Battery overcharging. Ignition box causing voltage drop at regulator

72 Dodge Dart Slant 6 Trying to figure this out. My amp gauge is high charge when running. Battery charges over 15v when revving. With motor off key in run voltage at battery 12.6. Voltage at ballist resistor/voltage regulator 11.4. If I unplug the ignition box connector which is on that same wire I get 12.6 at voltage regulator. Is this normal? A sign of bad ignition box? I put a ground wire from ignition box to battery. No change.

Nothing to do with your ignition box, not even sure why you went there.

The regulator is what controls the alternator output. Of course it needs good clean connections to work properly.

Unplug the voltage regulator connector when the engine is running, if the voltage stays at 15V there is a short to ground in the green field wire or internally in the alternator.

Been my observation that the voltage goes way past 15v with a short in the ground circuit.

Good idea to inspect the voltage regulator connection terminals. If in bad shape a repair harness is usually available in the AP store wiring or "help" section. Also a good idea to make sure the VR has a solid ground. Clean some paint off the housing under the screws and run a ground to the engine is in doubt.

Bad connections or bad ground can cause overcharge.

I think the reg is bad but first unplug the field terminals at the reg & confirm that neither male alt terminal is grounded & you might note how many ohms there is on that circuit & there is a spec for that & you spin the pulley by hand which woouldn't involve anymore than removing the belt for a quick test tho likely if the brushes & that circuit ain't grounded then the alt is good but it would be a good first step (& costs nothing). Do NOT run the eng any longer than 5 seconds at a time just long enough to take a voltage reading with your VOM as you proceed with the diagnosing & keep all lights/accessories/radios etc off even for that 5 seconds.

I got it fixed up. Was a bad main ground cable. Had 1.5ohms of resistance from battery lug to cable end on block. Never had a bad one of those before that wasn't obvious, or where car would still start fine.

The secondary body ground wire from the battery gave me good voltage at the fire wall, but the ignition box had a ground wire to the block, once I fixed that main ground and got full battery power to the ignition box and it quit dropping that whole circuit with the voltage regulator, everything started working as it was supposed to. Sometimes the ohm meter can be your best friend.

That's why MSD has us running both a red and a black wire to the battery.

What do you MSD users do to better the appearance of those wires?

R.