The Over Charger

[BigBlackDodge]

Grrrrrrrrrrrrrrr..............

Been chasing this grelim for a few weeks now.

My old alternator was starting to make some noise.........bearing was going out. So I got a new unit and dropped it in there (keep in mind that the system was working fine other than the noisey alt). Started the car after the install and everything was fine......until the next day when I started it up! Over charging! Pegging the neddle if given a little gas.

New Voltage Regulator you say? Yep, thats what I thought too. Got a new one in there, still over charges! Alright........maybe I got a bad one, got another.....still over charging! I have a nice collection of them now.

I still have my old alt so I bolted it back in................it's now over charging! 

So now I'm puzzled. Started checking wires and such finding nothing burnt, loose..etc.

Any ideas? Could the ammeter be faulty?

I'm at a loss here.


BBD

[70charger_boy]

remove the radio and hook up an ohmmeter to the back of the ammeter connections.  My guess is that its a bad ammeter or could be your battery connections are corroded

[Plumcrazy]

What happens if you disconnect the voltage regulator?

[BigBlackDodge]

What happens if you disconnect the voltage regulator?

The neddle still pegs to the right I believe..........plugged in or not. I've bought 3 new VR's thinking they were the culprit, but now I'm not so sure.

I'll be checking the ammeter today (I have a old one to experiment with)

BBD

[BigBlackDodge]

Update:


Disconnected the ammeter and wired it up twith he spare I had...........still pegs.

Swaped out the new alt with the old one with the spare meter still hooked up.......................WORKS!!!!!

Hooked the old meter back in line with the old Alt..........pegs the needle.

So...........

New Alt + old meter = pegs the needle
Old Alt + old meter = pegs the needle
New Alt + spare meter = pegs the needle
Old Alt + spare meter = Works fine.......things are regulated. \

So it seems the existing ammeter is not working properly with either alternator.

What could be wrong with the new alternator that would peg the needle on the spare meter but the old one does not?

Looks like I need a new meter (or swap it out with the one I have already) and maybe get the new alt checked out.


BBD

[70charger_boy]

was the alternator rebuilt to stock specs or is it beefed up?

[Plumcrazy]

What happens if you disconnect the voltage regulator?

The needle still pegs to the right I believe..........plugged in or not. I've bought 3 new VR's thinking they were the culprit, but now I'm not so sure.

I'll be checking the ammeter today (I have a old one to experiment with)

BBD

With the voltage regulator unplugged the alternator should not charge at all.  Are you sure the green wire between the alternator and the regulator is not shorted to ground somewhere?

[BigBlackDodge]

What happens if you disconnect the voltage regulator?

The needle still pegs to the right I believe..........plugged in or not. I've bought 3 new VR's thinking they were the culprit, but now I'm not so sure.

I'll be checking the ammeter today (I have a old one to experiment with)

BBD

With the voltage regulator unplugged the alternator should not charge at all.  Are you sure the green wire between the alternator and the regulator is not shorted to ground somewhere?

Very sure. I even replaced this wire today trying to get things figured out.

It's a over the counter stock alternator.


BBD

[Plumcrazy]

What happens if you disconnect the voltage regulator?

The needle still pegs to the right I believe..........plugged in or not. I've bought 3 new VR's thinking they were the culprit, but now I'm not so sure.

I'll be checking the ammeter today (I have a old one to experiment with)

BBD

With the voltage regulator unplugged the alternator should not charge at all.  Are you sure the green wire between the alternator and the regulator is not shorted to ground somewhere?

Very sure. I even replaced this wire today trying to get things figured out.

It's a over the counter stock alternator.


BBD

Run the engine at a fast idle and measure the voltage at the battery terminals with and without the voltage regulator plugged in.  I'm curious what they will be.

[BigBlackDodge]

What happens if you disconnect the voltage regulator?

The needle still pegs to the right I believe..........plugged in or not. I've bought 3 new VR's thinking they were the culprit, but now I'm not so sure.

I'll be checking the ammeter today (I have a old one to experiment with)

BBD

With the voltage regulator unplugged the alternator should not charge at all.  Are you sure the green wire between the alternator and the regulator is not shorted to ground somewhere?

Very sure. I even replaced this wire today trying to get things figured out.

It's a over the counter stock alternator.


BBD

Run the engine at a fast idle and measure the voltage at the battery terminals with and without the voltage regulator plugged in.  I'm curious what they will be.

With it plugged in I'm getting around 14.3 or so.........thats reving up pretty good.

Without it plugged in it was at 12.9 or so. The numbers were slowing coming down.

So it seems that the VR is working.........but the needle was still swinging the far right.

This is with the old alt. I did not have time to hook the new alt back for the readings at the battery.


BBD

[Plumcrazy]

Those voltage reading look normal.   If the ammeter is pegging it sounds like the ammeters shunt is bad.   Only a small percentage of the power goes through the ammeter,most of it goes through the shunt (bypass).   If the shunt goes bad  it forces all the power through the gauge which is not calibrated for it.   Thats why the gauge over reacts.

Check the brushes on the new alternator to see if they are properly insulated from the case.

[Chryco Psycho]

the alt could ahve a bad diode