Free CPAP tool
FAA CPAP Battery Watt-Hour Check
Airlines judge lithium-ion batteries by watt-hours, but many CPAP batteries only print mAh and volts. Enter both and you get the Wh rating and the FAA category: up to 100 Wh allowed, 101 to 160 Wh with airline approval, over 160 Wh forbidden on passenger aircraft.
Formula
Wh = mAh x V / 1000. The FAA's own tip is to multiply the battery voltage by the amp-hours; dividing mAh by 1000 gives amp-hours.
Category mapping: 0 means 100 Wh or less, allowed in carry-on. 1 means more than 100 and up to 160 Wh, which needs approval from the airline, with a limit of two spare batteries per person. 2 means more than 160 Wh, forbidden on passenger aircraft. Spare lithium batteries must go in carry-on baggage with the terminals protected from short circuit.
Worked example
A 10,000 mAh battery at 14.4 V: 10,000 x 14.4 / 1000 = 144 Wh. That is above 100 and not above 160, so the category is 1: ask your airline for approval before you fly, and carry no more than two such spares. A 6,600 mAh battery at 14.4 V gives 95.04 Wh, category 0.
Assumptions and limits
- Use the nominal voltage printed on the battery, not the charger voltage.
- If the battery label already shows Wh, use that figure directly; it is what the airline checks.
- Airlines and other countries may set stricter limits than the FAA.
Supplies that can help
A battery pack that runs a CPAP machine without mains power, for camping, power outages or long flights.
A padded bag that protects the machine, mask, tubing and power supply in transit.
A cord or converter that runs a CPAP from a 12 V or 24 V DC source, such as a car outlet, RV or deep cycle …
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Frequently asked questions
How do I convert mAh to Wh for a CPAP battery?
Multiply mAh by the nominal voltage and divide by 1000. A 10,000 mAh pack at 14.4 V is 144 Wh. If the label lists Wh, trust the label.
Can I bring a 160 Wh CPAP battery on a plane?
The FAA allows lithium-ion batteries of 101 to 160 Wh only with airline approval, and limits spares in that range to two per person. Above 160 Wh is forbidden on passenger aircraft. Call the airline before you fly, since some are stricter.
Do CPAP batteries have to go in carry-on?
Spare lithium batteries, including power banks, must be in carry-on baggage with their terminals protected. A battery installed in a device follows the device rules. Keep the battery in its case or tape the terminals.
Sources
Last reviewed October 11, 2026. How we research · Report an error