ResMed S8 Elite II and Battery (camping)

I have been on CPAP for 2 months. I have researched and read with great enjoyment that I will be able to camp this summer with the proper equipment. Well, this weekend I took the first trip of the season in our camper ('67 Terry 14'). I bought the converter for the S8 Elite, installed a new 12V outlet, and bought a new battery for the camper (Exide Nautilus HD-M-24 Marine from Checker Auto). The trip was four nights. The first night was short in an RV park (6 hours on CPAP)...lasted the night, no problem. The second night the converter cut out just before sunrise (due to the cut-off-of the converter at about 9.5V on the battery). I charged the battery the next day direct with a generator and did not make it through the night. The next night was the same...not sure of the time (it was still very dark!) Questions are...did I buy the right battery, do I need to daisy-chain two batteries together, did I charge enough, what do I have to do different next time I camp? I thought I researched it all, but I still had my family and others complaning about the snoring...not to mention my lack of "good" sleep while enjoing time with my family. Thanks for all of the techies out there that have figured this out. Thank you for your help. Camping season is here for us "hoseheads"!

RalphMalf wrote:Exide Nautilus HD-M-24 Marine

You bought an Exide Nautilus Marine Starting Battery, which is NOT what you need. A starter battery is designed to delivery high current for a short time and normally should not be discharged below about 85% to 90% of capacity. In terms of the Exide range, you would have been better off with a Exide Nautilus Marine Dual Purpose Battery.

You need a battery which is able to consistently supply a lower current over a longer period of time (that is not a starter battery) and which you should not discharge below about 50% of capacity if you want good life out of the battery.

Cheers,

Bill