Originally Posted by toskeysam
That's exactly what I experienced last winter. The solar output in really crappy days....lots of them in the mountains in winter....did not keep coach batteries up to a switchover point. I found my chassis battery very low.....
At the risk of getting a bit too much thread drift, that's exactly why I brought up the subject in my "crazy idea" thread. Some of the good folks here seemed to think that adding a dedicated solar panel for the sole purpose of keeping the chassis battery charged wasn't necessary, but the more I watch my coach's parasitic draws siphon the juice from my house batteries, the more I think I'm going to need to address this (in the other thread of course....
Back to the OP's conundrum, if you have shore power while in storage, it really doesn't matter what battery bank you connect your alarm to. If you don't have shore power, and your rig is stored outside, then shark's idea of a standalone aux battery tended to by a dedicated in-window solar panel may be a solution. You'll need to do some math to figure out battery size based on alarm draw and also size your solar panel appropriately, taking into consideration days of sun at your rig's locale, etc.