CPAP Battery Calculator
How long will a battery run your CPAP? Pick your machine, pressure, humidifier and battery for an estimate built on ResMed's own power figures, plus FAA travel rules.
Your setup
ResMed has not published battery figures for the AirSense 11, so this uses ResMed's AirSense 10 figures. Treat it as a rough estimate.
On an auto machine, ResMed uses the 95th percentile pressure; CPAP Clarity shows yours on the dashboard after you import your SD card. Between two steps, pick the higher one.
Humidifier and tube
Lithium-ion CPAP battery, 24 V output. Needs Medistrom's AirSense 11 kit (P24R11PLK), sold separately.
Estimated runtime
7.2hours
About 1.0 nights of 7.5 hours on one charge. An estimate, not a promise: pressure, leak, cold and battery age all move it.
Carry-on only. 100Wh or less, so the FAA does not require airline approval. Under FAA rules a spare lithium battery goes in your carry-on only, never in checked bags, with the terminals protected (original packaging, tape, or a battery pouch). Your airline may set stricter limits, so check with your airline before you fly.
- Battery label
- 95 Wh
- Usable (DC, about 15% held back or lost)
- 85% = 80.8 Wh
- Machine draw (10 cmH2O (we assumed this; pick yours for a better estimate), humidifier off)
- 11.2 W
- Estimated runtime
- 80.8 / 11.2 = 7.2 h
Every battery with the ResMed AirSense 11, humidifier off
| Battery | Works with your machine | Est. runtime | Weight | Flying |
|---|---|---|---|---|
| Needs Medistrom's AirSense 11 kit (P24R11PLK), sold separately | 7.2 h | 1.3 lb | Carry-on | |
| Not listed by its maker for this machine | No estimate | 2.04 lb | Carry-on | |
| Seller says adapters may be needed; ask which one | 23.3 h | 6.5 lb | Cannot fly | |
| Runs your machine's own power supply | 10.5 h | 7.7 lb | Cannot fly | |
| Runs your machine's own power supply | 12.0 h | 7.1 lb | Cannot fly | |
| Runs your machine's own power supply | 11.8 h | 8.16 lb | Cannot fly | |
| Runs your machine's own power supply | 11.8 h | 9.1 lb | Cannot fly |
Under FAA rules a spare lithium battery goes in your carry-on only, never in checked bags, with the terminals protected (original packaging, tape, or a battery pouch). Your airline may set stricter limits, so check with your airline before you fly.
Plan a trip
Can you recharge each day?
Hours, the whole flight. Delta, for example, asks for battery life of 150% of the actual flight time, however long you plan to use it. Leave empty if you will not use it on board.
You need 2 Medistrom Pilot-24 Lites to cover 7.5 hours of sleep between charges. That is 190 Wh and 2.6 lb in total.
Each battery is 100 Wh or less, so the set can go in your carry-on under FAA rules. Airlines can limit how many spares you bring.
Airline-ready summary
Copy this to show at the gate or send to your airline.
CPAP battery summary Battery: Medistrom Pilot-24 Lite, 95 Wh lithium battery. 100 Wh or less. Spare battery: carry-on only, never checked, terminals protected. Machine: ResMed AirSense 11 (a CPAP, a medical device). Estimated runtime per charge: 7.2 h (estimate, assumed 10 cmH2O, humidifier off). Batteries carried: 2 (190 Wh in total).
The humidifier is the big variable
At 10 cmH2O, the ResMed figures behind this estimate put the draw at 11.2 W with the humidifier off and 59 W with its heaviest humidifier and tube setting. Turning the humidifier off is the single biggest way to stretch a battery. If you need moisture, a waterless option (the AirMini's HumidX, or a heat and moisture exchanger) uses no power.
Product specifications, pricing, and availability may change without notice. Verify current specs and compatibility with the manufacturer or retailer before purchasing. CPAP Clarity is not affiliated with any battery or CPAP manufacturer. Always carry your machine's own power supply as a backup.
Related resources
What This Tool Does
It estimates how many hours a battery will run your CPAP, using the power your machine draws at your pressure and humidifier setting, the battery's capacity in watt-hours, and a share of that capacity held back for real-world losses. It also shows which batteries their makers list for your machine and whether each one can fly.
How the Estimate Works
ResMed publishes a battery guide that lists the current its machines draw from a 12 V battery, pressure by pressure and humidifier setting by setting. They are the only setup-by-setup figures we found from any CPAP maker, so they are the base here. The AirSense 10 and AirMini have their own tables. ResMed has not published one for the AirSense 11, so the calculator uses the AirSense 10 figures and says so; for the AirCurve it uses ResMed's S9 VPAP Auto figures, because ResMed says its Air machines draw about the same as their S9 equivalents.
Runtime is the usable watt-hours divided by that draw. A CPAP battery feeding the machine's DC input counts 85% of its label as usable, which covers the reserve a battery keeps back at low voltage and its own output losses. A power station running the machine's power supply starts from the same share (Jackery's own runtime formula also uses 85%), then loses what ResMed measured going through an inverter and the power supply instead of its DC converter. That loss is largest with the humidifier off, where ResMed's guide shows almost twice the current, so on AC the calculator counts about 46% of the label with the humidifier off and 57% with a low humidifier setting. A battery two or more years old loses a further rough 20%.
These are deliberately cautious. On the ResMed Power Station II, ResMed itself quotes "up to 13 hours"; this calculator gives less, because a traveler planning on too high a number is the worse mistake.
What Your Results Mean
The headline is hours of therapy on one full charge, and nights at 7.5 hours each. It is an estimate. Higher leak, colder air, an older battery or a higher pressure than you picked all shorten it.
"Works with your machine" comes from each battery maker's own list. Where the maker does not list your machine, the calculator shows no runtime instead of guessing. The ResMed Power Station II, for example, is listed for the AirSense 10 and AirCurve 10, and ResMed says it does not work with the AirMini.
For a typical night, the Medistrom Pilot-24 Lite on an AirSense 10 at 10 cmH2O with the humidifier off comes to about 7.2 hours. A 293 Wh power station on AC gives about 12.0 hours dry and 6.1 with the humidifier at 4.
Traveling With a CPAP Battery
Spare lithium batteries go in your carry-on only, never in checked bags, with the terminals protected (original packaging, tape over the terminals, or a battery pouch). At 100 Wh or less no airline approval is needed; over 100 and up to 160 Wh needs approval, two spares at most; over 160 Wh cannot go on a passenger flight. These rules come from the FAA's PackSafe page on lithium batteries, and the FAA notes that airlines can set stricter limits.
Using your CPAP on board takes planning. Delta, for example, asks for battery life of 150% of the actual flight time for a PAP machine used in flight. The calculator's trip planner works that out and builds a short summary you can show at the gate.
The machine itself is a medical device. US Department of Transportation rules (14 CFR 382.121) say airlines must not count assistive devices toward your carry-on limit, and airlines list CPAP machines among them. Ask your provider whether your settings need any change for altitude; never change your pressure on your own.
Frequently Asked Questions
How long will a CPAP battery last?
It depends most on the humidifier. ResMed's battery guide puts an AirSense 10 at 11.2 W at 10 cmH2O with the humidifier off. On that figure a 95 Wh battery gives an estimated 7.2 hours, about 1.0 nights of 7.5 hours. With the heated tube at 30°C and the humidifier at 8, the same battery gives about 1.4 hours. Pressure matters too. The same machine draws 8.4 W at 6 cmH2O and 19.9 W at 20.
Can I bring a CPAP battery on an airplane?
Under FAA rules a spare lithium battery goes in your carry-on only, never in checked bags, with the terminals protected. At 100 Wh or less, no airline approval is needed, and the Medistrom Pilot-24 Lite (95 Wh) and ResMed Power Station II (97 Wh) are in that group. Over 100 Wh and up to 160 Wh needs airline approval, two spares per person at most. Over 160 Wh cannot fly. Despite its name the EXP96 Pro is 307 Wh, and portable power stations like the Jackery Explorer 300 (293 Wh) are over the limit too. Airlines can set stricter rules, so check with yours before you fly.
What is the difference between DC and AC batteries for a CPAP?
A CPAP battery feeds the machine's DC input directly; a power station runs the machine's own power supply from an AC outlet, which adds a conversion. This calculator counts 85% of a DC battery's label as usable. On AC it also counts the share ResMed measured surviving an inverter and the machine's power supply, which is smallest with the humidifier off: about 46% of the label at that setting and 57% with a low humidifier setting. ResMed's battery guide "strongly" recommends DC-to-DC converters over inverters, and if you must use an inverter, a pure sine wave one.
Should I turn off the humidifier on battery power?
If runtime matters, yes. At 10 cmH2O, ResMed's figures for the AirSense 10 go from 11.2 W with the humidifier off to 27.6 W with it at 4, and 59 W with the heated tube at 30°C and the humidifier at 8, about 5.3 times the dry draw. ResMed's own advice is to turn the humidifier off when using a battery. A waterless option such as the AirMini's HumidX uses no power.
How many watts does a CPAP machine use?
ResMed's battery guide lists current at 12 V, which works out to 8.4 to 19.9 W for an AirSense 10 with the humidifier off (6 to 20 cmH2O), and 5.4 W for an AirMini at 10 cmH2O. The rating printed on a power supply is its maximum, not what the machine draws overnight. Philips and React Health do not publish typical overnight draws, so for those machines measure yours with a plug-in power meter and enter it in the calculator.