That old smartphone buried in your junk drawer might be doing more than collecting dust. If its back panel is bulging, its screen is lifting away from the frame, or the case feels unusually warm, the lithium-ion battery inside has likely begun to swell, a chemical breakdown that the U.S. Environmental Protection Agency and fire safety officials say can lead to fires, toxic fumes, and serious injury. As of May 2026, no single federal program tracks how many forgotten phones end up causing household fires, but the agencies responsible for battery safety all agree on one point: a swollen battery is not a dead battery. It is an active hazard.
Why swollen batteries are dangerous
Lithium-ion cells power nearly every portable device in modern life, from phones and laptops to e-bikes and portable chargers. When these cells age, overheat, or sustain damage, gases can build up inside the sealed pouch, causing it to expand. That expansion signals that the internal structure separating the battery’s reactive chemicals has begun to fail.
Once that barrier is compromised, the battery can enter a process called thermal runaway: a rapid, self-sustaining increase in temperature that can produce flames, release toxic fluoride gases, and ignite nearby materials. The Pipeline and Hazardous Materials Safety Administration identifies short circuits, physical damage, and manufacturing defects as conditions that can cause lithium batteries to overheat or ignite. A visibly swollen cell has already crossed into that higher-risk territory.
The EPA classifies many compromised lithium-ion batteries as ignitable or reactive waste under Resource Conservation and Recovery Act codes D001 and D003, which means they can require the same careful handling protocols applied to other hazardous materials at waste facilities.
The scale of the problem
Recalls and fire reports offer a window into how often lithium-ion batteries fail. In 2024, the U.S. Consumer Product Safety Commission and Baseus recalled roughly 429,000 portable chargers after reports of units overheating, expanding, and catching fire, with consumer injuries reported, according to Associated Press coverage of the recall. Separately, the CPSC warned consumers to stop using Unit Pack Power e-bike batteries due to fire and burn hazards, citing risk of serious injury and death.
The Fire Department of the City of New York has flagged lithium-ion battery incidents as a growing concern, stating that improper storage, charging, or disposal of these batteries can cause serious property damage, injury, or death. Tennessee’s Department of Environment and Conservation advises anyone who discovers a bulging or overheating battery to move it away from flammable materials and set it on a non-combustible surface immediately.
What the data does not yet show is how many of these incidents trace specifically to old smartphones rather than e-bikes, scooters, or power tools. Neither the EPA nor PHMSA has published granular breakdowns isolating phones as a fire source. Whether that gap reflects low incidence or simply incomplete tracking is unclear, but the underlying chemistry is identical across device types: a failing lithium-ion cell in a phone can ignite just as readily as one in a hoverboard.
How to spot a swollen battery
Not every swollen battery announces itself with a dramatic bulge. Early signs can be subtle. On phones with glass or plastic backs, look for the rear panel separating slightly from the frame or a faint rocking motion when the phone is placed on a flat surface. On older models with removable backs, the cover may no longer snap flush. A screen that appears to push outward from one corner, a phone that no longer sits flat, or a case that feels tight and warm are all warning signs.
If a device emits a sweet or chemical odor, produces visible smoke, or feels hot without being plugged in, treat it as an immediate hazard. Do not attempt to charge it, and do not press on the swollen area.
Safe storage until you can recycle
The EPA’s guidance on lithium battery safety and recommendations from fire departments converge on a few clear steps for the period between discovering a swollen battery and getting it to a proper facility:
- Isolate the device. Place it on a hard, non-combustible surface such as a concrete floor, ceramic tile, or metal tray. Keep it away from paper, fabric, bedding, and cleaning products.
- Do not charge or power on the device. Sending current through a compromised cell increases the risk of thermal runaway.
- Tape exposed terminals. If the battery is removable, cover the metal contacts with non-conductive tape (electrical tape or heavy packing tape) to prevent short circuits. The EPA emphasizes this step in its advice on sending used batteries to proper recyclers.
- Bag it individually. Place the phone or loose battery in a clear plastic bag by itself so it cannot contact metal objects, keys, coins, or other batteries that could bridge the terminals.
- Do not puncture, crush, or attempt to “deflate” the battery. Piercing the casing can trigger the very reaction you are trying to prevent.
- Store in a cool, dry area. Avoid garages that reach high temperatures in summer or locations near heat sources.
Where to recycle a swollen phone
Getting rid of the device safely is the part where many people get stuck, and where the gap between federal guidance and everyday convenience is widest.
Household trash and curbside recycling are off-limits. Every agency reviewed for this article agrees: compactors and sorting equipment at waste facilities can crush or pierce a lithium cell, creating sparks that ignite surrounding material. The EPA explicitly warns consumers not to place lithium-ion batteries in regular trash or curbside bins.
Municipal household hazardous waste (HHW) programs are often the most reliable option. Many cities and counties operate permanent drop-off centers or periodic collection events designed to handle batteries, paint, solvents, and other materials that require special processing. Check your local government’s waste authority website or call 311 for schedules and locations.
Certified electronics recyclers that follow EPA and PHMSA handling rules accept smartphones and loose lithium-ion batteries. The Call2Recycle locator can help you find participating drop-off sites, which include many Best Buy, Home Depot, and Staples locations. However, these retail collection bins are designed primarily for intact, undamaged batteries.
Use caution with retail drop boxes for swollen cells. The CPSC, in its warning about defective e-bike batteries, specifically cautioned against using standard retail collection bins for damaged or defective batteries, noting they require more controlled handling. If your phone is visibly bulging, hot, or has emitted smoke or odor, contact your local waste authority or fire department for specific instructions rather than relying on an unattended collection box.
Shipping a swollen phone to a manufacturer or recycler is not as simple as dropping it in a mailer. PHMSA regulations under 49 CFR 173.185 restrict how damaged lithium batteries can be transported, particularly by air. If a manufacturer offers a mail-back program for a recalled device, follow their packaging instructions exactly. Otherwise, hand-delivering the phone to a local facility is the safer route.
What regulators still need to address
The practical burden right now falls almost entirely on consumers, and the guidance they face is scattered across multiple agencies with no single, plain-language federal protocol for handling a swollen phone at home. PHMSA’s transport rules were written for commercial shippers. The EPA’s hazardous waste framework was built for industrial generators. Municipal programs vary wildly by region. The result is that many people default to the easiest option, tossing the device in the trash, which is exactly what every agency says not to do.
A unified consumer-facing guide from the CPSC or EPA, one that walks a non-expert through identification, safe storage, and local disposal options in plain language, does not yet exist at the federal level. Until it does, the safest approach is to treat any swollen smartphone battery as a serious risk, isolate it from everyday clutter, and move it into the regulated recycling stream as quickly and carefully as your local options allow.
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*This article was researched with the help of AI, with human editors creating the final content.
