Voltage over 15 volts at all times. Stumped, see diagnostic list.

[pnora]

It is a simple system. If you have 16 volts going to your system, the voltage is not being properly regulated. The alternator will put out at least 17 volts if working properly and it is the regulators job to drop it down to 13.4 - 14 volts. It appears to me that everything is doing its job except the regulator.
That said, I would make sure the regulator case is grounded properly by testing with a digital ohm meter between neg post on the battery and the regulator case. Better be less than .02 ohms. With a good ground and still allowing more than 14 volts to the system, there is no other culprit to blame IMO.

Input voltage at the regulator is what controls it. Lets say 14.0 is target regulated voltage. If the input sees 13.8 it will step up the charge. If it sees 14.2 it will step down the charge. The plug on the regulator is a known culprit. Loss of voltage between the wire and regulator pin will cause an over charge condition.

 

[snakeoil24]

Continuity doesn't check the circuit for integrity under load. To do that you need to do a voltage drop test. Set the meter set to DC volts. One end directy to the negative battery post. The other end to the ground you wish to test. Such as the regultor itself (not the mounting bolt). Then watch the meter. it shouldn't go over .5 volt while the failure is occuring. The hot side can be checked the same way. Positive battery stud to the output stud at the alternator. I'm going to discount the alternator or regulator since you have substituted other parts. Either there is a grounding issue at the regulator case. A poor connection between the alternator output stud and the battery. The "F" circuit is rubbed thru to ground. The "I" circuit has voltage is fluctuating. I worked at the FCA electrical lab 9 years debugging prototype vehicle electrical issues. Saw plenty of poor crimps, heat shrink glue seeping into terminals, poor grounds that were tight and showed low resistance when measured with an ohm meter.
Doug

Dvw you know your stuff!!!

 

[dvw]

When I started at a dealership early in my carrer a leason was learned. It was a simple tail light inop. I checked for voltage which was normal. Checked resistance to ground normal. Swapped the bulb. It still didn't work. The guy next to me came and showed me you have to load the circuit to properly test. He had a headlamp bulb with jumper leads. He told me not to use a regular test lamp because it doesn't draw very much amperage. With the test unit connected to battery on one end and the ground side of the socket, it lit. Grounding the test unit and conncting to the power side of the socket resulted in no light. I traced it it back under the car. The factory harness had been cut and spliced for a trailer plug. Coroded and poor conection. At FCA we got into some really deep and wierd issues. Especially with proto types with mulyiple splices, wire color changes in the same circuit, Voltage inductance inducing voltage in circuits that ran along side, EFI. The list goes on. It was a challenging and fun job.
Doug

 

[pnora]

When I started at a dealership early in my carrer a leason was learned. It was a simple tail light inop. I checked for voltage which was normal. Checked resistance to ground normal. Swapped the bulb. It still didn't work. The guy next to me came and showed me you have to load the circuit to properly test. He had a headlamp bulb with jumper leads. He told me not to use a regular test lamp because it doesn't draw very much amperage. With the test unit connected to battery on one end and the ground side of the socket, it lit. Grounding the test unit and conncting to the power side of the socket resulted in no light. I traced it it back under the car. The factory harness had been cut and spliced for a trailer plug. Coroded and poor conection. At FCA we got into some really deep and wierd issues. Especially with proto types with mulyiple splices, wire color changes in the same circuit, Voltage inductance inducing voltage in circuits that ran along side, EFI. The list goes on. It was a challenging and fun job.
Doug

Yup. Erroneous voltage.

 

[4406bbl]

When I started at a dealership early in my carrer a leason was learned. It was a simple tail light inop. I checked for voltage which was normal. Checked resistance to ground normal. Swapped the bulb. It still didn't work. The guy next to me came and showed me you have to load the circuit to properly test. He had a headlamp bulb with jumper leads. He told me not to use a regular test lamp because it doesn't draw very much amperage. With the test unit connected to battery on one end and the ground side of the socket, it lit. Grounding the test unit and conncting to the power side of the socket resulted in no light. I traced it it back under the car. The factory harness had been cut and spliced for a trailer plug. Coroded and poor conection. At FCA we got into some really deep and wierd issues. Especially with proto types with mulyiple splices, wire color changes in the same circuit, Voltage inductance inducing voltage in circuits that ran along side, EFI. The list goes on. It was a challenging and fun job.
Doug

The headlamp bulb is the best load test there is in my opinion, I use a high/low beam on the computer controlled cars to test every circuit to 10 amps before sending a computer in for a "rebuild"....what a joke those companies are when there computer will not work right. I have a diesel computer right now that was sent in that will not hold enough current on the ground to hold the ASD relay, but will light a test light. They say it tests good, I asked if they load tested it...no response. It also overcharges and will not temperature compensateafter they worked on it, but a junkyard computer works perfect, they don't know why, but if I open the computer to look, no warranty, what a joke. Trust nothing.

 

[toolmanmike]

The headlamp bulb is the best load test there is in my opinion, I use a high/low beam on the computer controlled cars to test every circuit to 10 amps before sending a computer in for a "rebuild"....what a joke those companies are when there computer will not work right. I have a diesel computer right now that was sent in that will not hold enough current on the ground to hold the ASD relay, but will light a test light. They say it tests good, I asked if they load tested it...no response. It also overcharges and will not temperature compensateafter they worked on it, but a junkyard computer works perfect, they don't know why, but if I open the computer to look, no warranty, what a joke. Trust nothing.

I was on the tool truck when the "computer safe" LED test lights came out. Yep, a lot of mis-diagnosed circuits on regular 12v. circuits. Now, for that type of testing, a tech that knew how to run a Power Probe had the world by the tail. You had power and ground at the flip of a switch and it was circuit breaker protected.

 

[lewtot184]

when i've had excessive voltage it was always poor regulator grounding.

 

[toolmanmike]

when i've had excessive voltage it was always poor regulator grounding.

Been there, done that.

 

[AR67GTX]

So if not a highjack, what is considered the maximum safe voltage level? Both my 66 and 67 run 14.5 - 14.6 volts with rebuilt, round back, standard alternators and solid state regulators?

 

[hunt2elk]

So if not a highjack, what is considered the maximum safe voltage level? Both my 66 and 67 run 14.5 - 14.6 volts with rebuilt, round back, standard alternators and solid state regulators?

Was just thinking the same thing. I know none of my cars run in the 13.8 - 14.2 volts that they are supposed to. Mine are all like yours.

 

[dvw]

The regulator checks voltage on the "I" feed. It bases that voltage against it's own ground. If there is a discrepency in either circuit the regulator sees an incorrect voltage. It then send field current to the alternator based on that voltage. It's not rocket science. But it can be frustrating to find. A voltmeter doing a drop test while driving th ecar when the failure occurs will pin point which circuit. Then it's a connection to connection test at each spot in that circuit until you hit the failure point. Trust me I've chased stuff for weeks.
Doug

 

[4406bbl]

The chase is why I always put a harness on that eliminates the internal car wiring, then you can figure out if it is the regulator, alternator, or battery. I do ground the regulator to the battery during testing. Some new electronic regulators do not temperature compensate right anymore. See post #12 for the chart.

 

[72RoadrunnerGTX]

Okay I have been chasing this for 2 months.
It is a 72 Charger with 70 amp alternator square back 2 field
Fully replaced engine wiring harness when restored 10 years ago
Replaced the bulkhead connector last year
Replaced the ignition switch and fixed al the connections {did this today}
Checked continuity from field wires to regulator ok
Checked continuity from blue field to blue on ballast ok
Checked continuity between fields ok
Checked voltage reading between blue wire in ballast and battery in run it is high 1.3 volts both before and after changing ignition NOT OK
Have tried 2 different regulators 1 is new Mopar reproduction with modern guts other is 1972 known good regulator both have great grounds
Wires are tight on amp gauge
Have a bypass helper wire from alt output to battery connection at starter relay 10 gauge with a fusable link.
Firewall has ground strap to back of engine
Even tried a known good 40 amp alternator same result
Where else to look?

Not seeing any posts addressing the voltage drop noted in the original post. You have a 1.3 volt voltage drop between the reference voltage lead at the regulator (blue wire) and the battery while under load? That needs to be corrected, take voltage drop measurements at all the connections between the battery and blue wire at the VR, bulkhead connectors (12ga red), ignition switch Molex (red), ignition switch, ignition switch Molex (blue, ign 1), bulkhead connection (blue) engine harness. Isolate/correct any high resistance connections. Voltage drop should be as little as possible, now more than .5 volts total.

 

[72sunroof]

So I fixed the junction under the dash.
No change
Went into my trunk and pulled out a made in USA Niehoff voltage regulator
13.8 volts.
2 bad regulators including a 18 month old reproduction Mopar performance voltage regulator "with modern electronics"
They make garbage today.

 

[4406bbl]

So I fixed the junction under the dash.
No change
Went into my trunk and pulled out a made in USA Niehoff voltage regulator
13.8 volts.
2 bad regulators including a 18 month old reproduction Mopar performance voltage regulator "with modern electronics"
They make garbage today.
View attachment 1425825

Junk parts, you have that right. The computer repair shops are also getting the voltage a little too high lately. Out of spec components I would guess.

 

[4mulas]

I tried 4 different new regulators on one car until k found one that worked as it should

 

[Sixpactogo]

So I fixed the junction under the dash.
No change
Went into my trunk and pulled out a made in USA Niehoff voltage regulator
13.8 volts.
2 bad regulators including a 18 month old reproduction Mopar performance voltage regulator "with modern electronics"
They make garbage today.
View attachment 1425825

Glad you found one that fixed the problem. Just for shits and giggles though, I would relocate that star washer between the regulator and bulkhead so it bites into the paint. It may help down the road.

 

[Darter6]

They make garbage today.

Amen to that .

 

[mikerman]

Chased same problem for 2 years. Ate 4 batteries. Ruined 2 holidays.
There is a bad connection in the bulkhead connector. Finally fixed by the 4th mechanic who looked at it.
Mopars are notorious for over volting. And crappy grounding.

 

[72RoadrunnerGTX]

If you are referring to the undercurrent-rated Packard terminals in the charge circuit at the bulkhead connector, that’s a well-known Chrysler weakness that dates back to when these cars were relatively new. Plenty of other threads on that subject here.

As for “Mopars are notorious for over volting and crappy grounding”, disagree, Mopars are no worse than any other brands neglected/abused 50+ year old electrical wiring.