What Size Inverter to Run a CPAP Machine?

Answer
300 W pure sine · 60 W surge

A typical cpap machine draws about 60 W. Size the inverter for at least 300 W continuous. At 12 V it pulls about 6 A from the battery.

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W
Everything on at the same time.
W
Largest motor only: fridge ≈ 1,000–2,000 W.
%
Inverter size
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How we calculated this

    For estimating and educational purposes only. Results are approximate and are not a substitute for a licensed professional, the manufacturer's instructions or your local code. Disclaimer

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    Why this size

    Without the heated humidifier; with it, CPAPs can draw 90 W or more. We size the continuous rating at 125% of running watts and check that the surge rating (usually about twice the continuous rating) covers the startup.

    Value
    Running watts60 W
    Surge needed60 W
    Battery current at 12 V6 A
    Battery current at 24 V3 A

    Frequently asked questions

    How long will a 100Ah battery run a cpap machine?

    About 16.2 hours from a 12 V 100 Ah lithium battery at a steady 60 W (less for cycling appliances, more for intermittent ones).

    Do I need a pure sine wave inverter?

    Yes for motors, compressors, medical devices and modern electronics.

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