Generator overcharging?

[Joe Flanagan]

Well, I drove my car (really drove it) for the first time this morning and all I can say is it's incredible. It handles as smoothly as a new car, the steering is amazing. It's nice and quiet and the brakes are unbelievable. All I have to do is touch the pedal with my toe and the car responds. Installing discs in the front turned out to be a great idea. I had no idea what a difference it would make. I only drove it up and down the street a couple of times because I don't have the brake lights installed yet. But also I stopped driving it because I think the generator is overcharging. 

For a long time, the ammeter has been acting like a tachometer. It never settles down to the midpoint of the gauge no matter how long you run it or how long it's been on the charger. After driving it today, I could smell a strong electrical burning smell under the hood and I'm pretty sure that's coming from the generator. Both the generator and voltage regulator were so hot you couldn't touch them. The VR is new (or was a few years ago, but it's seen barely any use). The generator was rebuilt by a shop. Both were tested at the time and both were OK. I'm sure I have the wires hooked up right but will check once more tomorrow. I did polarize the generator, too. I was going to take the vr off the car tomorrow as well and see if the points on the circuit breaker haven't stuck together but I believe I checked that some time ago and they looked fine.

Anyway, just looking for some ideas and some things to check.

Thanks. 

[dlrides]

The service manual has a fairly simple test process for the generator and regulator. Once their operation have been checked, start looking for a short to ground. The ammeter bouncing around seems to indicate regulator.

I recently had the exact issue, and it was a grounding problem. Check all your grounding cables/wires.

Edited August 2, 2014 by dlrides

[Jim Yergin]

Joe,

Congratulations on the first drive. I take it you sorted out the problem with the leaking master cylinder. I know you will figure the charging issue. Great milestone.

Jim Yergin

[Joe Flanagan]

Yes Jim, I disassembled the master cylinder and replaced the rubber parts with spares I had on hand. The cup on the piston had a slightly rough edge to it so that might have been it. Thanks for coming by last weekend.

Concerning the ammeter, it's not jumping around so much as pegging hard to the right on acceleration.

[Plymouthy Adams]

follow the trouble shooting step in the book and do look close at the regulator adjustments and possible sticking contacts

[LAKOTA169]

I had a similar problem about 3 weeks ago. The amp needle was more than half way to the right (charging) while I was driving with my headlights on. Turned them off and it dropped to just right of the "0" mark (normal position when driving). I have a headlight relay installed on my '37 and normally the amp gauge isn't affected by the headlights being on. Checked the battery and the water level was good. Cleaned the battery posts and the connections on the starter switch. Cleaned the connections on the headlight switch, both generator terminals, and the terminals and contacts on the voltage regulator. Now, when the engine is running, the amp needle is on the left side of the "0" mark (-). Won't go to charge at all (but also doesn't move when headlights are on). Does move slightly left when brake lights are on. Voltage at battery is 6.19v (engine off) and 6.0v (fast idle). VR BATT terminal 6v. Generator terminals .4 & .5 (idle) and .8 both terminals at fast idle. Manual says battery should show 7.4v-7.8v when charging. I also tried repolarizing the generator. Thinking the generator (brushes?) may be bad. And to make matters worse, went to drive my '05 Magnum R/T Friday, and it won't go out of park. Read where there is a shift interlock latch that is plastic and breaks. Last week, my wife went to back out her 2000 Dakota R/T, and the brake pedal went to the floor. Seems a metal brake line has broke. Things are not looking too good for the Mopars at my house. The only thing running is the Subaru Outback.

[Niel Hoback]

  Ammeter acting like a tach sounds like the field is grounded eliminating the regulator. Don't race the engine or you will over heat the generator and melt the lead out of the commutator.

[Joe Flanagan]

Niel, would the field being grounded be a condition inside the generator, like maybe the field terminal being broken or making contact with something it's not supposed to?

Thanks for the responses, everyone else. I'll start going down the list today.

[Joe Flanagan]

Following one of the tests in my manual, I checked for a ground in the field coils (because this is a quick and easy test). I put a test probe on the field terminal and one on the generator frame and the light goes on, which it should not. This also happens when I test the armature terminal. Insulation on both studs damaged?

[greg g]

with the engine running and higheams on, operate the signals, what is the amp gauge doing?  Is the battery fully charged?  The simplest cause may be that the regulator is not properly grounded do to all your new paint.  Did you go through the service manual procedures for fault finding?

[Joe Flanagan]

I thought that grounding might be an issue some time ago so I grind the paint off the bosses on the firewall where the regulator mounts. I just discovered that the battery will not crank. It currently has 5.9 volts. I'm going to put it on the charger and go from there.

[Niel Hoback]

I believe the field should only be grounded through the regulator since that's how it controls output. With the field grounded, there is no control and no limit to the output. 

I'd check the insulation at the terminal where it goes through the housing to make sure its still there.

[Joe Flanagan]

Just out of curiosity, I removed the voltage regulator and took a look at it. The cutout relay appears to be discolored and possibly burned. The cutout relay is the one on the far left:

 

 

In addition to that, the contact is bent, as you can see in this picture. This is exactly how it came out of the vehicle:

 

 

Here's another picture of the discoloration on the cutout relay:

 

[Dodgeb4ya]

That doesn't look good. The lower contact is at a bad angle too!

[Niel Hoback]

  That can't be right!

[Joe Flanagan]

Yes, I would say it's probably not right. Since I posted those pictures, I removed the generator and disassembled it. The insulation for the armature terminal is discolored and partly melted. The shop used plastic insulators for both studs. Also, with the case separated from the generator, I no longer get continuity between the terminals and the case itself. So at this point I'm thinking maybe it's not a problem with the insulation around the terminals. Why I got continuity with the unit assembled and in the car, I don't know. 

[Jim Yergin]

Joe,

When you had continuity at the terminals when it was in the car, were the terminals still connected to the regulator?

Jim Yergin

[Niel Hoback]

That would explain it.

[Joe Flanagan]

No, I had them disconnected at the regulator with both wires just hanging from the generator. I checked to see if there has been any contact between the inside of the case and the rotating part of the generator and there is no sign of any. The bushings at both ends are new, too. 

[Joe Flanagan]

Today I reassembled the generator and put it back in the car. I also repaired the bent contact on the voltage regulator and set the points to the recommended .015 called for in the manual. I checked the specific gravity of my battery and if my hydrometer is correct, all three cells need recharging. And that is after well over 24 hours on the charger. So my battery is apparently bad. It cranks fine and shows 6.18 volts right after I've taken it off the charger. Anyway, I put the battery and voltage regulator back in the car and tried again, just to see if fixing the bad contact in the vr would make a difference. The condition still exists with the ammeter pegging hard to the right when you accelerate. Is it because I have a bad battery?

I'm not sure, because I think this condition existed back when I had another battery (which eventually went bad). Is this condition, whatever it is, killing batteries? And just to clarify, you can let the engine run for an hour and it will still peg hard to the right on acceleration. I don't believe this is just the battery getting recharged after starting. I once set the throttle at high idle and let it run to see how long the ammeter would read 40 amps and it stayed at 40 for so long I shut the car off because I was afraid I was going to fry something. 

Concerning the grounding issue, this time I ran a ground wire from one of the voltage regulator mounting screws to a bolt that goes through the inner fender, so I think I have that covered. It seems to make sense that if the voltage regulator cannot regulate what the generator is doing, then the generator will produce large amounts of voltage, which sounds like what is happening. In any event, it looks like I need a new battery (unless you guys think another 24 hours on the charger is going to make a difference) and I also have a new regulator on order. 

Edited August 4, 2014 by Joe Flanagan

[Merle Coggins]

It sure sounds like your generator is at full output all of the time. And yes, that can cook and damage a battery.

Could you have some wires crossed causing this problem?

Didn't you say this was a new regulator? How did the points get damaged?

Could it be a 12 volt regulator and is keeping the generator at full output trying to get the voltage up to 12+?

Have you measured the voltage output during this full charge condition?

[Joe Flanagan]

Merle,

I checked the wires and they are correct. It's a "new" regulator, meaning a few years old with very little use. Some time ago, while trying to discover what was causing this problem, I removed it and checked the points. I must have done something while reinstalling it or otherwise fooling around with it to bend that contact because I can't imagine how it would happen otherwise. It is a 6-volt regulator. Says 6v on the unit itself. I have not measured the voltage output during the full charge condition. Would that be done with the engine at high idle and the ammeter reading 40 amps?

[Don Coatney]

I suggest you bur a new battery as apparently your battery will not hold a charge. That will fix one of your problems but I believe you still have issues.

[Merle Coggins]

Yes, measure the voltage when your ammeter is reading high amperage.

Also, one test you could perform easy enough is to disconnect the Field wire at the regulator and see if the generator output drops to zero. If it does that should point to a faulty regulator. If it doesn't that would point to a generator issue, or a grounding wire issue.

 

Merle

[Niel Hoback]

I wouldn't change the battery until you put on a new regulator.  You have proven the generator is working.  If the regulator was working right, it would limit the charge to 35 amps, no matter what the battery condition is.