Guide · 2026-11-11

How long can a power station run a CPAP?

Divide usable watt-hours by the watts the machine draws. For a ResMed AirSense 11, the Americas user guide lists typical power consumption of 56.1 W (111.5 VA) and peak power consumption of 73.2 W (137.6 VA) in the 65 W power-supply section. RunTime's load note uses the typical 56.1 W. That is the published system figure. It is not a clamp-meter reading of your machine tonight, and it does not promise a particular humidifier setting.

The hour math, and what moves it

On AC, usable watt-hours are the station's published capacity times inverter efficiency. Hours are that result divided by 56.1 W, or by whatever wattage you type instead. RunTime defaults the AC path to 85% because the station pages in this library do not print an inverter efficiency. Temperature, battery age, and whether you are on the inverter or a proper DC supply all change the night. Open the AirSense 11 load in RunTime and replace the capacity with the watt-hours printed on your station.

The station's 12 V car port is not a substitute for ResMed's 24 V supply. Do not count on that cigarette socket just because the watt number looks small. How to read a power station label separates the AC inverter from the DC ports.

Other loads live in the same calculator

Starlink is already a cited load on the loads page, with the published average ranges for Standard 4 and V5. A fridge-sized question belongs there too, but only after you type that fridge's own watts. A cycling compressor is not given a single watt on this site. None of this is a recommendation of a station. The Amazon search on a station page, when it is present, is a name search with the Associates disclosure. It is not a best-buy pick.