It was not the system.

It died because it sat for 1.5 years dead.
It took a charge and held for a month.... but then my kids left the dome light on and it sat dead for two days and that was the end of it.

I charged it and it only achieved 10 volts... dead cell.
I opened it and two of the cells were low so I filled with distilled water.
When I charge it it smelled like sulfur.
It swelled on the charger overnight.
It was very hot.
I took it off the charger.
It remained hot for at least 10 hours. Even though it was in the shade.