Running a CPAP on a power station overnight

With the heated humidifier and heated tube on, a ResMed AirSense 10 draws about 34 W, and the 288 Wh Anker SOLIX C300 runs it for 5 h 19 min on AC, short of a full 8 hour night. Turn the heat off and the machine alone draws 7 W, which stretches the same station to 1.8 nights through the AC outlet or 3.4 nights on a 12 V DC cord, because DC skips the inverter's own draw.

Where the CPAP numbers come from

ResMed publishes a power consumption sheet for its Air10 machines (ResMed, Power consumption of Air10 devices). For the AirSense 10 AutoSet it lists 7 W running with the device only, 22 W with the humidifier, and 34 W with the humidifier and the ClimateLineAir heated tube, at a humidity setting of 6 and a tube temperature of 28°C. Other brands, models and pressures draw different amounts, so the figures below are a starting point. Your machine's manual lists its power supply rating and any approved DC cord or battery, and your clinician can say whether skipping humidification for a night is reasonable for you.

Worked example 1: the same small station, three ways

Inputs: the Anker SOLIX C300 at its published 288 Wh, 90% of it treated as usable, and the ResMed figures above. Anker SOLIX doesn't publish inverter efficiency or idle draw, so the labelled defaults from the methodology page apply. The engine runs each line at render time.

Dropping the heat cuts the machine's draw by almost four fifths, but on AC the runtime only improves about 2.7 times, because the assumed 10 W inverter draw is now 56% of what leaves the battery. Moving the dry machine to the 12 V port removes the inverter and that is where the big jump comes from.

Worked example 2: keep the humidifier, lose the heated tube

Inputs: the Goal Zero Yeti 500 at 499 Wh, with a 162 W rated 12 V port.

The DC line assumes the machine pulls the same 34 W through a maker-approved DC cord as it does from its own power supply. That is our simplification, not a ResMed figure, and the cord's own losses are not included. Whether your machine can heat its humidifier on DC at all is in its manual.

CPAP nights by power station

Typical nights of 8 hours from each station's published capacity, with the same labelled assumptions. The DC column uses the 12 V car port only where the maker publishes its watt rating; a "12V 10A" listing without watts is shown as not rated.

The Explorer 100 Plus has no AC outlet and no rated 12 V port, so it would need a USB-C route that your CPAP maker supports. The Elite 100 V2's car outlet is listed in amps only, so for DC at this size the RIVER 2 Pro is the one with a rated 12 V port. See the EcoFlow RIVER 2 Pro page for its 12 V port rating and runtimes, or the SOLIX C300 DC if you only ever plan to run DC devices.

What changes the answer

• Leaving the AC outlet on all night for a light load. At 7 W the inverter's idle draw can be bigger than the machine. If your CPAP has an approved DC cord, the 12 V port avoids it.
• Assuming any 12 V port will do. Check the port's watt rating against the DC cord's rating in your CPAP manual. A port that is not rated in watts, or a cord that is not approved for your machine, is a reason to stay on AC.
• Using another machine's watts. These are ResMed's AirSense 10 figures at one set of pressures and heat settings. Higher pressure, a colder bedroom and a higher humidity or tube setting all raise the draw.
• Counting on one night only. An outage that lasts longer needs a recharge. The solar calculator shows refill time, and the CPAP scenario page runs any station against an 8 hour night.
• Changing therapy settings to save power. Humidity and heat settings are part of your therapy. Ask your clinician before turning them down or off.