Electrical gremlin? Wouldn't wish that on anyone, but I've dealt with a similar issue. Turned out to be wiring problem. Once old wires with poor insulation got hot enough, resistance went way up, charging system stopped working, battery went dead. Doesn't sound like that's what you're dealing with, at least I'll hope it isn't. Little buggers can be difficult to track down.
Oh wait, people are already suggesting something similar.
Last edited by BusterBoo; 06-20-2019 at 01:44 PM.
Reason: people already pointed to this potential issue