The battery is much hotter than usual, you hear hissing, popping or crackling, or you smell a sweet, sharp or chemical smell, or see smoke or vapour. These are London Fire Brigade's warning signs of a failing lithium battery. They can mean a cell has started to overheat by itself (thermal runaway), which can spread to the other cells and become a fierce fire with toxic smoke in a very short time. Act now. Do not wait to see if it gets worse.
Normal warmth is different: batteries can be warm after riding or charging (Gogoro notes its batteries may become hot after use). Warm is normal. Too hot to keep your hand on, or with any sound, smell or smoke, is not.
Is it safe to ride?
Stop now. Do not ride, charge or move the bike indoors.
Quick checks first
There is no time for checks. Go straight to step 1.
Diagnose it step by step
1Is there smoke, vapour, flames, popping or hissing?
- Yes: get away and keep everyone away. Call the fire service. Do not try to put out the fire yourself (London Fire Brigade). If indoors, get everyone out and close the door behind you. Stop here.
- No: go to step 2.
2Is it charging?
- Yes: switch off at the wall and unplug at the wall (London Fire Brigade advises turning off and unplugging at once). Do not touch the battery. Go to step 3.
- No: switch the bike off. Go to step 3.
3Is the bike or battery indoors or near things that burn?
- Yes, and the battery is a swap battery that is not hot to touch and comes out easily: take it outside onto bare ground or concrete, away from buildings, vehicles and fuel. If it is hot, swelling or you are unsure, leave it, get everyone out, and call the fire service.
- It is already outdoors: keep people away.
4Is the heat or smell coming from the battery, or from the charger, plug or wiring?
- Battery: follow Handle a damaged battery pack. Report to the operator or dealer with the battery ID. Never reuse it without their check.
- Plug or socket only, no battery heat: see Charge plug or socket gets hot.
- Wiring: see Burning smell from the wiring.
5. Watch from a safe distance for several hours. Delayed fires are possible.
6. Find the cause later, with the operator or dealer. Common causes include an internal cell fault, earlier damage from a drop or crash, water entry, charging with the wrong charger, or charging straight after hard riding. Ather advises letting the battery cool after a long ride before charging and using only the original charger.
Causes, most likely first
| Cause | How to confirm | Fix |
|---|---|---|
| Internal cell fault or thermal runaway | Heat, hiss, smell, smoke | Fire service; Handle a damaged battery pack |
| Earlier physical damage | History of drop or crash | Handle a damaged battery pack |
| Water entry | Recent flood or deep water | Check a bike after water exposure |
| Wrong or faulty charger | Non-approved charger used | Stop using it; Check the charger and cable |
| Hot connector, not battery | Heat at plug only | Inspect the charge port and plug |