Ken, I suspect that the reason many coach engine batteries do not stay
charged well in long term storage is that SOMEWHERE in the coaches history,
SOMEONE has wired accessories into the engine battery that slowly drains
them. Modern DIN radios with electronic preset frequencies and power amps
are a frequent offender, as are charging docks for remote controls, GPS
navigation stuff, etc. My 78 Royale, which is bone stock, can sit for 2 to
3 months and still start on the engine battery. Just the Isolator, no
combiner. I do leave the coach plugged in, as I leave a small heater
running inside to keep it from freezing water pipes, etc. I leave the
Refrigerator on all the time as well. Here in Oregon, we use our coach
pretty much year round for rallies and camping. I replaced the old buzz box
converter after it toasted the first set of 6 volt T-105 Trojans I had. I
now have a smart charger Progressive Dynamics converter. It came with the
"charge wizard" as an accessory. I also replaced the toggle breaker with an
automatic transfer switch so I don't have to get down on my knees between
the beds to switch the toggle breaker when I go from generator to shore
power. The transfer switch has a timed delay that senses when the generator
voltage and frequency is stable before it switches over, a good feature if
you have a cranky generator.
Jim Hupy
Salem, Or