Have been running my MPPT 100/20 for about 1.5 years without issue on my travel trailer. We are out on a trip now & I noticed one morning no charging & a fault #21.
I unplugged everything & replugged...worked fine. Next morning...same thing but went back to fault some time during the day...then I reset again... next morning no fault but was seeing battery bounce between negative amps & 0 at the MPPT battery with a bulk charge. When I disable charger (off state) & re-enable, it faults. Wont charge at all now.
Thankfully I'm at a plug in site for a week so don't need solar...but whats going on? Faulty MPPT?