14 36LA Chassis battery drain
Our rig was impacted by a nearby lightning strike a few months ago. Most items have been repaired, but some still linger. The latest that shouldn't be related, as far as I know, is that the chassis battery will drain overnight while camping and on shore power. I've been able to use a battery boost to start it, and we get to our destination and get set up ok, but within a day or two, the chassis battery voltage is too low to turn over the engine.
Yesterday, I took the battery to O'Reilly's to have it tested. It is just over a year old. I think it was at around 10.8 volts when I dropped it off, and the quick test indicated it needed to be fully charged and tested. This was done in about 2 hours, and I was told the battery was fine.
I returned to the campsite and installed the battery (12.45v). This morning, I figured I'd check the battery voltage just to see how it held overnight after a full charge, and it is down to 8.75v. Is there something I'm missing that can be causing the battery to drain? Is there supposed to be a trickle charger when on shore power? I never had this problem before the lightning strike and before it was taken to a repair shop for multiple engine electrical parts replacements (including ECM and ABS controller).
2014 Tiffin Allegro Open Road 36LA