Published September 24, 2026 · Reserve Current editorial guide
Quick answer: A CPAP without heated humidification uses little energy; the humidifier and heated tubing can multiply it several times, and an AC inverter adds large losses. ResMed's own battery sizing for an AirSense 10 at 10 cmH₂O over 8 hours is about 7Ah at 12V without humidification versus about 28Ah with it.
Medical note: this is energy planning, not medical advice. If you rely on a CPAP or another powered medical device, agree an outage plan with your clinician and equipment supplier, and ask your utility whether it offers a medical priority or notification program.
Know your machine's real consumption
The power supply rating on the brick is its maximum, not what the machine draws all night. Pressure setting, leak, humidifier level and heated tubing all change consumption. The most reliable number is a measurement of one normal night with a plug-in energy meter, or the battery table in your device manufacturer's documentation.
The humidifier changes everything
ResMed's battery guide sizes an AirSense 10 at 10 cmH₂O for an 8-hour night at about 7Ah on a 12V battery without humidification, and about 28Ah with the humidifier at setting 4. That is roughly 84Wh versus 336Wh of battery energy — about four times as much. During an outage, ask your clinician whether running without heated humidification for a few nights is acceptable for you.
DC beats AC for a CPAP
Plugging the CPAP's normal power brick into the station's AC outlet means converting battery DC to AC and back to DC. ResMed notes that an inverter setup needs roughly two to three times the battery capacity of a DC converter setup, and specifies a pure sine wave inverter when AC is used. A manufacturer-approved DC converter from the station's 12V output avoids that double conversion. Check the connector, voltage and approval for your exact model.
Size the station
Multiply your measured nightly energy by the number of nights you want to cover, add your conversion assumption and keep 20% or more in reserve for a medical load. Then add phones, lights and anything else sharing the same battery. The CPAP battery calculator compares the AC outlet with a DC converter, with and without the humidifier.
Test before the outage
Charge the station, run the CPAP from it for a full night at home while the grid is on, and note the remaining state of charge in the morning. That single test is worth more than any estimate on this page.
Frequently asked questions
How much battery does a CPAP need for one night?
Far less without the heated humidifier. ResMed's battery guide sizes an AirSense 10 at 10 cmH₂O for 8 hours at about 7Ah on a 12V battery (roughly 84Wh) without humidification, and about 28Ah (roughly 336Wh) with the humidifier at setting 4. Check the figures for your own model.
Should I run my CPAP from the power station's AC outlet or DC?
A DC route with the manufacturer's approved converter avoids the inverter's conversion losses. ResMed notes that running through an inverter needs roughly two to three times the battery capacity of a DC converter setup. If you use AC, ResMed specifies a pure sine wave inverter.
Can a 1,000Wh power station run a CPAP for several nights?
Without the humidifier and via a suitable DC path, the energy is there for several nights on paper. With the humidifier and an AC inverter, expect a small fraction of that. Test a full night while grid power is still available.