Had a fuse between mppt and solar panels but not sure why but didn't work. will figure that out later BUT can I replace the internal fuse on an MPPT 100/50? I believe the polarities were crossed and that's what did it.
asked
MPPT internal fuse replacement
A fuse can not protect against reverse polarity. It just protects against catching fire (by breaking the circuit).
Most likely your charger is damaged (not just the internal fuse) if you connected the battery with reverse polarity.
