Our WFCO died in it's 3rd season. It tripped the 120 volt breaker and I could smell overheating wire. It also killed the battery. I *think* the WFCO never did charge the battery properly from new as it never seemed to keep a charge very long at all. They are known to overcharge and boil out batteries and often don't go into bulk charging mode. You can read the stories about them being garbage but may not believe them until it happens to you. If you were to see a PD unit beside a WFCO, you'd be amazed at just the physical difference alone.
You might also try checking the ground and positive connections between battery and charger/converter including mini-circuit breaker. Using a voltmeter and with battery disconnected, what voltage is the charger showing and same with battery?
After replacing our WFCO converter with a PD unit and upgrading to an AGM battery, I also installed an LED voltmeter so I can regularly keep tabs on the voltage.
