A swollen power bank points to gas buildup from heat, overcharge, age, or damage—stop using it and move it to a safe, ventilated spot.
You picked up your charger and noticed a bulge, a split seam, or a case that no longer sits flat. That puffed shape is a warning. Lithium-ion cells can generate gas when stressed, and that gas pushes the pack outward. The good news: you can act fast, stay safe, and decide whether repair, replacement, or disposal is the right move.
What Swelling Tells You
Portable chargers use lithium-ion pouch or prismatic cells sealed in a tight shell. When those cells run into heat, overcharge, deep aging, or physical harm, side reactions create gas. That gas has nowhere to go, so the case bows outward. You might see gaps at the seams, a wavy surface, or buttons that stick. Treat that bulge as a stop sign.
Quick Pattern Guide
| Likely Cause | What You’ll See | What To Do Now |
|---|---|---|
| Hot charging area or sun exposure | Case softens, odor, warm shell | Unplug, cool in open air |
| Overcharge or cheap charger | Fast puffing during a charge | Unplug, isolate the pack |
| Age and heavy cycles | Slow bowing over weeks | Plan for replacement |
| Deep discharge or storage at 0% | Won’t hold charge, then swells | Retire the unit |
| Drop or crush damage | Dents, cracked plastic | Stop use, recycle safely |
| Defect or recall | Sudden bulge, brand notices | Check recall page |
Power Bank Swollen: Common Causes And Fixes
Heat From Charging Or Storage
High cell temperature speeds up side reactions inside the pack. Leaving a charger in a car, on a blanket, or near a heater traps heat. Repeated heat cycles age the pack and can kick off gas production. Move charging to a firm, open surface and keep it away from bedding and direct sun.
Overcharge Or Poor Charging Control
Good packs include protection chips that stop charge at the right voltage. Low-quality boards can drift or fail. Matching a fast-charge brick that overshoots spec can also stress cells. If swelling began during a charge session, retire the charger and use a known-good wall adapter for other devices. For background on why bulging is a red flag, see these battery safety tips.
Calendar Aging And Heavy Use
Cells age from time as well as cycles. The solid-electrolyte interface grows, the electrolyte breaks down, and gas builds in tiny pockets. If your pack is a few years old and capacity has dipped, swelling is a sign it’s at the end of its service life.
Deep Discharge Or Storing Empty
Letting a pack sit near zero can trigger copper dissolution and other cell damage. When you later charge it, those damaged spots can react and form gas. Keep long-term storage near half charge to lower stress.
Physical Damage Or Manufacturing Faults
A drop, crush, or puncture can short layers inside the pouch. In rare cases a design or assembly fault shows up months later. If your model shows up in a recall, stop use right away and follow the maker’s directions for a refund or swap—see this recent CPSC warning as a reminder to check your brand and batch.
Safety Steps Right Now
Move from “why” to “what now.” Here’s a safe, practical sequence you can follow immediately.
- Unplug the unit and power it down. Avoid pressing on the bulge.
- Place it on a non-flammable surface in a ventilated spot—tile, concrete, or a metal tray.
- Keep it away from paper, bedding, or anything that could catch fire.
- Do not charge it again to “test.” Swollen packs can vent or ignite under stress.
- If you must move it, use tongs or thick gloves and keep your face away.
- Do not pierce the case to “let the gas out.” That can cause fire or toxic fumes.
- Plan the next step: recycle, claim a recall, or replace the unit.
How Storage, Charging, And Use Affect Risk
Good habits lower stress inside the cells. Small changes go a long way: cooler charging, gentler state of charge, and clean cables all help. Use the table below as a quick habit guide.
| Habit | Risk Level | Why It Helps |
|---|---|---|
| Charge on a hard, open surface | Low | Heat can escape |
| Stop near 80–90% for daily use | Low | Less voltage stress |
| Store near 40–60% charge | Low | Reduces aging reactions |
| Use the cable that came with it | Medium | Matches charge profile |
| Avoid cars or hot windowsills | Medium | Prevents heat soak |
| Retire packs after 2–4 years | Medium | Aging speeds up later |
| Ignore bulges or odd smells | High | Raises fire risk |
| Keep charging while covered | High | Traps heat |
| Use no-name fast-charge bricks | High | Can overshoot spec |
When Replacement Makes Sense
Any visible bulge calls for retirement. Some compact packs can be opened and the cells swapped by a service shop, but most sealed power bricks are not worth the labor. If your unit is under warranty, start a ticket with the brand. If it is part of a recall, stop use and follow the claim steps for a refund or safe replacement.
Disposal And Recycling Without Drama
Do not bin a swollen charger. Local waste streams can catch fire when a lithium-ion pack gets crushed. Many cities run drop-off sites or retail take-back bins for damaged cells. Tape the terminals, place the unit in a clear bag, and carry it to a battery collection point or a household hazardous waste site. If you ship anything, follow carrier rules for damaged cells and label the package.
Buying A Safer Model Next Time
Pick brands that publish cell chemistry, protection features, and certifications. Look for independent listing marks and clear specs for input and output. Prefer models with thermal cutoffs, separate charge and discharge paths, and honest capacity ratings. Match the charger and cable to the power bank’s stated limits. A pack that runs cool under load usually points to sane design.
Simple Checks Before Every Trip
Give your charger a five-second scan before you toss it in a bag. Look for swelling, cracked seams, warped ports, dark marks, or a sweet solvent smell. If anything looks off, leave it behind and plan a replacement. During travel, keep lithium-ion packs in carry-on so you can watch for warning signs and respond quickly.
Frequently Asked Signs You Can Trust
Visual And Smell Clues
Gap at the seam, warped shell, buttons that stick, or a sweet-chemical odor all suggest gas inside. A hissing sound or smoke means step back and clear the area.
Performance Clues
Shrinking run time, slow charging, heat during light use, or sudden shutdowns imply aging cells. Pair those with even a slight bulge and it’s time to retire the pack.
Quick Takeaway And Next Steps
Swelling means the pack is stressed and unsafe. Stop charging, isolate it, and plan for recycling or a warranty claim. Set better charging habits, store around half charge, and pick a listed, well-built unit next time. That simple routine keeps your gear powered and your space safe.