Doing a DIY van conversion and ran into trouble after COVERING the van (yes, I have a very large cover to tuck the van in when we have to take an extended break) but NOT shutting the house electrical system down (I know, dumb).
When we uncovered the van 5 weeks later, van battery was completely dead, FINALLY got it jump started, but now have very weirdly behaving house batteries (lithium). They appear fully charged, but don’t maintain their charge when I turn anything on, unless we also have (a) full sun, (b) van turned on, or (c) shore power plugged in.
We are thinking it is related to the isolator charging the house batteries from the alternator while the solar panels were covered with canvas. (In case it matters, we do NOT have a “smart” isolator.) We assumed that the isolator would stop the draw from the van batteries, but maybe it didn’t? That would explain the van battery being dead, but did it also ruin the lithium house batteries? And how does one figure out if lithium batteries are ruined if they say they are charged 100% but then jump up and down in volts and then stop working as soon as anything is turned on?