1966 dart problems, help

According to your photos the alternator looks like a standard issue 66 Dart unit.
The regulator looks like a standard issue 66 Dart unit also but it could be an electronic regulator. I installed a electronic regulator that looked exactly like a old point type and it boiled my battery and burned almost every bulb out of my car. It was charging at 17+ volts also. I replaced the regulator with the old point type that came with the car and replaced the battery (and a whole bunch of bulbs) and everything is good. I think I had a bad ground with that electronic regulator that caused the alternator to full field or charge to the max. output. A bad battery with a shorted or dead cell could also cause the problem. If a battery is showing the alternator a discharge, it will over charge to try to compensate. I would replace the battery and the regulator making sure all the grounds (including where the regulator screws into the firewall) are good and then test the alternator output. Mike