Home / CPAP
What size power station do you need for a CPAP machine?
For one night, a 500 Wh power station is enough if you turn the heated humidifier off. A typical CPAP uses about 35 W without a heated humidifier and around 75 W with one, so an 8-hour night takes roughly 280 Wh or 600 Wh. For a weekend with the humidifier on, plan on 1,500 Wh. Output isn't a problem: any unit with a 300 W AC outlet runs a CPAP. Capacity is what you're choosing.
This page is general sizing information, not medical advice. Your machine's real power use depends on its model, pressure setting and humidifier level. Don't change your pressure settings to save power, and check with your equipment supplier before relying on battery power.
Nights per charge
Based on 8 hours a night through the power station's AC outlet, with 85% of the rated capacity usable (the inverter loses the rest as heat).
| Power station | Humidifier off (~35 W) | Humidifier on (~75 W) |
|---|---|---|
| 300 Wh | About 7 hours (most of a night) | About 3.5 hours |
| 500 Wh | About 1.5 nights | About 6 hours |
| 1,000 Wh | About 3 nights | About 1.4 nights |
| 1,500 Wh | About 4.5 nights | About 2 nights |
| 2,000 Wh | About 6 nights | About 2.8 nights |
The sum behind it:
Nights = capacity (Wh) × 0.85 ÷ (CPAP watts × 8 hours)
Example: 1,000 Wh × 0.85 = 850 Wh usable. With the humidifier off, 35 W × 8 h = 280 Wh a night. 850 ÷ 280 ≈ 3 nights.
Why the humidifier changes everything
The blower that makes the air pressure is efficient. What uses the power is heat: the heated humidifier warms a water tank, and a heated tube (if you have one) keeps the air warm on its way to the mask. Together they can more than double the draw.
If you're comfortable without them for a night or two, turning them off is the single biggest way to stretch a battery. Some people use the humidifier chamber unheated ("passover" humidification), which adds a little moisture without the power cost. Whether that's comfortable for you is worth testing at home first, not on the first night of a trip.
DC or AC: plug in the right way
Most CPAPs run on DC power internally. Their power brick turns the wall's AC into DC. When you plug that brick into a power station's AC outlet, energy gets converted twice: battery DC to AC in the power station's inverter, then AC back to DC in the brick. Each step loses some.
- Best: the manufacturer's DC cable or DC converter for your model, plugged into the power station's 12 V car socket. You skip the inverter, typically gaining 10–20% more run time, and you can switch the AC side off entirely.
- Fine: the normal power brick in the AC outlet. Simple and works with everything. Our table above assumes this.
- Avoid: cheap third-party adapters that aren't approved for your machine.
Find your machine's real number
Our 35 W and 75 W figures are typical, not exact. Two ways to get yours:
- Check the manufacturer's battery or travel guide. The big CPAP makers publish power-use figures for their machines at different pressures and humidifier settings.
- Measure it. Plug the CPAP into a plug-in power meter (about $20) for a full night with your normal settings, then read the Wh. Or run it from the power station for a night at home and note how many percent it used.
Don't size from the number printed on the power brick (for example "90 W"). That is the most it can supply, not what your machine uses on an average night.
Camping tips
- Test at home first. Run one full night from the power station before you rely on it in a tent.
- Cold cuts capacity. Batteries deliver less in the cold. Keep the power station inside the tent or vehicle, off the ground. Many LiFePO4 units can't recharge below freezing (32 °F / 0 °C).
- Recharge by day. A single 100 W solar panel in good sun puts back around 300 Wh a day in practice, roughly one night with the humidifier off.
- Turn off what you don't need. Switch off the power station's AC output when you use DC, and turn off its screen or Wi-Fi app if it has one.
Power outage backup
For use at home during outages, look for a power station with a UPS or pass-through mode: the CPAP stays plugged into the power station, which stays plugged into the wall, and it switches to battery when the power cuts. Check the switchover time in the spec sheet (often under 30 milliseconds) and test it by flipping the breaker while the machine runs.
If you rely on a CPAP, also tell your equipment supplier and your electric utility. Many US utilities keep a list of customers who use medical equipment and may give them advance warning of planned shutoffs.
Adding phone charging, lights or a fan? Add everything and see the size you need.
Open the calculatorFAQ
How many nights will a 500 Wh power station run a CPAP?
About 1.5 nights with the humidifier off and less than one full 8-hour night with a heated humidifier on, through the AC outlet. A DC cable stretches that further.
Is it better to run a CPAP from DC or AC?
DC, if your machine's maker sells a DC cable or converter for it. It skips the inverter, which typically wastes 10–20% of the energy.
Does a CPAP need a big inverter?
No. A CPAP draws well under 150 W even with a heated humidifier and has no large start-up surge, so a 300 W AC output is enough. Capacity (Wh) is what limits you. If W and Wh are confusing, see watts vs watt-hours, explained.
Can I use a power station as a backup for my CPAP during outages?
Yes. Look for UPS or pass-through mode, check the switchover time, keep the unit charged, and tell your supplier and utility that you rely on medical equipment.
Can I take a power station on a plane for my CPAP?
Almost never. US rules limit lithium batteries in carry-on bags to 100 Wh, or 160 Wh with airline approval, and nearly every power station is larger. Most CPAP makers sell smaller approved travel batteries for flying.
How we worked this out: CPAP power figures are typical values for current machines; nights per charge are calculated with an 85% usable-capacity assumption and 8-hour nights, not measured on specific products.