I am suprised that you had issues with 10 awg wire. My two solar chargers are wired to the battery using 8 awg wire. I had no issues whatsoever inserting the wire into the solar controller. (View Post)
I would add that having the solar charger closer to the battery is more efficient. My Victron MPPT charger is a couple of feet away from the batteries and I put an external port (MC4 connectors) in t… (View Post)
And you just hit the nail on the head with the biggest problem. If you never charge a LiFePo4 battery to 100% then you are asking for problems. (View Post)
If you swapped out the batteries for a 12v and everything worked fine, then along with everything else that you are describing you have faulty batteries. (View Post)