What size power station do you need for a CPAP?
For dry therapy, budget roughly 65Wh per night — so about 200Wh covers three nights. With heated humidification, budget roughly 320Wh per night, which means around 1,000Wh for the same three nights. The humidifier setting changes the answer fivefold, so decide that first.
Power-draw figures for the machines below are provisional estimates, not yet our own meter readings. See how we test.
Sizing is simple arithmetic once you fix one variable: whether the heated humidifier is running. Everything else is secondary.
Work in watt-hours per night rather than in "nights", because watt-hours are the unit batteries are actually sold in and the only figure you can check against a spec sheet.
The per-night figures
An eight-hour night at typical therapy pressure, running from the AC outlet, after losses:
Humidifier off — about 65Wh per night. Humidifier on — about 320Wh per night. Travel machine with waterless humidification — about 50Wh per night.
Those already account for 90% usable capacity and 85% inverter efficiency, so you can compare them directly against a battery's rated watt-hours.
| Nights | Humidifier off | Humidifier on |
|---|---|---|
| 1 night | ~65Wh | ~320Wh |
| 2 nights | ~130Wh | ~640Wh |
| 3 nights | ~200Wh | ~960Wh |
| 5 nights | ~330Wh | ~1,600Wh |
| 7 nights | ~460Wh | ~2,250Wh |
Which tier that puts you in
Around 300Wh — the entry tier. Four nights dry, or a single night humidified. Right for a short outage or a weekend where you are willing to run dry, and light enough to carry.
Around 1,000Wh — the practical sweet spot. Roughly twelve nights dry or two and a half humidified, with spare capacity to charge phones and run a lamp through an outage. This is the tier most people should buy if the battery is for emergencies rather than travel.
2,000Wh and up — only worth it if you need humidification every night through a long outage, or you are powering a household's worth of other things alongside the CPAP.
Three things that make the real number worse
Higher therapy pressure raises blower draw. The figures above assume a middle-of-the-road pressure; anyone on a much higher setting should add margin.
Cold reduces usable capacity on any lithium battery, and a cold humidifier chamber takes more energy to hold temperature. Camping in winter, assume meaningfully less than rated.
Bilevel machines draw more than fixed-pressure CPAP because they cycle between two pressures. Add roughly a third.
Round up. Running out at 4am is a far worse outcome than carrying a slightly heavier battery.
- What size power station do I need for 3 nights of CPAP?
- About 200Wh with the humidifier off, or about 960Wh with it on, for an eight-hour night at typical pressure. In practice that means a 300Wh unit dry, or a 1,000Wh unit humidified.
- Is a 1000Wh power station enough for a CPAP?
- Comfortably. Roughly twelve nights with the humidifier off, or about two and a half nights with it on, plus spare capacity for phones and lights.
- How many watt-hours does a CPAP use per night?
- Roughly 65Wh over eight hours with the humidifier off, and roughly 320Wh with heated humidification on, after inverter and capacity losses.
Keep reading
Keep reading
- How long will a power station run a CPAP?
A 1,000Wh power station runs a typical CPAP for about 98 hours — roughly 12 nights — with the humidifier off.
- Does the CPAP humidifier drain the battery?
Yes — dramatically.
- CPAP battery or portable power station — which should you buy?
Buy a dedicated CPAP battery if the only job is the CPAP and you travel with it: DC-native, lighter, and sub-100Wh models are the simplest category to fly with.
- Should you run a CPAP on DC or AC from a battery?
Run it on DC if your machine supports it.