Every airline rule about mobility batteries comes down to one number: watt-hours. Almost no battery label prints it. This page does the conversion, rules on each US carrier, and then explains what actually happens with that number at the airport.

Where to find the numbers on your battery

The label you need is on the battery pack itself, not on the scooter frame and not in the manual. On most travel scooters and folding power chairs the pack sits under the seat or behind the seat post, and the label faces you once the pack is out.

You are looking for two figures printed near each other:

• Voltage — written as V, DC, or "nominal". Travel devices are usually 24 V or 25.2 V. These are the same battery: 24 V is the marketing number, 25.2 V is the true nominal rating of a seven-cell lithium pack, and 25.2 is the one the airline arithmetic uses.
• Amp-hours — written as Ah, occasionally as mAh. If it says 10,400 mAh, that is 10.4 Ah. Divide by 1,000.

Some packs print the watt-hour figure outright, usually as Wh beside the other two. If yours does, you are done — that is the number, and you do not need to calculate anything.

If the label only shows amp-hours

This is the common case, and it is where people guess wrong. Amp-hours alone tell an airline nothing, because a 10 Ah pack at 24 V and a 10 Ah pack at 48 V hold completely different amounts of energy. Only the two multiplied together produce a figure anyone can rule on.

If the voltage genuinely is not printed anywhere on the pack, check the charger. Chargers are labelled with their output voltage, and it will be slightly higher than the battery's nominal rating — a 29.4 V charger belongs to a 25.2 V battery. Use the battery's nominal figure for the calculation, not the charger's output.

What the gate agent actually checks

Not your paperwork, and not your booking notes. The agent looks at the printed label on the pack and compares it to a number they have been given. That is the whole interaction, and it is why a legible label matters more than any documentation you bring.

Three things make it go smoothly:

• The label is readable. If it has worn off, replace the pack or get the manufacturer to send a spec sheet with the serial number on it. A faded label is treated as an unknown battery.
• The pack comes out without tools. Several carriers require the battery to be removable by hand. A pack that needs a screwdriver can be refused even when the watt-hours are fine.
• The terminals are protected. Once the battery is out, the contacts must be covered — a manufacturer's case, or tape over the terminals. A loose pack in a bag is a refusal.

One battery or two — the rule that catches people out

This trips up more travellers than the main limit does. A single installed battery can generally be up to 300 watt-hours. But the moment you carry a spare, several carriers switch to a different rule: two batteries are allowed only if each one is 160 watt-hours or less.

So a 262 Wh pack flies without question on its own. Two 262 Wh packs do not, on Alaska, Hawaiian, Southwest or JetBlue. If you need more range than one battery gives you, the answer is usually to charge overnight rather than to carry a second pack — or to check with that specific carrier in writing before you book.

Use the "batteries carried" selector above to see how the verdicts change.

If your battery is over the limit

There is no appeal at the gate, and there is no fee that makes it acceptable — an over-limit lithium pack is a cargo safety rule, not a baggage policy. The device may still fly if the battery can be removed and left behind, but you then arrive without a working scooter.

Realistically the options are to rent a compliant device at your destination, ship the scooter ahead by ground, or travel with a device built to sit under the ceiling in the first place. Most purpose-built travel scooters and folding chairs are designed around the 300 Wh figure rather than against it — the ZiiLIF R3b runs 262 Wh in a 3.5 lb pack, and the ZiiLIF X runs 252 Wh, both with the watt-hour figure printed on the pack so screening takes seconds.

What this tool is and is not

It reproduces each carrier's published policy as verified in early September 2026, and it does the arithmetic. It is not a guarantee of carriage. Airlines change these rules without notice, international carriers differ from US ones, and an individual agent can ask for something the published policy does not mention.

Treat a green verdict as "your battery is within the published rule", then confirm with your airline when you book. If you want the reasoning behind each carrier's position, the full comparison is in Mobility Scooter Airline Rules 2026, and the watt-hour rule itself is explained in Mobility Scooter Battery Watt-Hours.