Can You Bring Lithium-Ion Batteries In A Carry-On?

You’re packing a power bank, a spare laptop battery, and maybe a cordless drill battery for a work trip. The question feels straightforward — can all this go in your carry-on, or does something have to be checked? A lot of travelers assume batteries are fine in checked bags, and that assumption can get you stopped at security or worse, fined.

The honest answer: spare lithium-ion batteries must stay in the cabin. Installed batteries inside a device may be checked if the device is switched off, but loose cells, power banks, and external chargers belong in your carry-on. Here’s exactly how the TSA and FAA rules work.

The Core Rule: Carry-On Only for Spare Batteries

The Federal Aviation Administration (FAA) and TSA agree on one thing: loose lithium-ion batteries are not allowed in checked luggage. That includes power banks, portable phone chargers, loose 18650 cells, and any battery not currently inside a device.

The reason is safety. Lithium batteries can overheat, vent, or catch fire if damaged or short-circuited. In an aircraft cargo hold, a fire is much harder to detect and fight. By keeping spare batteries in the cabin, flight crew can respond quickly if a battery starts smoking or overheating.

Batteries installed inside a device — like a laptop, tablet, or camera — are generally fine in either carry-on or checked baggage, provided the device is turned off and packed so it cannot turn on accidentally. This is the big distinction most travelers miss.

Why the Confusion? Installed vs. Spare Batteries

Many people read “lithium batteries allowed” and think every battery in their bag is fine. The catch is that “spare” and “installed” are treated very differently. A spare battery is any loose, uninstalled power source — that includes power banks, external chargers, and spare tool batteries. These must go in the cabin.

• Power banks and portable chargers: Always carry-on only. TSA explicitly lists these as prohibited in checked luggage. A typical 20,000 mAh power bank (about 74 Wh) is allowed without special approval.
• Laptop and tablet batteries: If the battery is built in, the whole device can go in a checked bag as long as it’s off. If the battery is removable and you pack it separately, that loose battery becomes a spare and must be in carry-on.
• E-cigarettes and vapes: Must be in carry-on only. Devices containing lithium-ion batteries cannot be checked and must not be charged onboard the aircraft.
• Power tool batteries (18V/20V): Most under 100 Wh are fine in carry-on. Batteries rated 101–160 Wh require airline approval, and anything over 160 Wh is banned entirely.

This distinction catches a lot of travelers who assume that because their laptop with a removable battery can be checked, they can pack the spare battery in the same bag. That spare battery is a safety item and must stay with you in the cabin.

Watt-Hour Limits: What’s Allowed Without Approval

Not all lithium-ion batteries are treated equally. The key number is the watt-hour (Wh) rating, which measures the battery’s energy capacity. Most consumer batteries fall under 100 Wh, which is the threshold for automatic carry-on approval. Batteries between 101 and 160 Wh may be allowed with airline approval, and anything above 160 Wh is banned from all passenger aircraft.

According to the FAA’s PackSafe guide, the rules for carry-on are straightforward: batteries under 100 Wh need no special approval, you can carry two batteries between 101–160 Wh with airline permission, and over 160 Wh is a hard no. The detailed breakdown is available on the installed batteries allowed in checked page at FAA.gov, which covers all the nuances for devices and loose cells.

For the 101–160 Wh tier, you need to contact the airline in advance. Not all carriers will approve these, and even if they do, the batteries must be individually protected to prevent short circuits.

Watt-hour ratings are usually printed on the battery label. If the rating isn’t listed and you can’t calculate it from voltage and amp-hours, assume the battery is in the lower category and pack it in carry-on with terminals protected.

How to Pack Spare Batteries Safely

Simply tossing loose batteries into a bag is a bad idea — loose metal contacts can short against coins, keys, or other batteries, which can cause overheating or even a fire. The FAA requires that spare batteries be individually protected from short circuits.

1. Keep batteries in original retail packaging if you still have it. The packaging is designed to prevent terminal contact.
2. Tape over the terminals with electrical tape or the small stickers often included with new batteries. Covering the positive and negative contacts eliminates the short-circuit risk.
3. Place each battery in a separate plastic bag or protective pouch. Ziploc bags work, but dedicated battery cases are more durable and less likely to tear.
4. Keep spare batteries within reach during the flight. Store them in your personal item or seat pocket rather than overhead bins, so crew can access them if needed.
5. Do not charge devices or batteries onboard. Most airlines prohibit recharging lithium-ion batteries during the flight, even if you have a power bank handy.

These steps are simple and take less than a minute at packing time. They also help you pass through security faster because your bag looks organized and compliant.

Special Cases: Power Tools, Mobility Devices, and Vapes

Certain items have their own quirks. Power tool batteries are common for tradespeople traveling with cordless drills or saws. Most 18V and 20V tool batteries fall under 100 Wh and are fine in carry-on. If you have a larger 60V battery, check the watt-hour rating — those can easily exceed 100 Wh and require airline approval.

For mobility devices with non-removable lithium-ion batteries, TSA has specific guidance. If the battery is removable, take it out and carry it in your carry-on with terminals protected. If the battery is non-removable, the device may not be accepted as checked baggage — check with your airline before traveling. The TSA’s search tool provides detailed rules; the two spare batteries 101-160 Wh page at TSA.gov is the best place to verify any borderline item.

E-cigarettes and vaping devices are always carry-on only. They must not be used or charged during the flight. International flights follow the same IATA-based rules, so the carry-on requirement applies worldwide with very few exceptions. If you’re flying from the US to Europe or Asia, the same watt-hour limits and terminal protection rules apply.

The Bottom Line

Lithium-ion battery rules boil down to one easy check: if the battery is loose or a power bank, it goes in your carry-on. If it’s permanently installed inside a device, it can be checked as long as the device is off. Watt-hour ratings matter only for larger batteries, and damaged or swollen batteries must never fly at all.

To stay safe, pack spare batteries with terminals taped or bagged, keep them within reach, and confirm any 101–160 Wh batteries with your airline before you get to the airport — a quick call to your carrier’s customer service can save you a last-minute hassle at security.