So we have not plugged into shore power for 11 days and my house bank is taking a beating. dropped it down to about 35% yesterday morning pulled anchor and figured things should charge up nicely on the 4 hour planned trip. All the other batteries start1, start2, Bthruster, Sthruster and genny are all 100% as they are essentially disconnected from the house bank.

That being said, as we started moving along I noticed my USB charger read out at 11.3v?? This is not normal while underway. I went down into the cabin and verified my SOC meter. in a minute or so, it would go from +62 amps which would be normal but then dropped to -45a or so. It kept on doing this for the next 45 minutes until I decided to start up the genny to get the shore power charger kicked on. Well this solved the issue and after about an hour or so I shut down the genny letting the alternator take over which at that point worked as they always did. I should also mention the other batteries were charging fine during the entire weird event floating around 13.9 to 14v while under way.

Another thing, I have dual 135 amp alternators, I would think with a large 435AH depleted house bank I should be charge quite a bit more than 60amps.

What happened? I am certainly at a loss. Only thing I can think of is the isolators do no like a severely low battery? Something is not right and am leaning towards the isolators. Any suggestions before I start discarding good stuff.

Are heading to a Marina today to do laundry and fill water and a much needed over night charge.