When I was young and foolish and thought money grew on magic trees, I shelled out at least twice for batteries when I stupidly left my bass plugged in and found the battery was dead.
after those two occasions I learned not to do it.
I’m with @EBS_freak Are you sure you’re not overthinking a fairly simple problem? I mean unplugging a bass lead, thus isolating the battery is actually no harder than flicking a switch, thus isolating the battery.