Why can’t you pack lithium batteries in checked bags?
A damaged or overheating lithium battery can catch fire. In the cabin, the crew can spot it and put it out; in the cargo hold, no one would see it. So spare batteries and power banks go in your carry-on.
Quick Answer
Lithium-ion batteries can overheat and slide into “thermal runaway,” a chain reaction that can produce intense heat, smoke and fire, sometimes with no warning. It can start if a battery is damaged, overheated, overcharged, exposed to water or packed carelessly. In the cabin, flight attendants are trained to spot and fight these fires quickly. In the cargo hold, a fire could burn unseen. That’s why the FAA requires spare lithium batteries, including power banks and phone charging cases, to be in carry-on bags only, and recommends keeping devices with batteries in your carry-on too. Batteries up to 100 watt-hours are allowed; 101 to 160 need airline approval, with a limit of two spares; bigger ones are forbidden. The FAA verified 89 lithium battery incidents on planes in 2024, a record and more than one a week. Some airlines now go further: since October 2025, Emirates doesn’t allow power banks to be used on board at all.
By the Numbers
Key Facts
- The rule
- Spare lithium batteries and power banks go in carry-on bags only
- The danger
- “Thermal runaway,” a chain reaction that can cause smoke and fire
- Why the cabin
- Crew can spot and fight a battery fire there
- Size limits
- Up to 100 Wh allowed; 101–160 Wh need airline approval; over 160 Wh forbidden
Carry-on vs. checked bag
| Carry-on | Checked bag | |
|---|---|---|
| Spare batteries and power banks | Allowed (within size limits) | Not allowed |
| Phones, laptops and other devices | Recommended | Allowed if fully off and protected, but carry-on is better |
| If a battery overheats | Crew can respond quickly | Could burn unseen |
Airline rules can be stricter than the FAA’s. Check with your airline before you fly.
What thermal runaway is
A lithium-ion battery stores a lot of energy in a small space. If it’s damaged, overheated or short-circuited, one cell can heat up enough to trigger the next, and the heat builds on itself. That chain reaction, called thermal runaway, can produce intense heat, smoke and flames, sometimes with no warning.
Why the cabin is safer
Flight crews are trained to recognize and handle lithium battery fires, and they have equipment to do it. In the cabin, someone usually notices smoke or heat right away. A battery in a checked bag is out of sight in the cargo hold, where a fire could spread before anyone knew.
Airlines are tightening up
Incidents keep rising as people carry more devices. Since October 1, 2025, Emirates has banned using power banks on board, though passengers can still carry one. Southwest Airlines requires power banks to be visible while in use, and several Asian airlines have banned in-flight use too.
Myth vs. Fact
MythA power bank is fine in a checked bag if it’s turned off.
FactSpare batteries and power banks aren’t allowed in checked bags at all. They go in your carry-on.
MythBattery fires only happen with cheap batteries.
FactAny lithium-ion battery can overheat if it’s damaged, overheated, overcharged or short-circuited.
The Bottom Line
Lithium batteries can catch fire, and a fire in the cabin can be spotted and put out. That’s why spare batteries and power banks must travel in your carry-on, never your checked bag.