How to Spot a Failing Battery: Swelling, Heat and Other Signs
The warning signs fire agencies list for lithium-ion batteries, why batteries swell, what to do in the first few minutes, and how to tell ordinary wear from a battery you should stop using.
Research-based: public sources and consumer feedback, not hands-on testing. How we review
In this article
Quick answer
Stop using a rechargeable battery if it smells, changes color, gets too hot, changes shape, leaks or makes odd noises. Those are the signs US fire agencies list. A swollen battery in particular is damaged and a potential fire hazard: do not charge it, press on it or try to pry it out. Keep it somewhere safe and away from anything that burns, and contact the manufacturer or your local hazardous waste service.
A battery that is wearing out and a battery that is failing dangerously are different things. This guide explains how to tell them apart, what the official warning signs are, and what to do in the first few minutes after you notice one. It applies to the lithium-ion batteries in phones, laptops, power banks, cordless tools and vacuums, e-bikes and similar products. It sits under our lithium battery safety guide, which covers charging, storage, travel and disposal.
If a battery is smoking, hissing or too hot to touch
Do not try to deal with it yourself. The US Fire Administration’s advice is to get out quickly, and the EPA says to call 911 if you think there is an imminent risk of fire.
Key takeaways
- The official warning signs are odor, a change in color, too much heat, a change in shape, leaking and odd noises
- A swollen battery is damaged and a potential fire hazard, according to the EPA
- Do not press, bend, puncture or pry out a swollen battery
- A battery that simply runs down faster is worn, and is not on the fire agencies' list of danger signs
- Do not put a failing battery in the trash; ask the manufacturer or a hazardous waste site what to do with it
The warning signs
The National Fire Protection Association and the US Fire Administration publish the same list. Stop using a lithium-ion battery if you notice any of these.
| Official sign | What it can look like in practice |
|---|---|
| Change in shape | A phone back or screen lifting away from the frame, a laptop that rocks on a flat desk or whose trackpad has risen, a power bank whose case has bulged or split |
| Too much heat | A device or charger that is uncomfortably hot, especially when it is not doing much |
| Odor | A chemical or burning smell from the device or its charging port |
| Change in color | Scorching, browning or discoloration on the battery, the case or the plug |
| Leaking | Any fluid or residue coming from the battery |
| Odd noises | Hissing, popping or crackling |
The left-hand column is the agencies’ wording. The right-hand column is our own description of how each sign tends to be noticed, added to make the list easier to use; it is not from the agencies, and the absence of these examples does not mean a battery is safe.
Why batteries swell
Dell’s guidance for its laptops is direct about this: the potential for swelling is inherent to lithium-ion polymer battery technology, and batteries can swell for reasons such as age, the number of charge cycles, or exposure to high heat. In other words, swelling is not always a sign that you did something wrong, and it is not confined to cheap products.
It still has to be acted on. The EPA says swelling indicates damage to the battery and is a potential fire hazard, and Dell says a swollen battery should not be used and should be replaced and disposed of properly.
What to do right away
- Stop using it and stop charging it. Unplug the charger.
- Do not put pressure on it. Dell’s handling rules are not to crush, drop, bend or puncture a battery, not to press on its surface, and not to use tools to pry against it.
- Do not force it out. If a battery is stuck in a device because it has swollen, Dell says not to try to free it, because puncturing, bending or crushing it can be dangerous.
- Put it somewhere safe. The EPA’s advice is to store the battery or device in a safe location until you have found the right disposal route, and it gives the example of a bucket filled with a fire suppressant such as sand or cat litter. Keep it away from anything that can burn.
- Get instructions. Contact the manufacturer of the product, the retailer that sold it, or your state or local household hazardous waste program. For its laptops, Dell recommends contacting its support for replacement options, including replacement by an authorized technician.
Dell’s guidance also mentions letting a swollen laptop battery run down by disconnecting the AC adapter. That is advice for its own laptops; for any other product, follow the manufacturer’s instructions.
What not to do
- Do not put it in the trash or the recycling bin. The EPA says lithium-ion batteries can cause fires in transport, at landfills and at recycling plants.
- Do not keep using it “until the replacement arrives”. The agencies’ instruction is to stop.
- Do not leave it in a hot car or in direct sunlight.
- Do not take it on a plane. The FAA’s guidance for passengers has specific rules for damaged and recalled batteries; check its PackSafe page and your airline before you travel.
- Do not fit a cheap replacement in a hurry. See the section on replacements below.
Wear or danger?
| What you notice | What it most likely means |
|---|---|
| The battery runs down faster than it used to | Normal wear. Capacity loss is not on the fire agencies’ list of warning signs. |
| The device is warm while charging or under heavy use | Usually normal. “Too much heat” is the warning sign: hot enough that you would not want to hold it. |
| The device shuts down unexpectedly | Can be an aging battery. Have it checked, and watch for the signs above. |
| Any change in shape, smell, leak or noise | Stop using it. |
This table is our own reading of the agencies’ list, not a diagnostic. If you are unsure which row you are in, treat it as the last one.
Check whether it has been recalled
A battery that overheats may be part of a known problem, and a recall can mean a free replacement or a refund. Search the brand and model on the CPSC site; our recall guide shows how. We keep summaries of power bank recalls, phone charger recalls and e-bike and scooter battery recalls. If yours is not listed and it seems dangerous, report it: see how to report an unsafe product.
Replacing the battery
- Use a genuine or manufacturer-approved replacement. Dell warns that a non-genuine or incompatible battery may increase the risk of fire or explosion. The CPSC has warned about specific aftermarket battery packs, as we note in cordless vacuum problems.
- Check the warranty first. A battery that swells inside the warranty period may be replaced under it. See what an appliance warranty covers.
- Do not reinstall a damaged or swollen battery, which Dell lists among its rules.
Getting rid of it
For an ordinary worn-out battery, the EPA’s instructions are to cover the terminals with non-conductive tape or put each battery in its own plastic bag, and take it to a household hazardous waste site or a battery recycling point. For a swollen or damaged one, ask the manufacturer, retailer or hazardous waste program first, as above.
How we researched this
The warning signs are those published by the National Fire Protection Association and the US Fire Administration. The handling advice comes from the EPA’s guidance on lithium-ion batteries and from Dell’s published guidance on swollen laptop batteries, which we use as one manufacturer’s example. We did not test any battery. The practical descriptions of each sign, and the wear-or-danger table, are our own and are labeled as such.
Frequently Asked Questions
Is a swollen battery dangerous?
The EPA says swelling indicates damage to the battery and is a potential fire hazard. Stop using and charging the device, do not press on or puncture the battery, and contact the manufacturer or a hazardous waste service.
Can I still use my phone if the battery is swollen?
The official advice is to stop. Dell’s guidance for laptops says a swollen battery should not be used and should be replaced and disposed of properly, and fire agencies list a change in shape as a reason to stop using a battery.
Why do lithium batteries swell?
Dell’s guidance gives age, the number of charge cycles and exposure to high heat as reasons, and describes the potential for swelling as inherent to lithium-ion polymer batteries.
How do I dispose of a swollen battery?
Do not put it in the trash. The EPA advises storing it somewhere safe, for example in a bucket of sand or cat litter, and contacting the manufacturer, the retailer or your local household hazardous waste program.
Is a battery that drains quickly dangerous?
Faster draining on its own is normal wear and is not among the fire agencies’ warning signs. Heat, smell, swelling, leaking or noise are.
Sources & Evidence
Where the facts in this article come from. Summaries are in our own words; follow the links to check them yourself.
More on: Electronics Product Safety & Recalls
