My 100/50 has been working fine for over six months. Recently I noticed through the connect app that the batteries had failed to charge for a few days. Looking at the controller it was not charging even though it was sunny day. The PV voltage was showing at 12.6. I disconnect the solar inputs and measured 19.8 volts coming from the panels. reconnected the input to controller and back working. This has happened twice now and this time controller is saying 6v and I can't get it to charge. Any thoughts?