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Ask Dodgerench Your Own Question
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3404
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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I put a 60 amp alternator..electronic..voltage regulator

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i put a 60 amp alternator on my 1969 roadrunner. i know the
alternator is good. i have replaced the electronic voltage
regulator. i appears to have heavy enough wires to carry the
added voltage. it will not put out more than 30 amps!
Hi and welcome to Just Answer!.

Although it's pretty rare, you might not have sufficient grounding on the alternator case, especially if the engine is nicely detailed and painted. Start it up, put a load on the alternator (lights, heater blower) and check for residual voltage on the alternator case itself. You can do this with a voltmeter or even a test light connected to battery negative.

Any voltage shown on the meter denotes some loss of grounding, but a few tenths won't cause what you're looking at. Expect 6 or more volts in that case.

Check it out and we'll push on from there if needed.

Talk shortly,
Dodgerench and 7 other Dodge Specialists are ready to help you
Customer: replied 7 years ago.

i tried that. at idle alternator charging at 12.65 volts no load on alt.

voltage from alt frame to car frame .03 volts


at idle with brites and a/c alt charging at 11.71 volts and still

.03 volts from alt frame to car frame.


ps i tried that because you told me to.


what else do you think?

Customer: replied 7 years ago.

i tried that. at idle alternator charging at 12.65 volts no load on alt.

voltage from alt frame to car frame .03 volts


at idle with brites and a/c alt charging at 11.71 volts and still

.03 volts from alt frame to car frame.


ps i tried that because you told me to.


what else do you think?


forgot to add, at fast idle with load

alt charging at 12.20 volts still .03volts

from alt frame to car frame

Thanks. One of your posts appears to have gotten lost in space.. sorry if it appears I've been ignoring you... =/

With good case grounding, we move on to the regulation portion. Does your alternator use one or two plug-in terminals at the rear of the unit?

Was the output voltage you measured at the battery or at the output stud at the rear of the alternator? If you haven't checked yet, test it right at the output stud.

Customer: replied 7 years ago.

1. 2 field slip on connectors and one output post

2.the output voltage was at the battery. meter on + and - terminals


i'll test it at the out put stud in a few minutes and let you know what we


That would be great. While there will always be some voltage drop over a length of cable that DC current flows through, you shouldn't see more than a tenth of a volt or so if the cable is sized to handle this output.

If output is low, check your power supply to field control with the engine running to see if it's dropped in voltage from what you would get directly at the battery. If low, feel free to jumper straight 12v to this terminal while monitoring alternator output.

Then check voltage with the engine running at the regulator terminal. If the regulator is asking for maximum output, all voltage will be sucked off of the circuit. It will be a ground circuit only.

Residual voltage means either the regulator isn't able to ground the circuit completely or your control circuit to the regulator has some resistance on it. Feel free to jumper a ground to this circuit at any time as a test for maximum output. The electronic regulator's case is the final path to ground for this circuit, so make sure the bolts holding it to the body have good tightness and bite on the unit. You might have to buff the paint off on the mating surface on your Charger to get the contact needed from your new regulator.

And last (for now), feel the alternator pulley after it's been running for a bit. If there's any slippage present, it will be QUITE hot, so be careful.

Customer: replied 7 years ago.

last nite i attached a wire straight from the battery(while the car was running)

and attached it to both field terminals. as i understand it, this should have maxed

out the alt. all i got was 11.92 volts.


what else could it be other than something weird going on in the alternator?

unless you got something else, i think i'll change it out. i think that you have

earned the money, but if you can think of anything else, i'm all ears.



It doesn't actually work that way.
Field control is fed in one direction and grounded in the other. I'm a little fuzzy on the direction things run on the 69 models because it was pretty close to the time when your voltage regulator actually output the voltage to the alternator... which had a permanently grounded second brush.

Since you have two brushes, let's find the hot one first. Pull one terminal off, then turn the key on. Measure this wire and then the one left on the alternator. Only one should be hot.
The other wire is likely the one that goes to your regulator and is probably green in color.

The alternator itself might have a bad diode, which will reduce its output by about 1/3. It's hard to test on the car (or bench) but makes a distinctive waveform on an oscilloscope if you have one handy (doesn't everyone?).

Recheck your wire polarities first and we'll do a test or two before you head back to the store, where they will probably have a bench tester to check total output, which as a last resort will tell the story.

I've got an appointment about 45 minutes from now in case you can't find me.

Talk shortly,
Customer: replied 7 years ago.

thanks, i'll try that at lunch and let you know. i sure appreciate the help.


You bet. See ya in a bit!
Customer: replied 7 years ago.

one of the mechanics i work with found a bad conncection in the firewall wir bundle.

it would not start. he bypassed the wire and now is charging at 13+ amps.

i am satisfied with your help. thanks again.



Things went from bad to worse, huh?

Many thanks!