Okay, if anyone's interested, I found f-5, a 5-amp fuse blown on the control board. It is the aux start fuse, which is for sure why I couldn't get the house batteries to help me start the engine, but I have no idea why (or if) it had anything to do with the lack of charge of the chassis battery from shore power.
When I replaced the fuse, the chassis battery started charging, though.
May have been an air bubble in the line somewhere.
I'm certainly going to keep an eye on it though! Gonna do a shakedown cruise to the Kern River next week, a 120 mile trip with some really steep, winding mountain roads. We'll see what else we can find!
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2005 Georgetown 342DS XL, Full Banks Package
2005 Liberty Renegade 4X Toad
1989 Wrangler Sahara Toad
1984 19.5' Beachcraft i/o 5.o liter, 4-bbl (and you thought your Moho sucked gas!)