67 Barracuda Heavy Electric Load

DallasMan2000 said
The wiring harness was replaced a few years ago. I said it is “factory” because my understanding is that the replacement wiring is “factory like”. I bought the car last summer and it has lots of upgrades and I am sketchy about many of the details. The Hanmetek meter I purchased on Amazon reads DC volts but it might also read amps - not sure about this.

The issues I mentioned are the NUMBER ONE list you MUST address. You HAVE to figure out if the wiring is large enough or not, PERIOD. There is no possible way to get enough current through a bulkhead connector without melting terminals, etc. There is NO possible way to get that much current through a factory style ammeter.

Your low running voltage could very well be related to this if that is true.