A power outage at 3 AM shouldn't mean missing a night of therapy. The good news: keeping your CPAP running on battery is simpler than most people expect, and you don't need to spend a fortune.
Here's what actually matters when picking a CPAP battery backup.
What your CPAP actually needs
Most CPAP machines draw between 30 and 80 watts with the humidifier running. Without the humidifier, that drops to roughly 5 to 30 watts depending on your pressure setting.
That matters because a battery rated at 100Wh (watt-hours) will last:
- About 1.5 to 3 hours with the humidifier running at 30-50W
- About 5 to 15 hours without the humidifier at 5-15W
Turn off the heated humidifier during outages and you'll easily double or triple your runtime.
AC vs DC: the most important decision
Your CPAP can usually run two ways from a battery:
AC (through an inverter): The battery converts DC power to AC, your CPAP converts it back to DC internally. This conversion loses 10 to 20% of your battery's capacity.
12V DC (direct): If your CPAP machine supports a 12V DC input (many ResMed and Philips models do), you skip the conversion entirely. You get more runtime from the same battery.
If your machine supports 12V DC, use it. Most CPAP-specific batteries and travel power stations offer both options.
Three types of CPAP battery backups
1. CPAP-specific batteries
Batteries built specifically for CPAP use. Examples: Medistrom Pilot-24 Lite, ResMed Power Station II, HDM Z1 PowerShell.
Best for: reliability, FAA carry-on compliance for travel, built-in 12V DC support for compatible machines.
Downsides: more expensive per watt-hour, often only work with one machine brand.
2. Portable power stations
General-purpose batteries with AC outlets, USB ports, and sometimes 12V DC. Examples: Jackery 240, EcoFlow River 2, Bluetti EB3A.
Best for: flexibility — they work with any CPAP and anything else you need to power during an outage.
Downsides: heavier than CPAP-specific batteries, AC-only models waste some capacity through conversion.
3. Large lithium power stations
Higher-capacity units (500Wh to 2,000Wh). Examples: Jackery 500, EcoFlow Delta, Bluetti AC200P.
Best for: multi-day outages or camping trips where you need power for more than just your CPAP. For trail camping where weight is the priority, see our CPAP backpacking guide instead.
Downsides: expensive, heavy, overkill for most power outages.
How much capacity you actually need
A rough rule for planning:
| Hours of sleep | Pressure setting | Without humidifier | With humidifier |
|---|---|---|---|
| 8 hours | Low (5-8 cm) | 40-80Wh | 120-200Wh |
| 8 hours | Medium (10-14 cm) | 80-150Wh | 180-280Wh |
| 8 hours | High (15-20 cm) | 120-200Wh | 250-350Wh |
For most people at average pressure settings, a 100-150Wh battery gets you through one night without the humidifier. For two nights of backup, aim for 200Wh or more.
What to look for
Capacity (Wh): More is better. Don't buy less than 100Wh for a single night of backup.
12V DC output: Look for a 5.5mm barrel connector or a car-style 12V port. Check your CPAP manual to confirm it accepts 12V DC input.
AC output: Any unit with a standard 120V AC outlet works with your CPAP's existing power supply.
FAA compliance: If you travel by air, batteries up to 160Wh are generally allowed in carry-on bags. Over 160Wh requires airline approval.
Weight: CPAP-specific batteries are typically lighter (under 2 lbs). General power stations run 2 to 8 lbs.
Bottom line
For a basic power outage backup, any portable power station with 100Wh or more and AC output will work with any CPAP machine. The Jackery 240 and EcoFlow River 2 are reliable mid-range picks that double as camping power stations.
If you want maximum runtime and your machine supports 12V DC, a CPAP-specific battery like the Medistrom Pilot-24 Lite is worth the extra cost.
Turn off the humidifier during outages and you'll get far more out of whatever battery you buy.
