Backing up a CPAP with a power station
Read this first. No calculator, including ours, can guarantee power for equipment you depend on for your health. Use these numbers to shortlist a station, confirm with your CPAP and station makers, talk to your care provider, and test a full night at home while the grid is still there to fall back on. If your therapy is life-sustaining, plan with your provider for more than one backup.
Short answer: with a heated humidifier and heated tube, a CPAP like the ResMed AirSense 10 averages about 34W; without them, about 7W. We plan with a cautious 40W, so one 8-hour night needs about 320Wh, and you should look for at least 510Wh on the box. Every in-stock station we cover clears that. The decisions that matter more are the humidifier, AC versus DC, and testing.
What a CPAP actually draws
ResMed publishes average power figures for its AirSense 10 machines. They show how much the comfort features dominate:
| Setup | Average draw | 8-hour night |
|---|---|---|
| CPAP only | about 7 W | about 56 Wh |
| With heated humidifier | about 22 W | about 176 Wh |
| With humidifier and heated tube | about 34 W | about 272 Wh |
Pressure setting, room temperature and humidity change these numbers, and other machines differ (we couldn’t find comparable published figures for Philips DreamStation units). Check your machine’s manual, or measure it with a plug-in watt meter for a full night.
Turning the humidifier and heated tube off cuts the draw by about 70–80%, but that’s a therapy decision — ask your care provider before changing settings.
Why DC can matter more than battery size
A power station’s AC outlets run through an inverter, and the inverter uses power just to stay on. With a big load that overhead hardly matters; with a 7–10W CPAP it can use more energy than the CPAP itself. Independent tests published by Outdoor Life found stations delivered only 49–77% of their rated capacity at about 34W, compared with 76–92% at 380W.
On our estimates, a 10W CPAP through AC outlets needs a station with about 210Wh for one night. The same CPAP powered from the station’s DC output needs only about 120Wh, because there’s no inverter in the way. That saving depends on the inverter being off: if a fridge or anything else is running from the AC outlets overnight, the inverter is on anyway and DC saves little.
- Use the CPAP maker’s DC adapter if one exists for your machine. ResMed sells a DC/DC converter for the AirSense 10. We couldn’t confirm an official one for the AirSense 11 on ResMed’s US site — ask ResMed or your supplier.
- Don’t improvise cables. Use only adapters approved for your machine.
- Check the station’s power-saving settings. Some stations can switch AC or DC output off automatically when the load is small or after a set time, which could cut power to a CPAP mid-night. Check your station’s manual and app, and turn that off for overnight use.
Switchover: will the CPAP keep running when the power cuts?
If the CPAP is plugged into the station while the station is plugged into the wall, most stations switch to battery when the grid fails. How fast varies:
| Station | Switchover |
|---|---|
| ALLPOWERS R1500 | 15 ms |
| BLUETTI AC180, AC200L | 20 ms |
| Jackery Explorer 1000 v2, Anker SOLIX C1000 | under 20 ms |
| EcoFlow DELTA 2, DELTA 2 Max, RIVER 2 Pro | up to 30 ms (EcoFlow calls it EPS, not 0 ms UPS) |
These are manufacturer claims. Whether your particular CPAP rides through a 20–30 ms gap without restarting is something only a test will tell you — unplug the station from the wall while the CPAP is running (awake, not asleep) and watch what happens.
How big a station, honestly
- CPAP only, with humidifier, one night: look for at least 510Wh. A 768Wh RIVER 2 Pro gives about 12.3 hours on our estimate; a 1kWh station about 16.3. Bigger is a safety margin, not waste — a second night, a cold room, an older battery.
- CPAP plus fridge overnight: about 1,100Wh. Of the 1kWh-class stations, the 1,152Wh AC180 and R1500 pass on our numbers, with little to spare; the 2,048Wh DELTA 2 Max and AC200L give about 15.0 hours.
- Several nights: plan for recharging — a car, solar panels, or a neighbor with power — rather than one enormous battery, and keep a separate CPAP-only battery if your provider recommends it.
Rehearse before you need it
- Charge the station fully.
- Set the CPAP exactly as you sleep with it — same pressure, humidifier and tube settings.
- Run a whole night from the station at home, with the grid available as backup.
- In the morning, note the battery percentage left. If it’s under about 30%, size up or change your setup.
- Repeat whenever you change settings, the machine, or the station — and once a season, since batteries age.
Other things to arrange
- Tell your utility. Many utilities run medical programs. PG&E’s Medical Baseline program, for example, offers extra notifications and a lower rate. Programs like this don’t keep your power on during an outage, so you still need a backup plan. Check what yours offers.
- Read the FDA’s guide to preparing home medical devices for outages (linked below), and ask your equipment supplier about backup options.
- Never use a fuel generator indoors or in a garage to run medical equipment.
Try your own setup in the planner, set up for a CPAP overnight — tick “without the heated humidifier” if that’s how you sleep, and under “Fine-tune” tick “Run small devices from DC/USB ports” to see the difference.
Sources
- ResMed: Power consumption of AirSense 10 and AirCurve 10 devices (PDF) — average draw with and without humidifier and heated tube
- ResMed: CPAP batteries and power converters — DC/DC converter and Power Station II
- FDA: Home use devices — how to prepare for and handle power outages (PDF) — planning for medical equipment during outages
- PG&E Medical Baseline Program — example of a utility medical program
- Outdoor Life: best portable power stations (Jan 2026) — independent tests showing low efficiency at small loads