DIAGNOSIS The MPPT solar charge controller is stuck in a loop. This can happen with certain third-party solar panels or prolonged float charging where the voltage fluctuates around the cutoff point.
FIX Disconnect all inputs and outputs. Press and hold the power button for 15 seconds to force a full system reboot. Reconnect only the AC adapter to see if it recognizes a full charge and stops. This usually clears the controller logic.
IF THAT DIDN'T WORK Drain the battery below 95% by using the unit to power a light or fan for 15-20 minutes. Then try AC charging. If it still shows constant "charging" at 100%, the battery management system (BMS) has a faulty voltage sense circuit.
HEADS UP Never leave the unit connected to solar panels indefinitely without a load. The constant trickle can confuse the BMS. Use panels with an open-circuit voltage (VOC) between 12-28V for the Explorer 1000.