I use a CPAP and have the following set up:
1. purchased a marine deep cycle battery of 100w minimum.
2. obtained 12 volt harness for my cpap from manufacturer.
3. purchased a digital battery charger for shore power recharging after cpap use.
4. when battery is approx. 100% charged, I can get 3-4 cpap uses out of it before having to recharge.
5. it would unusual to use a cpap more than 6-8 hrs at a time.
6. rv generator will also charge battery if no shore power is available within 4-5 days.
Hope this helps.
Best of luck.
