voltage regulator over charging battery

[440charger68]

I have a 1970 dodge challenger an the voltage runs at about 18 volts which i know is not good haha. The voltage regulator is brand new an has a good ground, but it is not regulating anything i have pulled the connection on the regulator when the car was running an it still was running the same voltage. So i have no idea of what it could be maybe its my alt i have no clue. Thanks Kyle

[Plumcrazy]

The green wire between the alternator and regulator may be shorted to ground or the problem is in the alternator.

Unplug the green field wire from the alternator and check the voltage again.

[68neverlate]

I have a 1970 dodge challenger an the voltage runs at about 18 volts which i know is not good haha. The voltage regulator is brand new an has a good ground, but it is not regulating anything i have pulled the connection on the regulator when the car was running an it still was running the same voltage. So i have no idea of what it could be maybe its my alt i have no clue. Thanks Kyle

Could be a few things... answers to these should help narrow it down:

1)  Stock alternator and regulator (ie: two field alternator and electronic two pronged "triangle plug" regulator)?
2)  Stock wiring?
3)  How old is the alternator?
4)  With engine off, disconnect the green and blue field wires from the field terminals at the alternator.  With a voltmeter, perform a separate continuity check on each field terminal on the alternator to ground.  Neither should give you a continuity reading.     

I suspect your alternator may have a short to ground which would take the voltage regulator out of the equation in terms of controlling voltage output on the alternator.  The result would be an alternator making max power all the time. 

I would recommend not running your car until you get this fixed... you can easily turn your engine and/or passenger compartments into blast furnaces.        Factory wiring was not designed to carry that kind of output for sustained periods...   

[440charger68]

Yeah it sounds like its the ground to the alternator, i'm gonna give it a try. I have another question the alternator on my 70 is a single field, is it suppose to be dual field? I really appreciate all the help Thanks Kyle.

[Plumcrazy]

Yeah it sounds like its the ground to the alternator, i'm gonna give it a try. I have another question the alternator on my 70 is a single field, is it suppose to be dual field? I really appreciate all the help Thanks Kyle.

That changes everything.  That's the wrong alternator

[myk]

How the heck did a single field wind up on a '70? 

[Finn]

My 70 challenger has the same problem with all new wiring and a new alternator.

[68neverlate]

Yeah it sounds like its the ground to the alternator, i'm gonna give it a try. I have another question the alternator on my 70 is a single field, is it suppose to be dual field? I really appreciate all the help Thanks Kyle.

Yup, absolutely... it should be a dual field alternator.  Single fields have the other end of the field terminal automatically going to ground, so it will do exactly what you're seeing, give you unregulated, maximum power.

Time to make a trip to the parts store...    

[Plumcrazy]

You need what's called an isolated field alternator.

[68charger440]

Yeah it sounds like its the ground to the alternator, i'm gonna give it a try. I have another question the alternator on my 70 is a single field, is it suppose to be dual field? I really appreciate all the help Thanks Kyle.

Did you get this figured out?  I have the same problem on my 68, only I had also upgraded my charging system to a 70 style dual field alternator and regulator setup.  I'm still looking for answers.

[440charger68]

Yeah it sounds like its the ground to the alternator, i'm gonna give it a try. I have another question the alternator on my 70 is a single field, is it suppose to be dual field? I really appreciate all the help Thanks Kyle.

Did you get this figured out?  I have the same problem on my 68, only I had also upgraded my charging system to a 70 style dual field alternator and regulator setup.  I'm still looking for answers.

I have a 68 also switched it to dual field, my old one was 50 amp i believe and the dual field i bought was 60 or 70amp but anyways i had to ground the prong for the other field on the alternator for it to work. Also went through two voltage regulators until i found one that worked. Havent had a problem since 

[68charger440]

Yeah it sounds like its the ground to the alternator, i'm gonna give it a try. I have another question the alternator on my 70 is a single field, is it suppose to be dual field? I really appreciate all the help Thanks Kyle.

Did you get this figured out?  I have the same problem on my 68, only I had also upgraded my charging system to a 70 style dual field alternator and regulator setup.  I'm still looking for answers.

I have a 68 also switched it to dual field, my old one was 50 amp i believe and the dual field i bought was 60 or 70amp but anyways i had to ground the prong for the other field on the alternator for it to work. Also went through two voltage regulators until i found one that worked. Havent had a problem since 

Thanks... Did you also change the regulator to the 70's style transistor type or did you stick with the original 68 points type of regulator?

[440charger68]

i got my regulator from autozone, and its the same regulator thats in my 70 challenger so im not really sure 

[Nacho-RT74]

on "dual field/pronged" alts, both brushes are isolated... this is because these will get constant positive from Ign Key ( blue wire ), and regulated ground or negative from regulator ( green wire ) hence the reason why both needs to be isolated.

on earliers setups with one prong alts, the constant source is negative, thats why one of the brushes is grounded to chassis. The existant prong gets regulated positive from regulator through the green wire

in both cases the regulated source goes through the green wire, earlies positive with mech regs, lates negative with elect regs