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How Long Will a CPAP Run on a 500Wh Power Station?

A typical CPAP without the heated humidifier draws about 30–40W and will run for 10–14 hours on a 500Wh power station — enough for one full night with margin, and sometimes two nights if you're a light user. Turn the heated humidifier on and draw climbs to 90–120W, which cuts runtime to 4–6 hours (one night, no margin).

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The Math, Worked Out

Formula: (Battery Wh × 0.85) ÷ Device watts = Runtime hours

Battery: 500 Wh

Usable after 15% inverter loss: 425 Wh

CPAP running draw (no humidifier): 35 W average

(500 × 0.85) ÷ 35 = 12.1 hours on AC.

On the 12V DC car-port output (bypassing the inverter): roughly 14–16 hours.

With heated humidifier at ~100W: (500 × 0.85) ÷ 100 = ~4.3 hours.

Variables That Affect the Answer

  • Humidifier setting. The biggest single variable. Off vs. high heat is a 3× difference in power.
  • Pressure setting. Higher CPAP pressures (15+ cmH2O) force the motor to work harder. Add 20–30% draw vs. low-pressure users.
  • AC vs. DC mode. Running on the 12V DC port saves ~15% by skipping the inverter. Cable adapters are sold by ResMed and Philips.
  • Ambient temperature. Cold air requires more humidifier heat to maintain comfort, raising draw.
  • Mask leak rate. Bad seal = motor compensates with more flow = higher draw.

Recommended ~500Wh Power Stations for CPAP

At exactly 500Wh the market is sparse — these three sit on either side and are tested with CPAP units. All three offer 12V DC output for inverter-bypass operation.

Jackery Explorer 300

293Wh · 300W · 500W surge

Ultralight 7.1 lb option for one-night trips. Pure sine wave AC, 12V DC port.

Check Price on Jackery

Bluetti AC70

768Wh · 1,000W · 2,000W surge

LiFePO4 with enough capacity for two full nights without humidifier. Great margin.

Check Price on BLUETTI

Anker SOLIX C800

768Wh · 1,200W · LiFePO4

Long cycle life and 5-year warranty — built for nightly use over many years.

Check Price on Anker SOLIX

Frequently Asked Questions

Should I run my CPAP humidifier off the power station?
No, if you want to maximize nights. The heated humidifier roughly triples power draw (30W to 90–120W). Turn humidifier off and use a hose with passive moisture, or accept ~one night per charge.
Do I need a pure sine wave inverter for a CPAP?
Yes. All modern power stations from major brands (Jackery, Anker, Bluetti, EcoFlow) output pure sine wave AC, which is what CPAP motors and electronics require. Avoid cheap modified-sine inverters.
Can I run my CPAP on DC to save power?
Yes — most ResMed AirSense and Philips DreamStation units have a 12V DC input that bypasses the AC inverter, saving ~15% energy. A 500Wh station on DC can deliver 14–18 hours of CPAP runtime instead of 10–14.
What size power station do I need for a week of CPAP use camping?
For a 7-night trip at ~250Wh/night (no humidifier, DC mode), you need ~1,750Wh of capacity, or ~500Wh + a 100W solar panel. With humidifier on, plan for 600Wh/night.

Want to run the numbers for a different battery size? Open the Runtime Calculator .