect power

• Close doors to limit fire and smoke spread

• Call the Fire and Rescue Service

• Do not attempt to move a battery that is actively failing

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Portable water or water-based extinguishers may be used only to prevent fire spread to nearby materials, not to extinguish the battery itself.

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Management responsibilities

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Schools and workplaces should ensure:

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• The Fire Risk Assessment considers lithium-ion battery risks

• Clear rules are in place for charging and storage

• Staff are trained to recognise damaged or failing batteries

• Damaged or waste batteries are stored safely and removed promptly

• Emergency procedures reflect the presence of lithium-ion batteries

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E-scooters and e-bikes – specific fire risks

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E-scooters and e-bikes present an elevated fire risk due to their high-energy battery packs, frequent charging cycles, and increased likelihood of non-OEM chargers or modified batteries.

 

Key risk factors include:

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• Charging in hallways, stairways or other escape routes

• Overnight or unattended charging

• Use of incorrect, damaged, or non-manufacturer chargers

• Batteries that have been dropped, knocked or involved in minor collisions

• Storage in small rooms without fire separation

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Where possible:

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• E-scooters and e-bikes should be charged and stored away from occupied areas

• Charging should be avoided in schools, residential buildings and communal areas

• If charging indoors cannot be avoided, devices should be kept in a room where a fire door can be closed to contain fire and smoke​