CPAP Backup Power: What You Need to Know
If you use a CPAP machine, a power outage isn't just an inconvenience - it's a night without sleep, and for many people, a genuine health risk. Sleep apnea doesn't pause because the grid is down.
The question isn't whether you need backup power for your CPAP. The question is how much, and what kind.
How much power does a CPAP actually use?
Most modern CPAP machines draw between 30 and 60 watts during normal operation. That's not much - roughly the same as a laptop. But the range matters because it determines how long your battery will last.
Here's the key variable most people miss: the heated humidifier. A CPAP without the humidifier running draws around 30W. Turn on the heated humidifier, and draw jumps to 50–60W. That's nearly double the power consumption, which cuts your battery runtime almost in half.
Runtime estimates
On a 1 kWh (1,000 Wh) battery:
- - CPAP without humidifier (~30W): approximately 25–30 hours
- - CPAP with humidifier (~55W): approximately 14–16 hours
- - CPAP with humidifier + heated tube (~65W): approximately 12–14 hours
On a 500 Wh battery (like the Ladegrid Apartment kit):
- - Without humidifier: approximately 12–15 hours
- - With humidifier: approximately 7–8 hours
These are conservative estimates. Actual runtime varies with your pressure setting, mask leak rate, altitude, and the battery's discharge efficiency.
What to look for in a backup battery
Not all batteries are created equal for CPAP use. Here's what matters:
LFP chemistry (lithium iron phosphate): Safer than standard lithium-ion, no thermal runaway risk, and rated for thousands of cycles. This is the only chemistry you should use indoors overnight while you sleep.
Pure sine wave output: CPAP machines have sensitive motors. A modified sine wave inverter can damage your machine or cause it to shut down. Make sure the battery outputs a pure sine wave - all Ladegrid kits do.
Sufficient capacity: If you need the humidifier (most people in dry climates do), you need at least 500 Wh for one night and 1 kWh+ for multi-night outages.
DC output option: Some batteries offer a 12V or 24V DC output that connects directly to certain CPAP models. This bypasses the inverter and improves efficiency by 15–20%. Check your CPAP manufacturer's compatibility list.
The humidifier decision
During an outage, you may want to turn off the heated humidifier to extend runtime. This is a personal comfort trade-off. Some people sleep fine without it; others wake up with a dry throat and nose that makes the CPAP unusable.
Our recommendation: test a night without the humidifier before you need to. Know whether it's tolerable for you. If it's not, budget for the higher power draw in your battery sizing.
What Ladegrid offers for CPAP users
The Ladegrid Medical Backup kit is built for exactly this use case. It includes an LFP battery sized for CPAP and similar medical-adjacent devices, a device and runtime guide, extension cables, emergency light, and a medication/device backup checklist. It's not a medical device - it's a power runway for the devices you already depend on.