Lithium-ion batteries power phones, laptops, tools and electric vehicles. Most are safe in normal use, but damaged, poor-quality or incorrectly used batteries can cause a serious fire. E-bike and e-scooter incidents illustrate the risk: London Fire Brigade attended 206 in 2025. This guide explains causes, warning signs, prevention and the importance of evacuating promptly.
Reviewed 15 October 2026. The figures below cover London e-bike and e-scooter fires in calendar 2025, not all lithium-ion battery fires across the UK. They come from London Fire Brigade's January 2026 publication; practical advice draws on government and fire-service guidance.
Key facts and figures
- 206 — e-bike and e-scooter fires attended by London Fire Brigade in 2025.
- 171 — of those London fires involved e-bikes in 2025.
- 35 — of those London fires involved e-scooters in 2025.
- 20% — rounded increase from 171 London e-bike/e-scooter fires in 2024 to 206 in 2025.
- Clear exits — keep charging and stored batteries away from escape routes.
- Stay out — a damaged battery may remain hazardous after visible flames stop.
How lithium-ion batteries work
A lithium-ion cell transfers lithium ions between two electrodes through an electrolyte. A separator helps keep the electrodes from making direct contact. Internal damage or a fault can release energy as heat, and protective systems may be unable to stop a severe failure.
Battery packs differ in chemistry, size, construction and protective systems. Stored energy matters, but cell count alone does not predict the outcome of a failure. Rechargeable lithium-ion cells should not be confused with burning lithium metal or treated simply as a Class D metal-fire risk.
What is a lithium battery fire?
A failing lithium-ion cell can enter thermal runaway: heat-producing reactions accelerate and can spread to neighbouring cells. Fire, gas release and rupture may follow. A fire involving a battery does not always begin inside the cell; an external fire or other damage can also trigger failure.
Battery failure can produce intense heat and toxic, flammable gases. Apparent flame extinction does not establish that the battery is safe. Leave assessment, cooling and any continued monitoring to emergency responders; there is no single temperature or waiting period that makes every damaged pack safe.
What causes lithium battery fires?
Several faults or conditions can increase the risk of battery failure. Product-safety guidance highlights poor-quality products, damage and improper use:
- Incorrect charging — an incompatible or faulty charger can defeat the intended charging limits and cause dangerous overheating.
- Physical damage — crushing, impact, puncture or other damage can affect cells and their protective components.
- Poor-quality products — defective batteries, chargers or conversion kits may lack effective safeguards.
- Heat and unsuitable storage — direct heat, strong sunlight and inappropriate charging conditions can increase risk.
- Modification or deterioration — tampering, worn components or a change in battery behaviour need attention; do not keep using a damaged or suspect pack.
The hazards of a lithium battery fire
A failing battery can develop rapidly and obstruct escape. The main hazards to consider are:
- Violent failure — cells can rupture and eject hot or burning material; do not approach or try to move a failing pack.
- Toxic smoke and gases — fumes are hazardous to breathe. Leave immediately rather than investigating the source.
- Continuing internal reactions — extinguishing visible flames may not stop the reactions within the cells.
- Renewed fire — damaged cells can remain hazardous, so responders must assess the risk before the area or equipment is handled.
| Aspect | Common combustible-material fire | Lithium-ion battery fire |
|---|---|---|
| Driver | Burning fuel, heat and oxygen | May include internal thermal runaway and cell-to-cell spread |
| Heat | Depends on the fuel and conditions | Can develop rapidly and damage adjacent cells |
| Toxic gases | Smoke can contain toxic gases | Toxic smoke and potentially flammable gas releases |
| Suppression | Agent must match the fuel and conditions | Specialist assessment; do not attempt DIY suppression |
| Reignition risk | Hot material can reignite | Damaged cells can remain hazardous after flames stop |
How to prevent lithium battery fires
Buying suitable equipment, following instructions and keeping escape routes clear reduce risk. Government advice for e-cycle users and fire-service battery guidance explain practical precautions:
- Buy from a reputable supplier — use compatible batteries and chargers approved by the manufacturer, and check for product recalls. A safety mark alone is not a guarantee against a defective product.
- Charge while awake and present — follow the manufacturer's instructions, unplug when charging is complete and keep the device away from bedding and other combustible material. Never charge in an escape route.
- Use suitable conditions — keep away from heat and direct sunlight, let a battery cool after use and follow its specified charging and storage temperatures.
- Act on warning signs — swelling, unusual heat, leaking, smells or sounds mean stop using and charging the battery. If it is smoking or failing, leave immediately; do not pick it up or carry it outside.
- Arrange safe disposal — never put batteries in general waste or mixed recycling. Ask the council or specialist collection service how to handle a damaged battery; do not take an actively failing battery anywhere yourself.
Responding to a lithium battery fire
If a battery smokes, catches fire or shows signs of dangerous failure, get out, stay out and call 999 from a safe place. Alert others as you leave. Do not attempt to extinguish it or move it outside. London Fire Brigade's advice explains why these incidents need an urgent response.
Responders select the appropriate firefighting and monitoring arrangements for the equipment and conditions. Workplace managers should assess battery charging and storage, detection and escape arrangements in advance. Government guidance for premises covers these responsibilities; an ordinary extinguisher provision should not be assumed to control thermal runaway.
Make sure your workplace has trained fire wardens who understand modern fire risks.
Explore the Fire Warden / Fire Marshal Course →Sources & references
- London Fire Brigade: 2025 e-bike and e-scooter fire totals
- Department for Transport: battery safety for e-cycle users
- Department for Transport: managing battery fire risk in premises
- Office for Product Safety and Standards: buying and charging safely
- Devon & Somerset Fire & Rescue Service — Lithium battery fires
- London Fire Brigade — E-bike and e-scooter battery safety
Mark writes about workplace fire safety, compliance and online training for Fire Marshal Training, part of Online CPD Academy.