Double, double, boil and trouble.
This week's problem started last week with a smell. I initially thought it was a waste water smell, but couldn't find anything. Turns out the rear starting battery was being boiled dry. Not good. This, of course, happened while I was on the road. I bought a battery to carry as a spare because the starting battery(ies) still worked, but wouldn't last long.
Made it home, but the batteries were toast the next morning (second time this year it's broken down in my garage--at least it's trying). Figured the problem had to be my new 270a, DC Power alternator, but discovered it would also boil them with the engine off and on shore power. I measured charging voltage on both the starter and coach batteries--both normal--and discovered the separator didn't seem to work on occasion and was getting warm even while the engine was off with no shore power. Replaced the batteries and separator, so far it seems fine, but I'll be sniffing around it for a while.