I set up a 12v system in a camper van over a year and a half ago with a 175w solar panel, SmartSolar MPPT 100/30 controller, BMV-712, and a 50ah Battleborn. Ran great with no problems. Two months ago I added another 50ah battery in parallel, ran great with no problems. It has been very hot recently and temps have been getting over 120 F in the van when parked. I started to notice that my vent fan was beeping, but didn't think much of it until my fridge had completely shut off but my lights still worked. I then noticed that the charge history showed my battery's voltage maxing out at over 20v for a week and that that no watts from solar charging were recorded for the previous 5 days.
My charge controller just keeps showing the flashing bulk light indicating "no charge". Even in full sunlight with my panel's vmax coming through, but no current or power according to the charge controller app. Strange thing is that the unregulated panel voltage seems to be making it past the charge controller. If disconnect the panels and charge controller, the battery voltage will eventually stabilize. I am assuming the BMS on my batteries has kicked in to stop charging, but my loads must have been getting the PV voltage direct. Hence the fan beeping and turned off fridge.
Other weird part it that in direct sunlight, my battery monitor will register watts coming in but the charge controller wont and maintains the flashing bulk light. In full sunlight, the BMV will record 21v. I have a breaker between PV panels - charge controller and charge controller - positive bus bar. Testing voltage on both sides of breakers and they seem to be functioning properly. Not sure if high temps could have done this, but my system has functioned without issue for a while prior to this.
Any help would be appreciated.