Signs of a Failing or Swollen Smartwatch Battery and What to Do

Why smartwatch batteries swell

Smartwatches use lithium-ion or lithium-polymer cells. These cells store energy through chemical reactions that are meant to stay stable over hundreds of charge cycles. When a cell is damaged, overcharged, exposed to extreme heat, or simply reaches the end of its design life, those reactions can become unbalanced. One result is the buildup of gas inside the sealed battery pouch.

The gas increases pressure inside the battery. The battery pouch is flexible, so it expands. Inside the tight case of a smartwatch, that expansion has nowhere to go, so it pushes against the screen, the back plate, and the case walls. As the pressure grows, you will see physical changes on the outside of the watch.

Battery swelling is not a software problem. It does not show up as a warning on the display or in the battery health menu. It is a physical change that you need to spot by looking at and feeling the watch.

The watch itself may still power on and work normally for a while after swelling begins. That makes it easy to ignore. Do not ignore it. A swollen battery is a safety issue, not just a cosmetic one.

Warning signs to look for

Check your watch regularly, especially if it is a few years old or has been exposed to heat. Look at the watch from the side, not just from the front. Hold it up to light and see if the gap between the screen and the case is even all around.

• A display that lifts away from the case, creating a visible gap or a screen that rocks when you press on it
• A back case that bulges outward or no longer sits flat against your wrist
• A case seam that has opened up along the side, sometimes with a hairline gap
• The watch band no longer fits snugly against the case because the case has changed shape
• The screen or back panel looks like it is being pushed outward from inside
• The watch becomes harder to press, or the buttons feel stiff because the internal components have shifted
• The watch case creaks or moves slightly when you apply gentle pressure

Why you should stop using the watch immediately

A swollen battery is under pressure. The outer casing of the battery is meant to contain the cell's materials, but it is not designed to hold gas forever. If the pressure gets high enough, the casing can rupture.

When a lithium-ion battery ruptures, it can release flammable electrolyte and heat. It can also catch fire, especially if the battery is being charged while it fails. Charging increases the temperature and the chemical activity inside the cell, so a swollen battery that is plugged in is more dangerous than one sitting idle.

Wearing a swollen watch is also risky. The back case may press against your skin with an uneven surface, and if the battery ruptures while on your wrist, it can cause burns.

There is also the risk of damaging the watch beyond repair. The pressure inside the case can push against the display, cracking it, or against the internal circuit board, breaking connections. The sooner you stop using the watch, the better the chance that a repair shop can recover the components and transfer your data.

What to do right now

The steps are simple and you should follow them in order.

Stop wearing the watch, turn it off if it is on, and do not charge it. Do not plug it into a charger, a computer, or any other power source.

Do not press on the swollen area, do not bend the watch, and do not try to pop the screen back into place. Puncturing the battery can cause it to vent or ignite.

Place the watch in a cool, dry location away from flammable materials. A metal container or a ceramic bowl is better than a plastic bag. Do not leave it in a hot car or near a radiator.

Contact the manufacturer or the retailer where you bought it. Many smartwatch makers have a warranty or a battery replacement program. Even if the warranty has expired, the manufacturer may have a safety recall or a trade-in process.

If you cannot reach the manufacturer, look for a professional electronics repair service. Search for one that advertises battery replacement for smartwatches. Tell them the watch has a swollen battery and that you need them to handle it safely.

Do not throw the watch in the regular trash. E-waste rules in many regions require that lithium batteries be recycled or disposed of at a collection point. Your local waste authority likely has a designated drop-off location.

If the watch is beyond repair, consider a replacement from our list of reliable budget options.

Can a swollen battery be fixed?

In most cases, a smartwatch with a swollen battery can be repaired by replacing the battery, provided the rest of the watch is intact. The repair technician opens the case, removes the swollen cell, and installs a new one. That is a job for a professional, not something you should attempt at home.

If the battery has been swollen for a long time and has pushed hard against the screen, the display may be damaged. In that case, you might need a screen replacement as well.

Some smartwatches are not designed to be opened, and the case may be sealed with adhesive. A good repair shop has the right tools and experience. If the watch is still under warranty, the manufacturer will usually replace the entire unit rather than repairing it.

The cost of repair is not something we can quote here. It depends on the brand, the model, and whether the screen needs replacing. Before you pay for a repair, ask the shop if they will transfer your data or if the watch will need to be reset.

How to reduce the risk of battery swelling

You cannot prevent all battery failures. Some cells develop internal defects even with careful use. But you can lower the risk with good habits.

Avoid exposing your watch to extreme heat. Do not leave it in a parked car, on a windowsill, or under a direct lamp while charging. Heat accelerates the chemical aging of lithium cells.

Use the charger that came with the watch, or one that is certified for your model. A charger that delivers the wrong voltage or current can overstress the battery.

Do not let the battery drain to zero and stay there for weeks. Lithium cells prefer to be stored at around a partial charge, not fully empty or fully full for a long time.

If you notice the watch getting noticeably hot while charging or during a workout, stop using it and let it cool down. Repeated high temperatures can shorten battery life.

Follow the manufacturer's guidance on battery health. Many smartwatches have a battery health menu that tells you the maximum capacity of the cell. If the capacity has dropped well below the original, consider a battery replacement before you see swelling. For more on battery health tracking, see our article on smartwatch battery health percentage.

When it is not battery swelling

Not every gap or creak means a swollen battery. A screen can lift because the adhesive that holds it has weakened over time, especially in high heat. A band can pull on the case and make the seam look uneven. If the watch has been dropped, the case may be slightly bent.

The difference is usually visible when you compare the two sides of the watch. Battery swelling creates a uniform outward push, so the gap looks even all around, or the back bulges in a regular curve. Impact damage often looks uneven and can be traced to a specific corner or edge.

If you are not sure, do not risk it. Treat an unexplained gap as a swollen battery until a professional tells you otherwise. The cost of a checkup is lower than the risk of a rupture.

You can also compare the behavior of the watch. If the battery health percentage in the settings has dropped sharply, and you see a physical gap, the two together point to a battery issue.

What this means for buying your next smartwatch

Battery swelling can happen to any brand, but how a company handles it matters. Look for a manufacturer that offers a warranty of at least one year and a clear battery replacement policy. Some brands let you pay for a new battery after the warranty ends.

If you are buying a used smartwatch, ask the seller about the battery health and whether the watch has ever been opened. You can also ask for a photo of the watch from the side. A used watch with a cracked screen or a loose back panel may be hiding a battery problem.

For new buyers, the guide to best smartwatches under 100 can help you find a budget-friendly option, but consider spending a bit more for a brand that supports repairs. The guide to best certified brands smartwatches lists brands that meet certain reliability standards.

If you already own a watch and want to know how long it will last before battery issues become likely, read our article on smartwatch battery degradation years.

And if you are planning to keep the watch for several years, check whether the manufacturer sells replacement batteries or offers a repair service. That information is not always in the product listing; you may need to contact support.

What to do depending on your situation

Questions

Can a swollen smartwatch battery explode?

It is rare, but a ruptured lithium battery can release heat and catch fire. The risk increases while charging. That is why you should stop using and stop charging a swollen watch immediately.

Will the watch still work if the battery is swollen?

It may continue to power on and function for a while, because the electrical contacts are still intact. But the pressure is damaging the watch internally, so you should not rely on it.

Can I fix a swollen battery myself?

No. Opening a smartwatch and removing a swollen battery requires special tools and experience. The battery can rupture if punctured or bent. Always use a professional repair service.

How long does a smartwatch battery last before swelling?

Battery swelling is not on a fixed schedule. It depends on charge cycles, heat exposure, and the quality of the cell. Some batteries last years without swelling; others develop issues early. There is no way to predict it with certainty.

Does the battery health percentage show swelling?

No. Battery health percentage measures capacity, not physical integrity. A watch can show 100% health and still have a swelling battery, or show low health without swelling.

What should I do with a swollen smartwatch if the manufacturer won't help?

Take it to an electronics recycler that handles lithium batteries, or look for a local repair shop that accepts old devices. Never dispose of it in household trash.