Our 20-year-old Class B had a really bad battery life even when as fully charged as the old MagneTek 6330 and Ford alternator could get it. I was convinced that I was going to have to add another battery AND solar.
But last month I swapped in a Progressive Dynamics 4645... a semi-drop-in (same form-factor, but wrong wire placement) with better management AND desulfation.
Last weekend we took a three-day boondocking trip. A bit of generator run for AC, but mostly battery only. Plenty of juice the whole time. The reconditioning of the battery and the more effective charging may have eliminated the need for more capactity and a solar panel! Here's hoping!
Thanks Don. Solar is on the fantasy list, but the RV acquisition-and-repair cost still is under $10K and the bluebook around $2500, so I'm not sure there's much sense putting $600+ into solar if it's not going to be a big win for us. That's money DW would be loath to see go to something of nebulous benefit.