How do you run a CPAP during a power outage?

How to run a CPAP during a power outage

Switch the humidifier off first — that one setting cuts draw from about 40W to about 8W and multiplies your runtime fivefold. A 300Wh battery then covers roughly three nights of dry therapy instead of five and a half hours with the heater on.

Our pick for this

We earn a commission on these links at no extra cost to you. It does not change the runtime figures above — the maths is shown so you can check it.

Jackery Explorer 300
Covers a typical outage
At 292Wh this is roughly three nights of dry therapy — which covers most outages — and it is small enough to keep charged in a cupboard without thinking about it.
Check price on Amazon
Bluetti Elite 100 V2
If you run humidified
1,024Wh is the first tier where humidified therapy lasts more than one night: about 19.6 hours with the heater on, or 12 nights without it.
Check price on Amazon

Power-draw figures for the machines below are provisional estimates, not yet our own meter readings. See how we test.

The decision that matters is made before the outage, not during it: whether you will run humidified. Everything else is secondary, because that single setting changes how long your battery lasts by a factor of about five.

The order to do things in

1. Turn the humidifier off. On a battery this is the whole ballgame. Draw drops from roughly 40W to roughly 8W.

2. Turn off heated tubing if you have it. That is a third heating element, separate from the chamber.

3. Run the machine on DC if it supports it. A 12V or 24V cable skips the battery's inverter and returns about 12% more runtime — see DC vs AC.

4. Leave everything else off the battery. A phone charger is trivial next to a CPAP; a fridge is not.

What each battery size actually buys you

Running a typical CPAP from the AC outlet of a power station, at around 10 cmH₂O:

Nights of therapy per charge, by battery size
Battery	Humidifier off	Humidifier on
95Wh (CPAP battery)	9.1 hours — one night	1.8 hours
148Wh	14.2 hours — 1.8 nights	2.8 hours
292Wh	27.9 hours — 3.5 nights	5.6 hours
1,024Wh	97.9 hours — 12.2 nights	19.6 hours — 2.4 nights

Assumes 90% usable capacity, 85% inverter efficiency, 8W dry and 40W humidified at a typical pressure, eight hours a night. Draw figures are provisional pending our own meter testing — see How We Test.

The honest trade

Dry air is uncomfortable. It causes a dry throat and nasal congestion, and for a night or two most people find it a great deal easier to live with than skipping therapy altogether. The therapy pressure itself does not change when the humidifier is off.

If you cannot tolerate dry air at all, size the battery for humidified use rather than planning to switch it off: budget about 320Wh per night instead of about 65Wh.

If the outage is open-ended

A battery you cannot refill is a countdown. Pair the station with a way to put charge back in — a 100W solar panel replaces a dry night's 64Wh in well under an hour of good sun, and the car is a slower but reliable option. See recharge times by method.

What is the first thing to do with a CPAP when the power goes out?: Turn the humidifier off before anything else. It takes total draw from roughly 40W to roughly 8W, which multiplies battery runtime by about five.
How big a battery do I need to get through a typical outage?: For dry therapy, about 65Wh per night — so a 292Wh unit covers roughly three nights. Humidified, budget about 320Wh per night, which means roughly 1,024Wh for the same three nights.
Can I plug a CPAP into a UPS instead?: A standard desktop UPS is built to hold a computer up for minutes, not a CPAP for hours, so capacity is usually the limit rather than the connection. Check the unit's watt-hour rating against about 65Wh per dry night.

What to actually buy