Swollen Phone Battery: Warning Signs, Safety and Replacement

A swollen phone battery is a lithium-ion cell that has started to produce gas inside its pouch, which makes it expand and push against the screen or back panel. The most common signs are a screen lifting away from the frame, a back cover that bulges or cracks, a phone that rocks on a flat table, or a gap appearing along the edge. If you see any of these, stop charging and using the phone, power it off if it is safe to do so, keep it away from heat and anything flammable, and do not press, puncture or try to flatten it. A swollen battery cannot be fixed; it must be replaced and the old one recycled at a proper battery collection point. This guide is for anyone who has spotted a bulging phone. It covers the warning signs, the immediate safety steps, why batteries swell, how to dispose of one in the UK, and your replacement options.

Warning signs your phone battery is swollen

Swelling usually develops gradually, so the early signs are easy to miss. Check for:

• Screen lifting: one edge of the display rises from the frame, or the screen looks slightly domed.
• Back panel bulging: the back glass or plastic cover pushes outwards, or separates along the edge.
• Cracks with no impact: back glass or the screen cracks even though the phone has not been dropped.
• Phone rocks or spins: lay it face down and face up on a flat table. A healthy phone sits flat; a swollen one rocks.
• Touch or display problems: pressure from below can cause phantom touches, unresponsive areas or display marks.
• Creaking or a soft feel: pressing gently on the back feels spongy.
• Heat and poor battery life: the phone runs warm and the battery drains quickly or shuts down unexpectedly.
• Case no longer fits: a case that used to fit snugly suddenly feels tight.

Not every gap is a swollen battery; a phone that has been dropped can have a separated screen or bent frame. But if the gap grows over days, or several of the signs above appear together, treat it as a swollen battery until it has been checked.

What to do right now

Lithium-ion batteries store a lot of energy. A swollen one is a sign of internal damage, and damaged cells can overheat. These steps reduce the risk while you arrange a replacement:

1. Unplug it and stop charging. Charging a swollen battery adds energy to a damaged cell.
2. Power the phone off if you can do so without pressing hard on the screen.
3. Do not press, bend, squeeze or puncture it. Never try to push the screen back down, and never pierce the battery to "let the gas out".
4. Remove the case gently if it comes off easily, so the phone is not under pressure.
5. Move it somewhere safe: a cool place on a hard, non-flammable surface such as a tiled floor, a ceramic plate or a metal tin, away from bedding, paper and anything that could catch fire. Do not leave it in a hot car or in direct sunlight.
6. Back up your data only if the phone is cool and works normally without charging. If the phone is hot, hissing, smoking or smells unusual, do not touch it further.
7. If there is smoke, fire or heat you cannot safely approach, leave the room, close the door and call 999. Do not try to put out a battery fire with water from close range.

Electrical Safety First, the UK charity focused on electrical safety, publishes general guidance on safe charging and battery use at home.

Why phone batteries swell

Inside a lithium-ion battery, chemical reactions move energy in and out as you charge and use the phone. Over time and under stress, side reactions produce gas, and because a phone battery is sealed in a soft pouch, the gas makes it expand. The usual causes are:

• Age and charge cycles. Every battery wears with use. Apple explains how batteries age chemically on its iPhone battery and performance page; the same chemistry applies to Android phones.
• Heat. High temperatures speed up the reactions that degrade a battery. Leaving a phone in a hot car, charging it under a pillow, or gaming while fast-charging all add heat.
• Poor-quality chargers and cables. Chargers that do not regulate voltage correctly can stress the battery.
• Physical damage. A drop or bend can damage the cell internally, even if nothing looks wrong at first.
• Low-quality replacement batteries. Cells that do not meet OEM standard specifications, or that lack proper protection circuits, are more likely to fail early.
• Deep discharge and long storage. A battery left completely flat for months can be damaged when it is eventually charged.

How to prevent battery swelling

You cannot stop a battery ageing, but you can slow it down and reduce the risk of swelling:

• Keep the phone out of heat: no dashboards, radiators or sunny window sills.
• Charge on a hard surface, not under pillows or duvets.
• Use a reputable charger and cable that meet UK safety standards.
• Turn on your phone's battery protection features, such as Optimised Battery Charging on iPhone or battery protection settings on Android, which reduce time spent at 100%.
• Avoid running the battery to 0% regularly.
• If storing a spare phone, leave the battery around half charged and check it every few months.
• Replace a worn battery promptly rather than running it until it fails.

Wondering whether wireless charging contributes? Our article on whether wireless charging is bad for your battery looks at the heat question in detail.

Can you fix a swollen battery?

No. Swelling is permanent internal damage. There is no safe way to deflate, cool or "recondition" a swollen lithium-ion battery, and advice online to pierce, freeze or press the battery is dangerous. The only fix is to remove the battery and fit a new one, then recycle the old one properly. Once the swollen battery is out, the phone itself is often fine, although the pressure may have damaged the screen, back glass or frame, which may also need replacing.

Replacing a swollen battery: professional or DIY?

Professional repair (recommended for a swollen battery)

Removing a swollen battery is riskier than a routine battery swap, because the cell is already damaged and prying it out can puncture it. A repair shop with the right tools, adhesive removers and a safe workspace is the better option for most people. For iPhones, Apple offers battery service and lists options on its iPhone battery replacement page. Independent repairers are usually quicker and often cheaper; ask what grade of battery they fit and what warranty they give.

DIY replacement

If you are experienced with phone repair, you can replace the battery yourself. Do it only when the swelling is mild and the phone is cool, and take these precautions:

• Work on a non-flammable surface with no flammable materials nearby, and have a metal container ready to put the old battery in.
• Wear eye protection.
• Use plastic opening tools, never metal, near the battery.
• Use the correct adhesive remover or pull tabs rather than levering the battery out.
• If the battery starts to hiss, smoke or heat up, stop, move away and put it in the metal container outdoors if it is safe to do so.
• Fit an OEM standard replacement battery made for your exact model.

You will need the right tools for your phone: opening picks, a suction handle, precision screwdrivers and adhesive. See repair tools and adhesives, and our round-up of professional phone repair tool kits.

Choosing a replacement battery

• Match the battery to your exact phone model and model number.
• Choose an OEM standard battery with the correct capacity and connector.
• Buy from a seller that states its warranty and returns policy.
• Be wary of batteries advertising much higher capacity than the phone was designed for.

Browse replacement phone batteries for iPhone, Samsung, Google Pixel and other models. If your phone is older, compare the cost with a new handset first; our guide to battery replacement vs a new phone works through the decision. iPhone owners deciding when to act can also read what iPhone battery health at 80% means.

How to dispose of a swollen phone battery in the UK

Never put a lithium-ion battery, swollen or not, in your household rubbish or recycling bin. Damaged batteries in bin lorries and waste sites are a known cause of fires. Instead:

1. Tape over the battery's connector with insulating tape if it has been removed, to prevent short circuits.
2. Put it in a non-flammable container, such as a metal tin or a glass jar with a lid that is not airtight, or a small box of sand.
3. Take it to a household waste recycling centre and tell the staff it is a damaged lithium battery, so they can put it in the right place. Many centres have a dedicated battery or small electricals bay.
4. Use a battery collection point. Shops that sell batteries often have collection bins; for a swollen battery, ask staff first rather than dropping it in an open bin.
5. Ask your repairer. If a shop replaces the battery, it should dispose of the old one for you.

Recycle Your Electricals has a battery recycling guide and postcode finder for local drop-off points. The UK's rules on battery collection and recycling are set out by GOV.UK in its guidance on batteries and waste batteries regulations. Do not post a swollen or damaged lithium battery: carriers generally prohibit damaged lithium batteries in the post.

Is it safe to keep using a phone with a swollen battery?

No. Even if the phone still works, the battery is damaged and the swelling can get worse. Continued use and charging increase the risk of overheating, and the pressure can crack the screen or back glass. Replace the battery as soon as you can, and do not charge the phone overnight or leave it unattended while it is charging in the meantime.

Frequently asked questions

How do I know if my phone battery is swollen?

Look for a screen lifting from the frame, a bulging or cracked back, a phone that rocks on a flat surface, a case that no longer fits, or a spongy feel when you press the back gently.

How do I fix a swollen phone battery?

You cannot fix the battery itself. Stop charging, power the phone off and have the battery replaced, ideally by a professional. Then recycle the old battery at a proper collection point.

How do I stop my phone battery swelling?

Once it has started, it cannot be reversed. To prevent swelling in future, avoid heat, use reputable chargers, enable battery protection features and replace worn batteries promptly.

How can I prevent phone battery swelling?

Keep the phone cool, charge on a hard surface, avoid regular deep discharges, use safe chargers and cables, and replace the battery when its health drops significantly.

How do I dispose of a swollen phone battery?

Never put it in household waste. Tape the connector, keep it in a non-flammable container and take it to a household waste recycling centre or battery collection point, telling staff it is damaged.

Is a swollen phone battery dangerous?

It is a sign of internal damage and carries a higher risk of overheating, especially if punctured or charged. Handle it carefully, stop charging and replace it promptly.

How much does a phone battery replacement cost?

It depends on the phone model and whether you use a repair shop or replace it yourself. Swollen batteries may also have damaged the screen or back panel, which adds to the cost. Get a quote for your exact model before committing.

The bottom line

A swollen battery is a safety issue, not just an inconvenience. Stop charging, power off, keep the phone away from heat and flammable materials, and never press or puncture it. Have the battery replaced, by a professional unless you are experienced, and recycle the old one properly. If you are replacing it yourself or stocking parts for repairs, choose an OEM standard battery for your exact model from the phone batteries collection and use the right tools for a safe removal.