Charge spare battery

ktmrfs wrote:

K_and_I wrote:
Thanks again for the replies. They are Resmed CPAPs and use 24 volts. We do plan to turn off the humidifiers- that is the basis of the calculations I used to size the battery. Things may change in the future, but for now, I just need 1 night's worth of use at a time. We do not boondock for more than 1 night without a plug in between.

ok battery power solutions makes a 12 to 24V dc to dc converter for the resmeds. BTW the resmed ONLY runs on 24VDC ALL the time, the wall plug brick converts 120V to 24VDC. cost of the bps converter is around $50 IIRC. Once you turn OFF the humidifier AND use airplane mode, the resmed will draw less than 1A. that's 8AH or less per night. even with two at 16AH/night and a single 75AH battery you should be able to go 3-4 nights before needing to recharge.

ResMed also makes 12v DC to 24v DC converter (brick with cable that connects to CPAP) that comes with two different cables to connect between the brick and 12 volt source. One cable has battery clamps the other has a cigarette lighter plug. My medical equipment provider kept telling me that insurance didn't pay for it. At the time I had an Anthem EPO (premium) plan that provided 100% payment on medical equipment. I contacted Anthem and they said they would pay for the converter under my plan since I had 100% coverage provided I had a note from the doctor saying it was necessary. I told respiratory doctor I needed it when I went camping and he provided the note on a prescription pad for me which I turned in. Insurance paid for it. I Have used it on trips with 6 hours sleep per night for 3 nights using the humidifier. I used a spare Walmart group 27 EverStart 27DC deep cycle battery used for CPAP only. Still showed over 12 volts on the battery after I got home. So it would probably last me 4 nights at 8 hrs per night or 6 nights at 6 hrs per night.