Electrical Help Please

:popcorn: I have the same type issue. Check your grounds and the way the trunk mount battery is wired. That was my issue, I think. I'm still doing other things and am waiting for warm weather.
I think if you disconnect negative while running, it should stay running? If it dies, some type of charging issue? IDK but someone will correct me.
67Dart273 will chime in. He knows his stuff.