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Tequila's avatar
Tequila
Explorer
May 05, 2014

CPAP and battery power

My old RV had invertor output next to the bed, the new one does not and there is no handy spot to tap 12V. My idea is this. Buy a 120V relay with double throw 120v contacts. Remove the 12 volt feed from the back of the convertor that feeds the bed plugs. Buy a 1000 watt invertor and wire it through the relay such that when there is 120v shore power, the relay powers up and switches 12Ov to those plugs. When 120v is not present, the relay goes to its resting position and switches 120V output form the invertor to those plugs. The 2 bed plugs are on their own circuit

I have plenty of room behind the convertor box to accomodate the relay and the invertor.

Anyone see an issue with this?

14 Replies

  • and if you use a pass over humidifier, rather than a heated one, your power needs will be minimal.
    bumpy
  • Sounds like an awful complicated solution to what may be a simple problem. Most CPAPs sold today operate on 12vdc or 24vdc. Both have an adapter/plug that allows operating from a 12vdc circuit.

    If your CPAP is one of them, buy the 12vdc adapter and plug into the 12vdc system of your RV. What voltage does your CPAP really need? Look at the label on the back.
  • Are you sure you need the inverter? My CPAP runs on 12V, although I did have to buy a special !2V cable for it. I'm new to CPAP, but have read that most of them run on !2V; 12V is produced by the big block thing on the 120V cord that comes with the machine. By running straight from 12V, you are cutting out the inefficient middleman, the inverter.
  • If 'resting position' is with the other contacts closed, that will work.

    It would be easier and likely safer to just keep the inverter on battery 24/7. When shore is present it will be charging batteries.