70 SS. It seems like I cant keep VRegulators in this thing, I have flickering lights off of a new 100amp Alternator. I have an external VR and mesure 14-17 volts at 2000 rpm at the battery. Have verified the ground straps and seem to have good connections all around including ggod grounds at engine, body, chassis etc.

Did notice that the wires from Alternator change color on their way to the VR. So to start, which terminal on the 2 prong connector at the alternator is #1/#2? From the front of the car with the connector clip lock to the front is #1 on the R or L? Because when I swap F and 1 at the VR, the flickering stops but voltage at battery is solid 12.8 v @2000rpm.

This is the second VR replacement. I also lost an MSD box cuz of this I think.

Thanks!!!!!!!!

Some other info:

I looked at Paul F explanation and I do infact have voltages as described in his article
f=4 slight V (2.9vdc) KoEo
2 = 0v
3= 12v

So now what?

70 SS. It seems like I cant keep VRegulators in this thing, I have flickering lights off of a new 100amp Alternator. I have an external VR and measure 14-17 volts at 2000 rpm at the battery.
Are you sure it is a externally regulated alternator? If you can't tell the difference see my post here (http://www.chevelles.com/forums/showthread.php?t=105661)
14-17 is quite a swing in voltage a 2k rpm.

Did notice that the wires from Alternator change color on their way to the VR. So to start, which terminal on the 2 prong connector at the alternator is #1/#2? From the front of the car with the connector clip lock to the front is #1 on the R or L?
See the post above,

Because when I swap F and 1 at the VR, the flickering stops but voltage at battery is solid 12.8 v @2000rpm.
Do you mean "F" and 2? When swapped it won't charge at all.


Some other info:

I looked at Paul F explanation and I do infact have voltages as described in his article
f=4 slight V (2.9vdc) KoEo
2 = 0v
3= 12v

So now what?
Personally, if you want to run a high amp alternator, convert to a internally regulated one. Could also be that the VR's that you are using are not compatible with a high amp alt. Is this the explanation that you seen?

This was written by another member, a very good write up on how it works and how to troubleshoot a externally regulated charging system.

I dug this out from before, hopefully it help. If not, just post or send me your questions.

I'll try to provide a simplified explanation of how the externally regulated alternator and regulator work here. This explanation starts from a parked car with engine off state.

The regulator brown #4 wire is connected through the light bulb to 12V whenever the key is in the ON position. The other end goes through a set of points in the regulator and then out the F terminal to the field winding in the alternator. So some current begins flowing in the field winding from this connection. The little bit of current flowing produces a weak magnet field in the alternator and also lights the bulb.

When you then start the car, the weak magnetic field from above begins rotating which makes the alternator producing a little bit of voltage. This voltage is fed from the alternator to the regulator on the white regulator #2 wire. This wire connects to a coil in the regulator and turns on a contact when the voltage goes above 3.2V.

Once the contact turns on in the regulator the #3 and #4 terminals are connected together. Terminal #3 is battery power so this puts battery power on both sides of the bulb and turns it off. This means the brown #4 wire should go to +12V. Also, this connects the field terminal right to battery power but still going through the points.

When the battery voltage goes above a set level, the F terminal is disconnected from the battery power by the points I kept mentioning. Then the voltage drops and the points close again. This on-off cycling happens rapidly and is how the voltage gets regulated.

From the above (KOEO = key on engine off and KOER = key on engine running).
F or #1 terminal (field) - KOEO = #4 slight voltage, KOER = 9-12V typically
#2 terminal (sense) - KOEO = 0V, KOER = >3.2V
#3 terminal (Battery) - KOEO = 12V, KOER = 12V
#4 terminal (light) - KOEO = F slight voltage, KOER = 12V

By 12V above I mean battery voltage, which may be 12V when engine is off but could be up to 14.5V when engine is running.

Check the light: Ground the brown #4 terminal wire at the regulator. When grounded the light should come on. If you don't have a light then skip this test. Test this with the connector off the regulator.

Checking the alternator: Jumper the blue wire F terminal to the battery post on the back. This should make it easily crank out 16+ volts. Next, connect a troublelight between the battery post and the F terminal. The light should come on and you should measure > 3.2V at the other alternator terminal. If it passes these tests, then it's in the regulator or wiring.

Checking the wiring: At the regulator connector jumper the brown light wire (#4) to the F terminal (#1) and you should be able to measure >3.2 volts on the other alternator terminal or terminal #2 of the regulator connector. If these tests pass, it is in your regulator.

When doing these tests, make sure you turn off or pull the fuses for any added electronics that you can. The alternator test can produce enough voltage to damage stuff.

Peter

Most voltage regulators available from the typical parts store are for alternators with less than 63 amps output. I would also think that a 100 amp alternator would require a compatible regulator. I'd venture a guess you have a high output alternator coupled with a low output voltage regulator. Do you have a spare low amp alternator available? Try swapping that in and see how if your problems go away. My guess is you are burning up VRs because your alternator is too powerful.

Do you have AC, a high power stereo, high power headlights and electric fans? You may not need all those amps. Bigger is not always better.

Thanks for the help but I am not there yet. Ok I have re-verified my setup and I am running an 80 AMP ALT not 100 as originally stated. I also have an AMPMETER in the dash that seems to work.