65 Ammeter now shows overcharge when accelerated

I was over there today to some work on my 86 Reliant and I started the Valiant up and let it run the whole time I was working on it. The ammeter seemed to settle in the middle after probably 30 mins. So definitely if driving this car a good many miles away it maybe wise to bring an extra battery and of course fire extinguisher. I've heard about the ammeters melting because of all the current going through them. It was one reason I replaced the dash harness and engine/light harness. It was amazing that the tail lights, dome light didn't work but headlights did while all this was going on and the only thing I could find wrong was the headlight switch securing bezel was loose. I guess it grounds it? I thought it had something to do with my alternator. I tigthened the bezel up, tail lights and dome light come on. It's almost ready to take a drive out in the public streets now.