Resurrecting this thread for an update. After 7 years the battery crapped out, possibly precipitated by the failure of the solar charging circuit due to a shorted battery connection at the controller (fused so no other harm) & a bad diode on the solar feedline.
Replaced the battery then troubleshot the solar charge circuit. Ended up replacing the controller & cleaning up battery & panel feedlines (blocking diode no longer needed). Everything back to proper function again.