This is a 1969 Dodge Charger 318 automatic. I converted to a newer style alternator and electronic voltage regulator. When I finished with the conversion, with the engine running it was showing 13.8 volts at the battery terminals, which seemed to indicate that it was charging fine. A couple days later however, it didn't seem to be charging properly. Sometimes it would show about 12.5 volts at the battery while running, and other times it would get up to about 12.9 volts. To get up to 12.9 volts, it has to be charging somewhat, perhaps intermittently, but it doesn't seem right.

I'm showing good continuity between the electronic regulator's outer metal case and various ground points on the car (e.g., engine block, firewall, negative battery terminal), so that's not the problem.

The car's alternator gauge seems to be showing intermittent activity. While idling, sometimes the needle stays dead center, and other times (usually when I rev the engine, but not always), the needle advances to the right some.

I followed this wiring scheme:



From this site.

One thing I wondered about when rewiring it: on the stock mechanical regulator setup, there were two wires that went into the quick-disconnect terminal that pushed onto the driver side of the voltage regulator (ignition terminal), one black / dark colored and one black / dark colored with a white stripe:



Now, according to the instructions and the diagram, you remove the wires that connect to the old mechanical regulator and splice them together, and also splice in the center wire of the new plug. The instructions only mention two wires (ignition and field, for a total of 3 wires being spliced together when you add in the center wire of the new plug), but I have 3 wires there, 2 going into the ignition side and one into the field side. So I ended up splicing a total of 4 wires together (the 3 that went to the old regulator plus the center wire of the new plug), like so:



Was that the right thing to do?

I've heard that the car's alternator gauge is a critical part of the charging circuit, so if something is screwy with that, it won't charge properly. I was thinking about adding a jumper wire across the two terminals of the gauge to eliminate that potential problem (any thoughts on this?). Are there any other parts of the charging circuit I should test?

You're wired correct. I'd go thru the basics again then see where you're at: batt in good shape (& all charged up/no bad cell), alt brushes etc tight (take em out & look at them), positive/neg circuit sides clean/tight/low resistance (you've checked the neg side). seperate/clean the bulkhead brass terminals (a small metal bristle brush on the male ones/NAPA 725147 brass male terminal to clean the female ones)

i had the same problem, it was a bad voltage reg., it was brand new no miles and was bad, they do not make them like they use too, i also had a ground problem, until i run a ground wire from the motor ground over to the voltage reg. housing,

Usually a bad batt or one that has a bad cell will make the rate go high as it tries to force the (bad) batt to accept a charge. Kick it up to a fast idle & turn on the a/c/headlights & see what you get at the alt and at the batt (when it's fully charged up).