What to Do If a Battery Starts Swelling

A battery that is swelling, hot or hissing is a battery that is failing, and the first thing to do is the same whatever the device: stop using it and stop charging it straight away. Unplug it if it is on charge. Do not press the swollen part, do not try to open the casing, and do not put it in the bin. The London Fire Brigade's advice is to stop charging immediately and contact the manufacturer or a certified technician¹.

That applies to a phone, a laptop, a power bank, a power tool battery, a vape or an e-bike battery. The National Fire Chiefs Council says you must stop using or charging your battery immediately if you notice overheating, deformation, noise, smell, performance problems or smoke². The Scottish Fire and Rescue Service puts it just as plainly: do not use or charge your device if the battery is producing smoke, feeling extremely hot to touch, looking swollen or has any type of lump or leak, making a hissing or cracking sound, smelling unusual, or taking longer to charge or not fully charging³.

What follows is what to do in the first few minutes, where to put the battery while you wait for advice, who to contact, and why the temptation to puncture it, press it flat or bin it is the one thing you must resist.

Stop using and charging it straight away

The moment you notice swelling, heat, a hiss or a smell, the battery has told you it is no longer safe to use. The London Fire Brigade's instruction is to stop charging immediately¹. Merseyside Fire and Rescue Service says to stop using batteries that are swollen, damaged or overheating⁴. The National Fire Chiefs Council's Charge Safe campaign is equally direct: stop using or charging your battery immediately if you notice any of the warning signs².

If the device is plugged in, unplug it. Oxfordshire County Council's fire safety guidance says to stop charging immediately and unplug the device if it is charging⁵. Do not simply switch off at the wall and leave the charger connected; take the plug out.

Then leave it alone. Do not try to squeeze the swollen case back into shape, do not press the screen or lid flat, and do not attempt to remove the battery yourself. The London Fire Brigade says do not remove the casing or tamper with the equipment¹. Oxfordshire County Council is blunt about the same point: do not ever try to open or fix it yourself⁵.

Once it is unplugged, keep it away from anything that could catch fire. The Scottish Fire and Rescue Service advises avoiding charging batteries near flammable materials, not overloading power sockets and not using unsuitable extension cords³. Those are charging rules, but the same instinct applies to a battery you have just taken off charge: give it space, keep it off soft furnishings, and do not cover it.

Where to put it while you wait for help

There is no single official instruction that says "put a swollen battery in a metal tin in the shed", so do not invent one. What the guidance does say is consistent: stop using it, unplug it, do not tamper with it, and keep it away from flammable materials¹. A hard, non-flammable surface away from curtains, bedding, paper and other soft furnishings meets that description.

Keep it where you can see it and where children and pets cannot reach it. Do not put it in a cupboard, a drawer, a bag or a box, and do not cover it. The London Fire Brigade warns against covering batteries that are on charge in case of overheating⁶, and the Scottish Fire and Rescue Service says do not cover the charger, battery or device while charging because this can cause overheating or even a fire³. A battery that has already shown warning signs deserves at least the same care.

If the battery is hissing, smoking or getting hotter, do not handle it. Move yourself and others away, and be ready to call 999 if a fire starts. The London Fire Brigade's guidance for vape batteries is to stop using the battery immediately if it gets unusually hot, starts to bulge or starts hissing, and to leave it in a safe place until you can dispose of it properly⁶.

For more on what to do if a battery actually ignites, see what to do if a lithium battery catches fire.

Contact the manufacturer or a certified technician

The London Fire Brigade's advice for a swelling battery is to contact the manufacturer or certified technician¹. That is the route to take for any device, whether it is a phone, a laptop, a power bank or a portable power station.

Electrical Safety First gives the same instruction in slightly different words for each type of device. For mobile phones and tablets, if you notice odd smells, sparking, smoke, swelling, cracks or damage while charging, unplug immediately and contact the retailer and/or manufacturer⁷. For laptops, the wording is identical⁸. For power banks, again: unplug immediately and contact the retailer and/or manufacturer⁹. For chargers generally, unplug immediately and contact the retailer and/or manufacturer¹⁰.

If the battery is in an e-bike or e-scooter, the London Fire Brigade says to stop using the battery and seek advice from the manufacturer or retailer¹¹. Electrical Safety First adds that if you suspect a sub-standard or faulty e-bike charger or battery, you should stop using it immediately and report the fault to the manufacturer or retailer, or call the Citizens Advice helpline on 03454 04 05 06¹².

For a faulty product more generally, Electrical Safety First says to unplug it and contact the retailer, manufacturer or a qualified repair technician¹³.

When you call, have the model number and proof of purchase to hand. The National Fire Chiefs Council advises registering your product with the manufacturer to validate any warranties, noting that batteries are usually included in warranties, and that registering makes it easier for manufacturers to contact you in the event of safety or recall information¹⁴.

Why you must never puncture, press or bin it

A swollen battery is full of stored energy, and damaging it further can release that energy as heat and fire. Electrical Safety First warns that damaged batteries, including those that have been dropped, crushed or punctured, can become volatile and should not be used⁸. The London Fire Brigade says to protect batteries against being damaged, crushed, punctured or immersed in water¹. The same guidance appears for vape batteries: protect them against being damaged, crushed or punctured and do not immerse in water⁶.

So do not press the bulge, do not pierce the casing to "let the gas out", do not put it in water, and do not try to prise the battery out of the device. Oxfordshire County Council's instruction is not to open or fix it yourself⁵.

Nor should it go in the household bin. The London Fire Brigade's guidance for vape batteries is to leave a hot, bulging or hissing battery in a safe place until you can dispose of it properly⁶. The Scottish Fire and Rescue Service says a damaged battery should be recycled and should not be used or charged³. Devon and Somerset Fire and Rescue Service says that if a battery shows signs of overheating, swelling or other forms of damage, do not use it, dispose of it appropriately and report the defect to the manufacturer¹⁶.

For disposal, Oxfordshire County Council says to contact the manufacturer for specific advice on how to dispose of a damaged battery or device safely, and to confirm that it is safe to transport it⁵. In Wales, household waste recycling centres accept damaged or swollen batteries, but you should handle them with care and tape the terminals, and check with the centre first⁴.

Signs a battery is swelling, and what they mean

Swelling is the most visible sign, but it is not the only one. The National Fire Chiefs Council lists swelling or deformation, where the battery appears swollen, misshapen or has developed a lump². The London Fire Brigade says a battery that appears swollen or misshapen is a strong sign that it is failing¹¹. Oxfordshire County Council lists a battery that is swelling or expanding as a warning sign⁵.

The Scottish Fire and Rescue Service gives the fullest list: producing smoke, feeling extremely hot to touch, looking swollen or having any type of lump or leak, making a hissing or cracking sound, smelling unusual, or taking longer to charge or not fully charging³. The London Fire Brigade adds unusually hot, swelling or bulging, unusual smells and significantly reduced performance¹¹.

Check your batteries regularly. Electrical Safety First says to regularly check the condition of the battery for signs of swelling, dents, deformities and signs of overheating, and if you notice any damage, stop using and charging the battery immediately and replace it¹⁸. The same advice appears for e-bikes¹⁷ and e-scooters¹². The Scottish Fire and Rescue Service says batteries can be damaged by dropping them or crashing e-bikes or e-scooters, and where the battery is damaged it can overheat and catch fire without warning and should be replaced, not used or charged¹⁹.

For a fuller guide to the warning signs, see warning signs a lithium battery is dangerous.

Swollen phone, laptop or power station battery: what differs

The core instruction is the same for every device, but the detail differs slightly by what the maker and the safety bodies say about that type of product.

Phones and tablets. Electrical Safety First says that while charging, if you notice odd smells, sparking, smoke, swelling, cracks or damage, unplug immediately and contact the retailer and/or manufacturer⁷.

Laptops. The same wording applies: unplug immediately and contact the retailer and/or manufacturer⁸. Electrical Safety First also warns that damaged batteries, including dropped, crushed or punctured ones, can become volatile and should not be used⁸.

Power banks and portable power stations. Electrical Safety First says that while charging, if you notice odd smells, sparking, smoke, swelling, cracks or damage, unplug immediately and contact the retailer and/or manufacturer⁹. A portable power station contains the same kind of lithium cells as a power bank, so the same caution applies. For more on power stations specifically, see portable power stations: what they do and how to choose.

E-bikes and e-scooters. The London Fire Brigade says to stop using the battery and seek advice from the manufacturer or retailer if you notice warning signs¹¹. The National Fire Chiefs Council says to stop using or charging immediately if you notice overheating, deformation, noise, smell, performance problems or smoke². Electrical Safety First says to stop using and charging the battery immediately and replace it if you notice any damage¹⁷.

Vapes. The London Fire Brigade says that if the battery gets unusually hot, starts to bulge or starts hissing, stop using it immediately and leave it in a safe place until you can dispose of it properly⁶.

Power tools. Electrical Safety First's guidance for cordless heat guns says that if the battery emits any unusual odours, sparks, smoke, swelling, cracks, or you see any form of damage, stop using the battery immediately and make sure it is unplugged from the charger²⁰.

Hoverboards and self-balancing boards. Electrical Safety First says to regularly check the condition of the battery for signs of swelling, dents, deformities and signs of overheating, and if you notice any damage, stop using and charging the battery immediately and replace it¹⁸.

Battery hot or smoking: when to call 999

A battery that is hot, smoking or hissing has moved beyond a swelling battery into something that could catch fire. The London Fire Brigade's advice for vape batteries is to stop using it immediately if it gets unusually hot, starts to bulge or starts hissing, and to leave it in a safe place until you can dispose of it properly⁶. Fire and rescue service advice for e-bike and e-scooter batteries is that if a battery becomes unusually hot to the touch, stop using it and allow it to cool²¹.

If it is smoking, do not pick it up. Move away, keep others away, and call 999 if a fire starts. The London Fire Brigade's easy-read fire safety booklet says to keep an eye out for warning signs that a battery might be failing and becoming a fire risk²². Fire and rescue service advice is that if a battery shows signs of swelling, overheating or emitting smoke, safely remove it and report the incident to appropriate authorities²³.

If a fire does start, get out, stay out and call 999. Do not try to move a burning battery. For more, see what to do if a lithium battery catches fire.

Charging safely to prevent the next one

Most of the advice that prevents a swollen battery is the same advice that prevents a battery fire. The National Fire Chiefs Council's Charge Safe campaign says to stop using or charging your battery immediately if you notice any of the warning signs². The London Fire Brigade says to protect batteries against being damaged, crushed, punctured or immersed in water¹.

The Scottish Fire and Rescue Service advises avoiding charging batteries near flammable materials, not overloading power sockets and not using unsuitable extension cords, and always using uncoiled extension leads that are properly rated for your devices³. It also says not to cover the charger, battery or device while charging, as this can cause overheating or even a fire³. The London Fire Brigade says not to charge under pillows or blankets⁴.

For a full set of charging habits, see the safe battery charging at home checklist. For the wider picture on lithium battery safety, see lithium-ion battery safety at home.