I have a Grand Design Solitude that is about 9 months old. We returned from a two week trip, did not dry camp, so the 5er was either hooked to the TV or on shore power for the two weeks. When we retur...
No worries with the Optima's as it appears most of your RVing is done with hookups. Not sure why your Interstate 12Vdc battery gave up the ghost so soon, maybe double-check converter output to ensure it is operating properly.