CPAP overnight, humidifier off
What size battery runs a CPAP for one night without a humidifier?
A CPAP running dry draws far less than most people assume. The number that decides the purchase is a full night of hours, not a peak wattage, and the humidifier setting changes it more than any other choice.
The answer
- Battery to shop
- 542 Wh
- Daily energy
- 384 Wh
- Startup surge
- None
- All devices at once
- 57 W
Nameplate capacity, after inverter loss and a 20 percent reserve, for 1 day.
2 devices after duty cycle, before conversion losses.
No motor or compressor in this load, so there is nothing to clear.
Continuous output the station has to hold if nothing is staggered.
No motor start is involved here, so capacity alone decides the answer. Surge and continuous output are effectively free.
The load, row by row
| Device | Watts | Hours | Duty | Wh per day |
|---|---|---|---|---|
| CPAP / BiPAP (humidifier OFF)Eight hours is the usual night. Your pressure setting moves this. | 45 W | 8 h | 100% | 360 Wh |
| Phone chargeOne phone charge, for scale next to the machine. | 12 W | 2 h | 100% | 24 Wh |
| Total | 384 Wh |
Duty cycle is the share of each hour a device actually draws power. A compressor fridge cycles, so its average draw sits well below its nameplate.
What this load needs from a station
- Capacity.At least 542 Wh of nameplate capacity, which is 384 Wh of daily draw divided by 85 percent inverter efficiency and multiplied by a 1.2 reserve.
- Continuous output.At least 57 W if every device runs at once, or less if you stagger them.
- Startup surge.Nothing to clear. This load has no motor or compressor, so a peak rating is not the constraint.
- Solar, if you plan to recharge off grid.About 90 W of panels to replace a day of draw in 5 peak sun hours. Check the station's published solar input limit, because a larger array than it accepts is wasted.
Verified models that cover it (54)
Smallest adequate model first, since the useful answer is the least you can buy that clears every limit.
EcoFlow RIVER 3 MaxSmallest that fits572 Wh / 600 W · boost only · 30 Wh spare
Jackery Explorer 600 v2640 Wh / 500 W / 1,000 W surge · 98 Wh spare
BLUETTI EB70S716 Wh / 800 W / 1,400 W surge · 174 Wh spare
BLUETTI AC70768 Wh / 1,000 W · boost only · 226 Wh spare
EcoFlow RIVER 2 Pro768 Wh / 800 W / 1,600 W surge · 226 Wh spare
46 models in the database publish a resistive boost rating instead of an inverter surge, so they are not counted here. Their capacity is still listed on their own pages.
What to cut if nothing fits
If the recommendation is larger than you want to carry, reduce hours before you reduce the machine. A four-hour night is not the plan.
Questions
How many watt hours does a CPAP use in a night?
A machine running without a heated humidifier sits in the 30 to 60 watt range, so eight hours lands near 360 watt hours before conversion losses. Heated humidifiers and heated tubes roughly double that.
Does a CPAP need a surge rating?
No. A CPAP has no motor or compressor, so there is no startup surge to clear. Capacity and continuous output decide whether a station covers a night.
The formulas and constants behind every figure on this page are documented on themethodology page. Source URLs for the specifications sit on eachmodel page.