So I found this:
https://shoraipower.com/products?act...99&year=381999
Shorai Batteries require a charging system output of 13.1 Volts or higher at idle, and must not exceed 15.2 volts at maximum output.
I've seen 15.3 VDC and I bet that's what the "Battery Error" I received is. I bet my reg rec is gonna take a dump... or.. it's heat related.. I commute and where I park there is no shade. It's been in the 90s... Kansas sun... beating down on the seat... reg rec is under the panel with the key lock for the rear seat. I bet it gets hot AF under there.