[Equipment] Need advice for battery

[Polo 1955]

I run my Cpap a Resmed S9 Autoset in my camper with an Ecoflow battery and a 12-volt adapter found on Amazon that is 50 % cheaper than an OEM Resmed 12 volts adapter. Buying a used CPAP, for me is a good idea, a lot of ''tentative ''users of CPAP do not succeed and stop using their CPAP. It should be easy to find a machine with low hours. Also ''on the internet'' one can find tutorials on dismantling a CPAP, enabling complete device cleaning.