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Medical note: I’m not a doctor. If you depend on a CPAP or other medical device, talk to your physician and your equipment supplier (DME) about outage planning. Many utilities also offer medical-baseline programs and priority restoration, so ask yours.
A CPAP is one of the easiest loads to back up: small and steady. It is also one of the most important, because losing it in an outage means a bad night or worse. Here is how to size a power station for yours, step by step.
Step 1: Find the real draw (it’s lower than the power brick says)
The number on your CPAP’s power supply is a maximum, not what it actually uses. ResMed’s AirSense 11, for example, ships with a 90 W power supply, but actual draw is usually much lower. The biggest variables are:
- Heated humidifier and heated tubing: this is the big one. It can roughly double or triple consumption.
- Pressure setting: higher pressure means more motor power.
- Mask leak: a leaky mask makes the blower work harder.
Typical real-world figures for modern machines:
| Setup | Typical average draw |
|---|---|
| CPAP, no humidifier, moderate pressure | ~20–40 W |
| CPAP with heated humidifier | ~50–90 W |
| CPAP with humidifier + heated tube | ~60–100 W+ |
The best figure is your own. Plug the CPAP into a watt meter for a whole night and read the total Wh. [AFFILIATE LINK: plug-in electricity usage monitor]
Step 2: AC vs DC (DC is a big efficiency win)
Running a CPAP from the power station’s AC outlet goes battery → inverter (AC) → CPAP power brick (back to DC), losing energy twice. Most CPAP makers sell a DC power converter/cable that plugs into a 12 V car-style port, skipping the inverter. ResMed, for example, sells a DC converter for the AirSense line. With DC you can often gain 20–30% more runtime. Get the cable made or approved for your specific machine. [AFFILIATE LINK: CPAP DC power cord for your model]
Step 3: Do the math
Nights = (battery Wh × efficiency) ÷ (CPAP watts × hours per night)
Use 0.85 efficiency for AC, ~0.9 for DC.
Worked example A, humidifier off, DC cable:
– CPAP averages 30 W × 8 h = 240 Wh/night
– Anker SOLIX C1000: 1,056 Wh × 0.9 ≈ 950 Wh usable
– 950 ÷ 240 ≈ ~4 nights
Worked example B, humidifier on, AC outlet:
– CPAP averages 75 W × 8 h = 600 Wh/night
– BLUETTI AC180: 1,152 Wh × 0.85 ≈ 979 Wh usable
– 979 ÷ 600 ≈ ~1.6 nights
Small-unit check, humidifier off, DC:
– A ~500 Wh class unit × 0.9 ≈ 450 Wh → 450 ÷ 240 ≈ ~1.8 nights
Capacities are from the manufacturers’ product pages. Confirm the current specs before buying.
Step 4: Pick features that matter for CPAP users
- UPS / EPS mode. Leave the CPAP plugged in through the power station every night. If the grid drops, it switches over automatically, usually without waking you. Check the switchover time on the spec sheet: Anker lists <20 ms UPS on the C1000, EcoFlow lists within 30 ms on the DELTA 2, and BLUETTI lists ≤20 ms on the AC180. Some CPAPs may still briefly restart. Test yours.
- Quiet operation. Fans that ramp up at 2 a.m. are annoying. Look for a “quiet” or low-noise mode and keep loads light.
- LiFePO4 chemistry. It handles the frequent cycling of nightly UPS use far better than older chemistries.
- Solar input. For multi-day outages, a 100–200 W panel can refill a night’s worth of CPAP use in a few hours of sun. [AFFILIATE LINK: 200W portable solar panel]
Our CPAP picks
A 1 kWh class LiFePO4 unit with UPS covers several nights with the humidifier off. [AFFILIATE LINK: Anker SOLIX C1000] · [AFFILIATE LINK: EcoFlow DELTA 2] · [AFFILIATE LINK: BLUETTI AC180]
Quick sizing cheat sheet
| Need | Minimum sensible setup |
|---|---|
| CPAP, 1–2 nights, humidifier off | ~500 Wh LiFePO4 + DC cable |
| CPAP, 3–4 nights or with humidifier | ~1,000 Wh class with UPS |
| CPAP for a week+ | 1 kWh + 200 W solar, or 2 kWh+ |
The bottom line
A CPAP is easy to back up: measure it, switch to DC, turn the humidifier off if you can, and a 1 kWh class LiFePO4 unit with UPS mode covers several nights. Add a solar panel and you can ride out a week. (Other brands such as Jackery sell similar 1 kWh class units. Use the same math with their listed Wh.)
Free: Outage Runtime Cheat Sheet
Grab the free cheat sheet with these formulas and a fill-in appliance table. It’s drawn from my book DIY Home Battery Power for Beginners (as Mr E Powers).
FAQ
Can I run a CPAP directly from a car battery? Technically yes, with a DC cable, but deep discharges damage regular car batteries, and running a car to recharge indoors or in an attached garage is a carbon-monoxide hazard. A LiFePO4 power station is safer and easier.
Do I need an electrician? No. A CPAP plugs straight into the power station. You only need an electrician if you want to power hardwired house circuits.
Sources
Manufacturer specs checked October 26, 2026:
– Anker SOLIX C1000 product page
– BLUETTI AC180 product page
– EcoFlow DELTA 2 product page and user manual