Originally Posted by HopCar
I use a CPAP machine when I sleep. I going on a houseboat cruise to Whitewater Bay next week for two nights. There is no generator on the boat.
The machine draws 1.5 amps of 110 volts to run. I have a 300 watt pure sine wave inverter.
Any suggestions on how to power this thing?
Lots of others have already provided most of what I'm going to say, but I thought I'd at least add a bit more detail from my testing and use.
I have a ResMed AirSense 10 CPAP with humidifier. When I got it a year ago, it was a life-changer. Not only did my partner not want to murder me anymore, but I now have 2x-3x the energy and stamina than I did before, which lets me do many more boat projects!
I live aboard about 50% of the year, so I use it both at home and on the boat. I did a lot of testing, being a DC power nerd, on both using it aboard, at home, and in power failure situations in both places. The last thing I want is to wake up pseudo-suffocating because I have no power...
I also have been (strangely) camping a bit more lately, and have taken it with me there as well.
I investigated portable CPAP machines and found them to mostly be a waste of money. Many of them have severely limited functions, and end up requiring more equipment to use in addition to your normal machine. For people who travel a lot on planes or trains and need to sleep there, they make sense. For a boat, not so much.
The CPAP branded batteries are also not a great investment. They seem to be purpose built for specific models in many cases, and limited overall amp hours. Again, for someone traveling a lot, these would make sense paired with a portable CPAP.
The biggest draw in the ResMed (and most others) is the heated tube and humidifier. Both are heated, and can account for more than 80% of the power draw. All of the more modern units have controls to turn this off, and will dramatically reduce the power usage.
With humidifier/tube heat on - around 300 watt hours in one night
Without - around 80 watt hours in one night
While camping, I use a Yeti 400 Lithium power station
to keep it running. I can go 3 nights on one charge of the Yeti, plus charging phones and other small things.
At home I also use the Yeti in case the power fails, but I leave the tube heater and humidifer on.
On the boat, I had been using the inverter via a normal AC plug, but switched to the 12v adapter a few months ago. I use the humidifier and tube heater on the boat because I have the power available.
The 12v adapter that seems more efficient than using the AC wall plug. I use this pretty much everywhere now because I'm using the 12v ports on the Yeti at home/camping, and a 12v socket on the boat. I would highly recommend getting that if you continue to use the CPAP off of a battery.