Sizing backup power for a CPAP

This page estimates how much energy a CPAP setup draws so you can compare options. It is not medical advice, and a portable power station is not a medical device.

The humidifier is the whole question

Most CPAP machines draw somewhere around 30 to 60 W at typical pressure settings with the humidifier off. Turning on a heated humidifier, and especially a heated tube, can roughly double that figure.

This is why a single default number is useless. Two people with the same machine and the same pressure setting can need meaningfully different capacity depending on whether they use heated humidity. Ourcalculator lists those as two separate devices rather than one guess.

Estimating your draw

Your machine's label or manual usually states a maximum amperage at a given voltage. The maximum is a worst case, not your typical draw, but it is a starting point. Manufacturers sometimes publish average consumption figures at specific pressure settings, which are more useful.

• For an eight hour night at an estimated 45 W average, plan on roughly 360 Wh of energy.
• The same night with a heated humidifier at roughly 80 W is closer to 640 Wh.
• Apply a reserve margin on top. Cold rooms reduce usable battery capacity.

What a power station is not

Equipment manufacturers sell battery modules intended for their own machines, with documentation covering compatibility and safety. A general purpose power station is a different kind of product. Some machines will run from one; others behave badly with a modified sine wave or with the standby draw of an inverter that never fully sleeps.

Before you depend on any battery for therapy, confirm three things with your equipment provider: that your specific model tolerates the power source, whether your humidifier should be disabled to extend runtime, and what the manufacturer recommends for outages. That conversation is worth more than any estimate on this page.

What the verified catalog covers

These are not therapy ratings. They are the smallest models whose nameplate capacity and continuous output cover the estimated loads above, after inverter loss and reserve. There is no motor start in a CPAP load, so surge is not the constraint. Confirm compatibility with your equipment provider before you rely on any of them.

Testing before you need it

The only way to know your real runtime is to try it on a night when a failure is harmless. Run the setup at home, note how much capacity the battery reports in the morning, and use that instead of a published estimate. Our figures are calculations from power ranges, and your machine, mask fit, and room temperature will all move the result.

Next:run the CPAP rows in the calculatoror readhow to size a solar generator.