Power Banks & Lithium Batteries on Planes

Almost everything confiscated at a security checkpoint is a liquid or a battery. The liquids rule is famous, endlessly explained, and mostly understood. The battery rule is neither — and it is the one that can quietly cost you a charger, delay a bag, or in the worst case start a fire in a cargo hold.

The good news is that it condenses to a single sentence: spare lithium batteries and power banks travel in the cabin, never in a checked bag. Everything below is the detail behind that, including the arithmetic that tells you whether a specific charger is allowed.

The rule in one table

Those thresholds come from the FAA’s PackSafe guidance, and TSA enforces the carry-on-only part at the checkpoint. Note the asymmetry in the middle column: a battery installed in a device— your laptop, your phone, your camera — is treated more leniently than a loose one. It is the spare that is restricted, and a power bank is legally a spare, because its entire purpose is storing charge for something else.

The arithmetic: mAh to watt-hours

Power banks are sold in milliamp-hours; the rules are written in watt-hours. The conversion is one line:

Wh = (mAh ÷ 1,000) × voltage, and the voltage of a lithium-ion cell is 3.7 V unless the case says otherwise.

So, for the sizes people actually own:

• 5,000 mAh → about 18.5 Wh. Fine.
• 10,000 mAh → about 37 Wh. Fine, and the sweet spot for one-bag travel.
• 20,000 mAh → about 74 Wh. Fine, and the largest most people need.
• 26,800 mAh → about 99 Wh. Just under the line, which is exactly why this odd-looking capacity is so common.
• 30,000 mAh → about 111 Wh. Over 100 — airline approval territory.
• 50,000 mAh → about 185 Wh. Forbidden outright.

That 27,000 mAh ceiling is not a coincidence and it is the single most useful thing on this page: 100 Wh ÷ 3.7 V works out at roughly 27,000 mAh, so manufacturers design right up to it and stop. If you are shopping for a travel power bank, anything advertised well above 27,000 mAh is asking you to have a conversation at a gate.

Most modern banks print the Wh figure on the case precisely because of this rule. If yours does, use that number and skip the maths — and if it prints nothing at all, that is a reason to leave it at home rather than to guess, because you cannot show a screener a rating that doesn’t exist.

Why checked bags are the line

The rule looks arbitrary until you consider where a fire can be dealt with. In the cabin, a battery that starts venting is visible within seconds and reachable by crew who are trained and equipped for exactly this. In the hold, it is neither.

That is the whole reasoning, and it has two practical implications people miss. First, if your carry-on gets gate-checked— which happens routinely on full flights and small aircraft — the power bank has to come out and travel with you in the cabin. Second, this is a strong argument for keeping electronics in your personal item rather than your main bag: the personal item goes under the seat and is essentially never taken off you.

Protecting the terminals, and why it matters

The FAA requires that battery terminals be protected from short circuit — the contacts must not be able to touch other metal. A loose battery rattling around a pocket with keys and coins is the specific scenario the rule exists to prevent.

Three acceptable ways to do it: leave the battery in its original retail packaging, tape over the contacts, or keep each one in its own pouch or plastic bag. In practice this is the reason a tech organizerearns its place in a travel kit — not because a pouch is safety equipment, but because it stops the situation the rule is written about from arising at all. A dedicated compartment for each item also makes the checkpoint faster, since you can lift out one pouch instead of excavating a bag.

Airlines can be stricter, and increasingly are

The FAA sets a floor, not a ceiling. Carriers are explicitly permitted to impose tighter quantity and watt-hour limits, and a number of them have added rules of their own about using or charging power banks in flight and about keeping them out of overhead bins.

Because those policies are carrier-specific and have been changing, we are not going to print a list here that would be wrong within a month. The reliable move is the same one we recommend for size and weight rules: open your airline’s own baggage or dangerous-goods page before you fly. It takes half a minute, and it is the only version of the answer that is current for your flight.

If you’re asked to check your bag

This is the situation where the rule most often catches out people who otherwise packed correctly, because it arrives with no warning: the bins are full, the aircraft is small, or your fare put you in the last boarding group, and a crew member takes your carry-on at the door.

At that moment your bag stops being a cabin bag and becomes a checked one — and the power bank inside it is now in a place it is prohibited from being. What to do, in order:

• Say yes, then ask for a moment. Crew deal with this constantly and nobody objects to a passenger retrieving batteries; it is the outcome the rule wants.
• Take out the power bank, spare camera batteries and anything else loose. Devices with batteries installed can stay if you’re comfortable with that; the spares cannot.
• Take your valuables while you’re in there. Passport, medication, laptop, keys. You will not see the bag again until baggage claim.
• Have somewhere to put them. This is the practical argument for keeping a jacket with real pockets, or a small pouch, within reach on boarding day.

The version of this that requires no thinking at all: keep the tech in your personal item from the start. A bag that lives under the seat in front of you is never gate-checked, so the question never comes up.

The mistakes that actually cost people batteries

Every one of these is common, and every one is avoidable in about ten seconds.

Leaving a spare in a checked bag.The single most frequent one, usually a camera battery or a small charger in a side pocket that was forgotten about. Airlines screen for this, and finding one means your bag gets pulled — which at best is a delay and at worst means it travels without you.

Buying on headline capacity.A 30,000 mAh bank looks like better value than a 20,000 mAh one right up to the point where it is over 100 Wh and needs permission you didn’t ask for. Do the arithmetic before you buy, not at the gate.

Owning a bank with nothing printed on it. If a screener asks and the case states no capacity, you have no way to demonstrate it is under the limit. Unbranded banks with blank cases are the ones that get surrendered.

Letting terminals rattle against metal.Loose spares in the same pocket as keys or coins is precisely the short-circuit scenario the FAA’s terminal-protection rule exists to prevent. A pouch or a strip of tape resolves it entirely.

The rest of a travel tech kit

The battery rule is the strict one, but a few adjacent items come up often enough to be worth stating plainly.

Devices with batteries installed— laptop, phone, tablet, camera, e-reader, electric toothbrush — can travel in either bag under the general rules, though there are good reasons beyond regulation to keep anything valuable or fragile in the cabin.

Cables, chargers and plug adapters carry no battery and are unrestricted. They are, however, the items people most often arrive without, which is an organization problem rather than a compliance one.

Smart luggage with a built-in batteryis its own category: many carriers require the battery to be removable, and require you to remove it if the bag is checked. If you own one, that is another line to check on your carrier’s page.

Spare camera batteries follow exactly the same rule as power banks: cabin only, terminals protected. They are small enough that people forget they count, and they are the most common thing found loose in a checked bag.

The short version

• Power banks and spare batteries: carry-on only, never checked.
• Up to 100 Wh (about 27,000 mAh) needs no approval.
• 101–160 Wh needs airline approval, maximum two spares.
• Over 160 Wh is forbidden.
• Protect the terminals — original packaging, tape or a pouch.
• If your bag is gate-checked, take the batteries out first.
• Check your own airline: they are allowed to be stricter, and some are.

Pair this with the liquids rule and you have covered the two categories that account for nearly everything taken off passengers at a checkpoint. Neither rule is hard; both are just badly explained almost everywhere else.