E-bike and e-scooter battery fire risks
Lithium-ion battery fires are fast-moving, toxic, and extremely difficult to extinguish. With e-bike and e-scooter ownership rising sharply, fire brigades are reporting a significant increase in related incidents. Here is what you need to know before you charge.
If your battery is smoking, swelling or hot:
- Do not touch the battery or try to move the bike
- Leave the room and close the door behind you
- Alert everyone in the building and evacuate
- Call 999 (UK) or 911 (US) from outside
Safe charging rules
Six rules to reduce the risk before you plug in
Only use the manufacturer-supplied or approved charger
Third-party chargers are a leading cause of battery fires.
Never charge overnight or when you are asleep
Fires can develop quickly — you need to be awake to escape.
Do not charge in a hallway or on a stairwell
A fire here blocks the primary escape route.
Inspect the battery for damage before charging
Swelling, cracking or leaking electrolyte means replace, not charge.
Charge at room temperature — not in extreme heat or cold
Temperatures below 0°C or above 40°C stress the cells.
Fit a smoke alarm in the charging room
Interlinked alarms give earlier warning in adjacent rooms.
What is thermal runaway?
Thermal runaway is a chain reaction inside a lithium-ion battery cell where heat causes internal components to break down, releasing more heat and flammable gases. Once it starts, it cannot be stopped by removing the charge source. Gases ignite and the cell vents violently; in a multi-cell battery pack, the reaction rapidly propagates to adjacent cells. Temperatures can exceed 400°C (750°F). Fires produce toxic hydrogen fluoride gas and cannot be extinguished by conventional means — only large volumes of water can cool the cells enough to prevent reignition.
Where not to charge
The London Fire Brigade has recorded deaths in fires where an e-bike was charged in a hallway, blocking the only exit. Charging in a living room, bedroom, or on a stairwell creates the same risk. Ideal charging locations are a garage, shed, or external storage unit with no connection to the main living area. If charging indoors is unavoidable, choose a room you can seal off from the rest of the property and fit an interconnected smoke alarm.
5 min
Approximate time for a thermal runaway fire to fully engulf a room from initial ignition. Source: London Fire Brigade.
How to buy more safely
The highest-risk batteries are cheaply manufactured cells without proper safety management circuitry, often sold via unregulated online marketplaces. Look for an approved safety mark — CE and UKCA in the UK, UL listing in the US — and buy from reputable retailers. The Electrical Safety First guidance has a checklist of what to look for before purchasing, including cell chemistry and battery management system (BMS) requirements.
For broader context on home fire escape, see our get out, stay out guide and the two-ways-out escape planning guide.
Sources: London Fire Brigade · Electrical Safety First · NFPA · US CPSC
E-bike battery FAQ
Questions about lithium battery fire risks
Lithium-ion batteries can enter a process called thermal runaway — a self-sustaining chain reaction where heat causes internal components to break down and release more heat, eventually causing the cell to vent flammable gases and ignite. Triggers include overcharging, physical damage to the cell, manufacturing defects, use of incompatible chargers, and charging at extreme temperatures. Once thermal runaway begins in one cell it spreads rapidly to adjacent cells; fires can intensify very quickly with little warning. See the London Fire Brigade's e-bike fire guidance for more detail.
Charging indoors is common, but carries a higher life-safety risk than outdoor charging if a fire starts. The London Fire Brigade strongly advises not charging in a hallway, on a stairwell, or in any room that is a primary escape route. If you must charge indoors, do so in a room with a closing door, away from sleeping areas, and never overnight. Keep a working smoke alarm in the room and consider an interlinked alarm system.
No. You should only use the charger supplied by the manufacturer or a replacement charger that is officially approved for your specific battery. Third-party chargers may not regulate voltage or current correctly, which can overcharge the battery and trigger thermal runaway. This is one of the most common causes of e-bike battery fires. Check that any charger carries an approved safety mark (CE, UKCA, or UL) and is rated for your battery's exact voltage.
Do not touch the battery. Evacuate the room or building immediately — close doors behind you to slow the spread. Call 999 (UK) or 911 (US). Do not attempt to move the bike or battery, and do not pour water directly on a lithium battery fire (it does not extinguish it and can spread electrolyte). Once outside, stay outside. These fires can reignite minutes or hours after appearing to be extinguished. Follow the get out, stay out steps at all times.
Yes — e-scooters, electric unicycles, and hoverboards use the same lithium-ion cell chemistry and carry the same thermal runaway risk. UK fire brigade data shows a significant proportion of incidents involve e-scooters and hoverboards, particularly those purchased cheaply online without safety certification. The Electrical Safety First guidance on e-bikes and e-scooters has advice on checking for safety marks before purchase.