Need help trying to figure out multi setup. This is my first install of a battery bank with a inverter/charger. There is much to be learned , so thank you in advance. I installed my multiplus 12v/3000/120v with 2 chins 300AH batteries and have a BMV 712 and Ve Bus dongle to read info. First night testing it was running in inverter mode and did not appear to be charging batteries, but seemed to be letting passthrough power through. I check it in morning and it was flashing low battery ( not sure why it was using battery when shorepower is passing though). So when I switch off battery cutoff multi will have a solid low battery light and no passthrough power is present. I test voltage and get 120v on ac in and 80v on the ac out. I am not even sure where to begin.