How big a battery backup does a CPAP need?
A CPAP on its own uses very little power. The heated humidifier is what drains a battery, so the setting you choose matters more than the battery you buy.
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The short answer
A 2,000 Wh power station runs a ResMed AirSense 10 CPAP for about 31 nights with the humidifier off, or about 6–9 nights with it on. That assumes 8 hours a night at 8–15 cm H2O, ResMed’s published draw, and 85% of the battery usable. Any of the units below keeps a CPAP running through a 2–3 day outage at these settings, even with the humidifier and heated tube on.
- 7 W
AirSense 10 AutoSet, machine only, at 8–15 cm H2O.
Source: ResMed- 22 W
The same machine with the heated humidifier on (humidity 6).
Source: ResMed- 34 W
With the humidifier and a heated tube set to 28°C.
Source: ResMed
How many nights does each size run a CPAP?
Nights depend far more on the humidifier than on the battery. Turning it off roughly triples the nights you get from the same unit.
| Unit | Capacity | Humidifier off (7 W) | Humidifier on (22 W) | Humidifier + heated tube (34 W) |
|---|---|---|---|---|
| EcoFlow DELTA 2 Max | 2,048 Wh | 31 nights | 9 nights | 6 nights |
| Jackery Explorer 2000 Plus | 2,042 Wh | 30 nights | 9 nights | 6 nights |
| Anker SOLIX F3800 | 3,840 Wh | 58 nights | 18 nights | 12 nights |
Manufacturer spec capacity · Our estimate nights, using 85% of capacity and ResMed’s measured draw for an AirSense 10 AutoSet (8–15 cm H2O, EPR 2, humidity 6, heated tube 28°C), 8 hours a night, rounded down to whole nights. How we calculate
On AC power, a power station’s inverter also draws a little power of its own just by being on. At a load as small as 7 W, that can cut the humidifier-off nights noticeably. Check your own machine’s figures in its manual: newer models, higher pressures and higher humidity settings all draw more.
Which size fits your nights
- One or two nights
- At the settings above, even a 1,000 Wh station gets about 3 nights with the humidifier and heated tube on. A 2,000 Wh unit leaves room for phones and a lamp.
- Two to three days
- A ~2,000 Wh station gets you 6–9 nights with the humidifier on at the settings above, so it keeps the CPAP running through the outage with nights to spare.
- CPAP plus the fridge
- Size from the combined total. A fridge uses far more than a CPAP, so it sets the size. See the fridge and freezer guide.
Does a DC cord make the battery last longer?
Usually, yes. Plugging the CPAP’s normal power brick into an AC outlet sends the battery’s power through the station’s inverter and then back down to DC inside the brick. A DC cord or converter made for your machine skips that round trip. ResMed sells one for the AirSense 11 that runs from a 12 V or 24 V source, and notes that skipping the humidifier and heated tube reduces power use (ResMed).
Use only the cord your CPAP’s maker sells for your model. Our table still assumes 85% usable on DC, so treat the extra nights as a bonus.
What about a BiPAP, oxygen concentrator or refrigerated medication?
BiPAP. A bilevel machine draws a little more. ResMed lists its AirCurve 10 VAuto at about 9 W alone, 23 W with the humidifier and 41 W with the heated tube (PS 6, max IPAP 25, min EPAP 8 cm H2O) (ResMed). At 8 hours a night, a 2,000 Wh station runs it for about 24, 9 and 5 nights.
Oxygen concentrators. A stationary concentrator is a much bigger load. The Philips EverFlo averages 350 W (Philips). Running all day, that is about 5 hours on a 2,000 Wh station and about 9 hours on the 3,840 Wh F3800, using 85% of capacity.
Refrigerated medication. Many insulins can stay unrefrigerated at 59°F to 86°F for up to 28 days, according to the FDA. Check the label for yours. For other medicines, ask your pharmacist, and add a small medication fridge to the calculator if you need one.
For oxygen or life-support equipment, check the device’s power needs with your provider. A backup should never be the only plan.
Three units for a CPAP
Specs are the manufacturer's. Nights are our estimate for the ResMed AirSense 10 at the settings above, 8 hours a night, CPAP only.
Best for most bedrooms
EcoFlow DELTA 2 Max
6–31 nights for the CPAP at the settings above Our estimate
2,048 Wh · 2,400 W (4,800 W surge) · LFP, 3,000 cycles · about 50 lb Manufacturer spec
About 31 nights with the humidifier off and 6–9 with it on, at the settings in the table above. Room left over for phones and a lamp.
Trade-off: At about 50 lb it is heavy for a nightstand, so plan on floor space beside the bed.
Best if you add a fridge later
Jackery Explorer 2000 Plus
6–30 nights for the CPAP at the settings above Our estimate
2,042 Wh · 3,000 W (6,000 W surge) · LiFePO₄, 4,000 cycles · 61.5 lb Manufacturer spec
Nearly the same CPAP nights as the DELTA 2 Max, and it expands to 12 kWh with add-on packs if you later want the kitchen on it too.
Trade-off: Heavier for the same capacity, at 61.5 lb.
Most nights of these picks
Anker SOLIX F3800
12–58 nights for the CPAP at the settings above Our estimate
3,840 Wh · 6,000 W (9,000 W surge) · LFP, 3,000+ cycles · 132 lb Manufacturer spec
Roughly double the nights of the 2,000 Wh units, 12–58 depending on the humidifier.
Trade-off: At 132 lb on wheels it lives in one spot, and it is far more battery than a CPAP alone needs.
Make the battery last more nights
- Ask about the humidifier. Turning it and the heated tube off is the biggest saving. Check with your doctor first.
- Use a DC cord if your CPAP’s maker sells one for your model.
- Turn the station’s AC outlets off when nothing is plugged into them.
- Keep the station charged. Top it up when a storm is in the forecast, and recharge by day from solar or a car if the outage runs long.
Common questions
How many watts does a CPAP use?
ResMed measured its AirSense 10 AutoSet at about 7 W with the machine alone, 22 W with the heated humidifier and 34 W with the humidifier and heated tube, at 8–15 cm H2O. Higher pressures and humidity settings draw more. Your machine's manual or maker can give the figure for your model.
Should I turn off the humidifier during an outage?
It's the biggest single lever on battery life, roughly tripling to five-times the draw in ResMed's figures. Some people find therapy uncomfortable without it, so ask your doctor or sleep provider before changing settings.
Can I run a CPAP from a power station's 12 V outlet?
Yes, if your CPAP's maker sells a DC cord or converter for your model, such as ResMed's AirSense 11 DC converter. Running on DC skips the station's inverter, so less of the battery is lost to conversion.
Will a power station run an oxygen concentrator?
It can, but not for long. A stationary concentrator like the Philips EverFlo averages about 350 W, which a 2,000 Wh station runs for about 5 hours, so talk to your provider about backup cylinders and a plan beyond the battery.
