Overcharging

[Ratroaster]

Guys, I need help again. I've got a 63 Belvedere with a new 50 amp single field alternator with a new
solid state VR. I'm charging about 15.4 amps. Ouch. I replaced the VR once and that had no effect.
Also I need to add that I've got an electronic ignition. I have heard tell that a single wire alternator
has to have a points style VR. Can anyone verify whether that is true. Additionally, any other suggestions on a solution would be appreciated. I have verified that the VR is grounded adequately
and the engine wiring harness is a new repo harness. So I'm running low on ideas.

Thank you.

Ken

 

[Mopars & Missiles]

....I have heard tell that a single wire alternator
has to have a points style VR. Can anyone verify whether that is true.

By "single wire alternator", I'm going to assume that you mean a "single terminal field coil" or "internally grounded field coil". My opinion is that what you have heard is FALSE. An electronic voltage regulator should work just fine.

To your problem, yes, 15.4 volts is about 1 volt or so too high. A voltage regulator needs to know two things before it can control the alternator properly. #1 is it needs a good vehicle ground, 0.0 volts or as close to the actual voltage at the battery NEGATIVE terminal as possible (which should be 0.0 volts). This ground reference is achieved through the case of the regulator mounted to the vehicle chassis. You already know this and have stated that you have a good ground. (Always verify with a DVM).

#2 is it needs to know what the battery VOLTAGE level is. This is provided by the wire that is labeled "IGN" on the voltage regulator. Here is where I believe you will find the problem. If this input is a volt or so LOW to the regulator, the regulator will tell the alternator to overcharge to compensate for what it thinks is a low battery. Again, this wire should have a voltage on it almost identical to the voltage seen at the battery POSITIVE terminal. Verify this with a DVM.

If the voltage at the IGN wire input on the regulator is LOWER than the battery positive terminal, you have some loss or VOLTAGE DROP across components in the cars wiring. Usually this loss is due to corrosion or a poor connection thru the firewall "bulkhead" connector or within the IGNITION SWITCH itself. So once you find and eliminate this "voltage drop" you will most likely have solved your overcharge problem.

Good luck!

 

[rcb]

What he said. Also, are you talking about a Gm style 1 wire? If so they are internally regulated and self exciting. They can have charging issues if that's what you've got now. So you would disconnect your regulator all together. I have several older tractors that we still use to do work. Some convert to those 1 wire alternators.

More to your question though, a couple minutes with your ohmmeter and you can verify if it's seeing a voltage drop. Is the voltage regulator of Chinese manufacture? If so it may need some work. It's not uncommon for those to need some alteration to properly control the field.

For my money though I'd check for a voltage drop/resistance in the line. On tractors the generators can run up to 16-17 volts and cook a battery if the regulator isn't adjusted properly, generator adjusted or bad connection.

 

[Ratroaster]

Update. First, a clarification on the alternator in question. It is a '63 vintage Mopar round back with a output post & 1 field wire. (green in a stock harness ).
Second, and more disconcerting is that I took the alternator to be tested and they could only get 11.5 volts out of it. The guy
who tested it is pretty experienced on testing these older alternators. So between the test ( 11.5v ) and what I'm reading on both a
DVM and an aftermarket voltmeter in the car ( 15.4v ) I'm now totally confused. I'm going to reinstall this alternator & double check everything, but if history is any indicator, it'll be reading over 15v again and I'll be pulling out my hair.

 

[rcb]

Where are you measuring voltage right now? At the battery? Have you tried at the alternator and regulator? With the ignition on (but not running), read voltage at the battery. Then read it at the "bat" terminal on the regulator. They should be basically the same.

I'm not intimately familiar with a 63, but are both crank pulleys the same diameter (they usually are)? Also, is the pulley on your alternator the original or did it come on the new alternator? I know it sounds funny, but I would compare the new alternator pulley to the old one (if the pulley is new). If the new pulley is smaller, that could be enough to cause your issue.

Ultimately, I suspect the regulator. Even if it is new. But those are a couple other things I would check before sending it back.

 

[1968rick]

The update to electronic ignition suggested a 2 field wire alternator...circa 1970....If you use an earlier alternator you can buy an electronic VR off E-Bay.
The reason for the Electronic VR is to give the ignition a constant voltage. ever notice when you turn on the lights the amp meter flucuates?
I just converted my 68 alternator to Electronic control and no problems at all. The older EVR controls the + current to the alternator. The newer 2 wire alternator control the - current from the alternator.
Hope this is understandable....

 

[Rick62]

I've been hunting for the source of the same problem on my '62. I have been able to determine that the problem is a voltage drop between the battery and the voltage regulator. The voltage at the ignition terminal on the regulator is almost 2 volts lower than the battery. This causes the overcharge. By measuring voltage at the blue wire coming out of the bulkhead connector it appears the drop is occurring under the dash. The usual suspects are the soldered connector under the dash where several feed wires are soldered together at the factory and the ignition switch. I have a new ignition switch that I plan to install in the next week or so. I'll let you know how it goes.

 

[Ratroaster]

Update #2. Today I did a test on the voltage between in the battery & the IGN side of the VR with the key in the run position.
Voltage difference was .15 volt. However, when I intially did the test the electric fuel pump was on and there was a drop
of about 1 volt. Don't know if the fuel pump is significant or not. Tomorrow I'll fire it up and see where I stand.
Thank you all for your input to date. I'll keep beating on it.

Ken

 

[ckessel]

I thought overcharging only applied to taxes.

 

[rcb]

Did you compare the new alt pulley to the old one (or did you just reuse your old one?) I'm saying your voltage regulator isn't working correctly.

Turn your headlights on while it's running. Measure voltage. Try putting in a analog regulator and see what it runs. To be honest, all I do on my old tractors is clean them. You can also adjust the old voltage regulators (well AC Delco ones at any rate). Anyhow, put an old one on and run it. See what the charging condition is like.

 

[wvmarv]

Aren't those VR of that type adjustable? My memory isn't as good as it once was, but I think you can take the cover off of that type and adjust the output. It should be putting out between 13.8 and 14.2 volts at idle depending on the battery state of charge.

 

[rcb]

He said he had bought a digital vr. Most of those are not adjustable without digging the pot out. The old type is certainly adjustable.

 

[Bruce]

My brother had the same problem with his 64 Sport Fury after changing the regulator twice we sanded the back of the regulator mounting holes and used star washers and also cleaned paint off firewall by mounting holes worked great after that.

 

[Ratroaster]

Update #3. Well, I'm still chasing this problem around with no solution in sight. I now have about a .75 voltage drop when
checking the voltage difference between the battery and the ING side of the VR. Don't know if that's enough of a difference to cause serious overcharging. Voltage reading is the same at the battery and output stud of alternator. I guess I'll take the
alternator to an actual alternator shop and verify it's condition before spending $$$$ elsewhere.
Any suggestions on isolating location of a voltage drop if it's under dash???

Thanks again.
Ken

 

[Mopars & Missiles]

Ken,

It's kind of coincidental, but I am working this same exact problem on one of my cars right now. What I've been doing is checking the voltage at the bulkhead connector to narrow down the possibilities. You have to disconnect the engine wiring harness and use a couple jumper wires with 1/4" spade lugs to plug back into the bulkhead to do this. Since you have a '63 and mine is a '69, I'm not familiar with the wiring on your car and it probably isn't quite the same as mine.

Anyway, since the fusible link (+12V supply to inside of car) is on the connector that I have to disconnect, I use a jumper there to put power back into the inside of the car. Then I use another jumper to connect my DVM to the pin that power comes back out of the car on and goes to the voltage regulator (this is the wire that goes through the ignition switch contacts). When I do this I see a slightly lower voltage, but it is also pulsing so it is hard to get a good reading on the DVM since it is constantly changing. I believe this pulsing is being caused by the voltage limiter on the dash gauges, I don't believe this is a good thing and need to check this out further.

Also with the engine harness connector off, you can check the wire from the bulkhead connector directly to the voltage regulator connector to see if there is any excess resistance in that wire. It should be ZERO ohms on that short of a wire. Also I took all the wires out of the plastic connector housings one wire at a time and cleaned them thoroughly with a wire brush and then soldered the connectors to the wire at the crimp, even though this engine harness is nearly new. As a result, I am confident that the voltage drop problem is NOT in the engine harness but rather inside the car. Likely the contacts in the ignition switch are causing the problem, but there are a couple other connections under the dash that I have to check as well.

So, just to make your trouble shooting easier, use the "divide and conquer" method like I'm doing to eliminate small portions of the circuit one section at a time. Eventually you will isolate the culprit. Good luck!

 

[Ratroaster]

M & M, Thank you for the helpful input. I'm sure our harnesses are a little different but I like the plan. I'm working with a
brand new repo engine harness and ebay sourced dash harness ( the car was wired with a E-Z Wire fuse box and a rats
nest of owner installed wires ). So I hunted up the replacement dash harness. I've been using a copper infused anti-sieze on all the connections in an attempt to make sure all the connections are good. I'm hoping my problem's going to be something simple like the ignition switch. '63 dash harnesses appear to be unobtanium. Thanks again.

 

[Rick62]

Update #3. Well, I'm still chasing this problem around with no solution in sight. I now have about a .75 voltage drop when
checking the voltage difference between the battery and the ING side of the VR. Don't know if that's enough of a difference to cause serious overcharging. Voltage reading is the same at the battery and output stud of alternator. I guess I'll take the
alternator to an actual alternator shop and verify it's condition before spending $$$$ elsewhere.
Any suggestions on isolating location of a voltage drop if it's under dash???

Thanks again.
Ken

I'm not positive about this but, at least in my case the overcharging amount, measured in volts, is about the same as the voltage drop. Maybe one of the electrical guys will reply and confirm this.

 

[rcb]

Well, that would get you down to 14.65 volts, if you resolve that voltage drop. Usually you want to see around 14 volts +- .5 volts. So you'd be really close.

I'd go down to autozone. The VR for a 63 is $30. Swap it in and run it. If it doesn't change anything, take it back. Actually, most VRs you buy now are digital, they just don't say it as they are cheaper/faster to make than the old analog types.

Out of curiosity, when you checked ground, did you check it back to the battery or the frame?

 

[Mopars & Missiles]

FYI, Update on what I've found so far.

Since I have a second '69 (charging system works perfectly) identical to the problem car, I checked the voltage it is seeing at the regulator to compare to the problem car. The second car's voltage at the regulator is within 0.1 V of the voltage measured at the battery terminals. Also, there is NO PULSING of the voltage like that of the problem car, it is rock steady.

This is what I would have expected to see and now I have to find out what is causing the problem on the other car.


Also as for the voltage overcharge amount, I don't think it will be a linear amount, but probably more of a proportional relationship. In other words, 1 volt of drop at the regulator is not equal to 1 volt of overcharge from the alternator. Although the voltage regulator compares "battery voltage", it outputs "current" to the field winding of the alternator to control the alternator output.

In Ratroaster's case of having 0.75 V drop at the regulator, I suspect this would equate to more like a couple volts of overcharge but that is only speculation at this point as I have no data to support this theory at this time.

 

[Ratroaster]

Update #4 I took the alternator to a reputable alternator shop ( 40 miles one way )and it tested good. I've checked the ground from the battery ground cable to the VR housing and appears good. Although I'm going to add a ground from the
block straight to the VR. I guess I could try one another new VR and see what happens. Also considering a ignition
switch replacement as I have no idea of the age of one in the car. Assuming all this comes to naught, I'm going have to
obtain some expertise in chasing voltage drops. Mopars & Missles gave me a good start. I really dislike auto electric.
Thanks again for all the help.