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robertj1961 · 01-23-2023, 01:37 PM

Good information. I would agree about the possibility of solar supplying the 5.2 volts if it was showing that without the AC cord hooked up to the 30 amp source. The only time I would get 5.2 volts was when plugged in which I thought very odd. When it was unplugged, no BMpro power or Mastervolt power. No DC anywhere. I looked at the lights on the Combi and all dark with no power to the inverter unless plugged in.

The Thor Tech seemed to think my 250 amp Big Boy fuse had blown. That just shows how little they know about these. If the DC didn't come back on however that is where I would start I suppose. There is also a 50 amp fuse located near the Big Boy fuse that is resettable and not sure what that one does but it had not tripped.

I think you and DavidEM are 100% correct about the RELion BMS shutting everything down DC. I suppose when that happens it does not supply any DC until it resets and not sure how long that takes or if it has to warm up before power comes back?

The only other thought I had when plugged in was the 5.2 Volts possibly related to the battery heaters? I should have just have left it plugged in for an hour or so to see if it reset and started working normally I suppose but didn't have time that day to deal with it. It seems stupid however that the Relions would not supply any power at all while heating. I get the reason for not charging until heated but once they shut down like they did forget about any power for a while. That would suck if I was camping somewhere because no heat or warm water would be available either.

I really need to figure out how to drop the battery boxes and disconnect the power from there but looks like it could be a pain.

For now, I am fortunate to be in North Carolina and will not try and charge the batteries when cold. I am afraid however this will happen again anytime below 41 degrees and that is unacceptable IMO. I would think generator and shore power should react the same but this may be possibly just related to the Onan generator and hope that the case for all those with the UHG.

The MV was set to draw 25 amps when this happened with the generator so I don't think that could be the cause but anything is possible...

Happy to have others around who understand the electrical side of all of this much better than I do and thanks for replies! I am all about "trial and error" but try not to repeat the same mistakes twice. Pretty obvious Thor also engineers with "Trial and Error" rather than testing all of this ahead of time.