How long your CPAP really runs on battery.

Runtime figures with the assumptions stated — pressure, humidifier on or off, AC or DC. Retailers publish capacity; we publish nights.

• How long will a power station run a CPAP?

  A 1,000Wh power station runs a typical CPAP for about 98 hours — roughly 12 nights — with the humidifier off. Switch the heated humidifier on and the same battery gives about 20 hours, or 2.5 nights. The humidifier, not the machine, is what drains the battery.

• Does the CPAP humidifier drain the battery?

  Yes — dramatically. The blower in a typical CPAP draws around 8W, but the heated humidifier is a resistive heating element that pushes total draw to roughly 40W. Turning the humidifier off multiplies your battery runtime by about five.

• What size power station do you need for a CPAP?

  For dry therapy, budget roughly 65Wh per night — so about 200Wh covers three nights. With heated humidification, budget roughly 320Wh per night, which means around 1,000Wh for the same three nights. The humidifier setting changes the answer fivefold, so decide that first.

• Should you run a CPAP on DC or AC from a battery?

  Run it on DC if your machine supports it. Going through the AC outlet forces a double conversion — battery DC to AC, then your CPAP's power brick back to DC — which wastes roughly 10–15% of the charge. A DC cable skips that and buys about 12% more runtime from the same battery.

• Does a CPAP need a pure sine wave inverter?

  Use pure sine wave. CPAP manufacturers specify it, and essentially every current portable power station provides it. Modified sine wave can cause audible buzzing, heat in the power supply, and sometimes a machine that refuses to start — not a risk worth taking on equipment you rely on nightly.

• CPAP battery or portable power station — which should you buy?

  Buy a dedicated CPAP battery if the only job is the CPAP and you travel with it: DC-native, lighter, and sub-100Wh models are the simplest category to fly with. Buy a power station if you also need phones, lights or a router during an outage — it costs about 12% in conversion losses but does far more.