Charging problem - Part II

[AR67GTX]

Well - I thought my charging problem was resolved. I made a couple short drives with good voltage and the alternator charging fine. We set out yesterday afternoon for our monthly cruise in about 15 miles away. About 2/3 rds of the way there I looked down and saw about 11 volts and noticed the amp gage was discharging again. I shut off the air (wife not thrilled now) and continue on since I'm most of the way there. We end up overstaying because of the huge crowd and I ended up driving home in the twilight and dark with someone tailing me. I made it OK running about 11 volts and constant discharge and lights burning - but not too brightly. My tail said my taillights seemed to stay about the same all the way.

I checked the battery voltage at home and got 12.6 volts and went to bed. Worked on it this morning. Cleaned all the bulkhead connectors and greased them with dielectric grease. Also cleaned the horn relay contacts for good measure. Started the engine and it's showing about 12.4-5 volts at the battery with no load - doesn't change when I increase engine speed. I pulled the wire off of the alternator field terminal and grounded it to frame - still about 12.4 volts. Then I tested the voltage between the hot lead on the alternator and the battery - still about 12.4 volts.

Actually - the highest voltage I get is with the engine off and checking the battery - usually about 12.6 volts. I guess the poor old battery is good.

If I have half an understanding of what this testing means, it looks like the alternator has decided to put out 12.4-5 volts and that's it - enough to run the car and charge the battery until I start loading it with lights and accessories. I need a new alternator is my guess????

Thanks

Dan

 

[440roadrunner]

I had to look at your other posts to find out "who and what" your car is.

These systems are incredibly easy to troubleshoot, but complicated by problems you may have -- mostly in the bulkhead connector -- because of age, corrosion, etc

Here's the simplified diagram of "what you have:"

From this page

http://www.mymopar.com/index.php?pid=78

All in the world that you have is the regulator IGN terminal ---the push on one-- is connected to the "key" side of the ballast resistor. It is fed "switched 12V" or what most of us call "ignition run" also called IGN 1 from the dark blue wire coming from the ign switch.

The regulator gets field power from this wire AND battery "sense" voltage.

So the very FIRST thing to try if the car will not charge is to hook 12V to the field terminal at the alternator to which the green wire is connected.

So the easy way to do this is to run a clip lead from the field terminal of the alternator to the battery stud on the start relay.

I do NOT recommend you simply clip from the alternator stud to the field terminal.

WHY?? Because you MAY have a problem in that charging line!!!

Then bring RPM of the engine up while watching the ammeter, and if the ammeter starts to charge, you can "get an idea" of the health of the alternator by turning on loads, blower, lights, stereo, etc.

You should also monitor battery voltage with a multimeter and don't allow the voltage to go much above 15.5 and certainly not above 16V

IF THIS happens, either the regulator is bad or you have a simple wiring break. To check that out, hook the green field up at the alternator, and unhook the regulator wires, and HOOK THEM together and repeat the test. If the system charges, replace the regulator.

I realize you have a gorgeous restored car, and probably want to retain originality. Probably the best thing is to search for a NOS regulator.

======================================================================

But if the system does NOT charge in the field jumper test..............

The alternator has a problem, might just be bad brushes!!!!

OR you have a problem in the alternator charging wire to the battery.

To check this out, leave the jumper connected to the field, and clip your multimeter:

One probe on the battery positive post (or starter relay stud)

Clip the other probe to the alternator output stud

Bring up the engine RPM again with the field jumper connected. IF the voltmeter shows more than 1 or 2 volts in this test, you have a break or poor connection in your charging wire to the battery

If this shows a low voltage, you can double check to be sure the alternator is NOT putting out

Clip your voltmeter form the alternator stud to ground, and bring up engine RPM. IF the voltage does not quickly climb up towards 15 and more, the alternator is not charging

Please read this article on the hows and whys:

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

The diagram below is from the above page:

I don't for one moment suggest that you bypass your ammeter in such a gorgeous restored car, but heed the "whys and hows" of what might be wrong. This diagram shows the basic path of the charging line from the alternator, through the bulkhead (black wire) through the ammeter, back out the bulkhead (red wire) through the fuse link to the battery.

With the symptoms you have, it is very possible that these connections are still giving trouble. If so, you would have a high voltage reading at the alternator stud while charging, but a relatively low reading at the battery.

 

[RustyRatRod]

On some of the stuff I used to have that wasn't on the street much, I eliminated the amp gauge from the circiut, and that cured 99% of my charging woes. It's a poor design at best, that Mopar routed all power through it. Somebody was on crack when they designed that. Here is what I always do on a street car that requires a gauge.

http://1962to1965mopar.ornocar.org/ml-instrument-voltage-regulator64.html

That will bring it into the 21st century.....well, ok, I mean into the 20th century since all this was available when Mopar designed it in the first place. <rolls eyes>

 

[AR67GTX]

"One probe on the battery positive post (or starter relay stud)

Clip the other probe to the alternator output stud

Bring up the engine RPM again with the field jumper connected. IF the voltmeter shows more than 1 or 2 volts in this test, you have a break or poor connection in your charging wire to the battery

If this shows a low voltage, you can double check to be sure the alternator is NOT putting out

Clip your voltmeter form the alternator stud to ground, and bring up engine RPM. IF the voltage does not quickly climb up towards 15 and more, the alternator is not charging."

OK - I may have run this wrong - I put a voltmeter probe on the alternator output and the other probe on the neg battery post - and got 12.4 V. It never climbed when I reved it up. I think that is the test described in the latter part of the above.

I didn't try from Alt output to pos battery post. This should read less than 1 volt ideally, if I understand correctly.

I doubt it's the bulkhead connectors - at least on the engine side. They are clean but I went ahead and brass brushed the plugs and cleaned the bulkhead with baking soda and water. Then applied dielectric grease and plugged them back in. But they looked good to start with.

I doubt it's the amp gauge because the battery is getting enough juice to stay charged. I drove 15 miles with headlights on last night and the battery was in good shape when I got home.

I guess it could be a bad wire from the alternator to the bulkhead. I need to try checking the voltage from the alternator output to the pos battery cable.

Thanks

 

[440roadrunner]

I probably should have "had you" done the part you just described first.

Now you did try this with a clip lead from the alternator field terminal to battery, right?

If so the alternator is NOT charging.

Once again, it could be as simple as bad brushes

 

[AR67GTX]

I probably should have "had you" done the part you just described first.

Now you did try this with a clip lead from the alternator field terminal to battery, right?

If so the alternator is NOT charging.

Once again, it could be as simple as bad brushes

I ran a clip lead from the alternator field terminal to a ground on the firewall. I didn't run it over to the battery neg post. Same thing?? I felt confident the alternator was bad and pulled it off. Looks like I need to reinstall it and run some more tests. I will clean the brushes before doing so.

 

[440roadrunner]

No you don't ground it to test, you hook the field to a battery source

 

[AR67GTX]

No you don't ground it to test, you hook the field to a battery source

I did some more testing today.

1. Hooked the volt meter up with the pos lead on the alternator power terminal and the negative lead on the battery neg post. It read 12.3 volts. I turned the lights on and it decreased to 11.2 volts. Reving the motor up didn't alter either voltage readings more than a tenth or two.

2. Disconnected the field terminal and hooked the ground lead from the meter to the field terminal and the pos lead to the batter positive post. I got 12.4 volts at idle and 12.1 volts when I turned on the lights. I reved the motor up and the voltage readings were unchanged.

It still appears to me that the alternator just won't put out more than 12.4 volts max.

Dan

 

[ArtH]

12.4 is battery voltage I'm pretty sure 12.6 is what you should have at the battery with nothing running. I would have to say your alternator isn't doing anything at all.

 

[AR67GTX]

12.4 is battery voltage I'm pretty sure 12.6 is what you should have at the battery with nothing running. I would have to say your alternator isn't doing anything at all.

Back a few posts ago you can see that just checking the battery with the motor off I get 12.6 volts. That's the highest voltage reading I can manage to get. But with all this start/stop testing I suspect the battery is not fully charged anymore.

 

[Hemi Rebel]

I did some more testing today.

1. Hooked the volt meter up with the pos lead on the alternator power terminal and the negative lead on the battery neg post. It read 12.3 volts. I turned the lights on and it decreased to 11.2 volts. Reving the motor up didn't alter either voltage readings more than a tenth or two.

2. Disconnected the field terminal and hooked the ground lead from the meter to the field terminal and the pos lead to the batter positive post. I got 12.4 volts at idle and 12.1 volts when I turned on the lights. I reved the motor up and the voltage readings were unchanged.

It still appears to me that the alternator just won't put out more than 12.4 volts max.

Dan

Dan,take a jumper wire from battery positive, and connect to field terminal on alternator. And with engine running,check battery voltage with meter.

 

[AR67GTX]

Dan,take a jumper wire from battery positive, and connect to field terminal on alternator. And with engine running,check battery voltage with meter.

I did this and got 12.4 volts at idle. 12.1 volts with lights on. Didn't change any when I reved up the motor.

Or do you mean jumper wire the field to the battery and check the voltage across the pos and neg battery terminals?

Dan

 

[Sweet5ltr]

I had to run an additional wire to the battery (or starter since it is trunk mounted) when we were having voltage issues. The car would only charge around 11.5V when it should be 13-14V. If it is an everyday driver, eventually this will lead to a dead battery, especially while cranking over a higher compression engine. The factory wiring was not sufficient for even the 65AMP alternator. An easy way to check this is to simply cut a piece of heavy gauge wire, hook it up to the battery post terminal on the alternator (as an addition to the factory wiring) and hook it up to the positive side of battery or even the starter relay if the battery is trunk mounted. If you see your voltage increase, then obviously you know it is your wiring.

 

[440roadrunner]

I did some more testing today.

1. Hooked the volt meter up with the pos lead on the alternator power terminal and the negative lead on the battery neg post. It read 12.3 volts. I turned the lights on and it decreased to 11.2 volts. Reving the motor up didn't alter either voltage readings more than a tenth or two.

2. Disconnected the field terminal and hooked the ground lead from the meter to the field terminal and the pos lead to the batter positive post. I got 12.4 volts at idle and 12.1 volts when I turned on the lights. I reved the motor up and the voltage readings were unchanged.

It still appears to me that the alternator just won't put out more than 12.4 volts max.

Dan

Test 1 shows it's not charging

Test 2 is not a legit test

Dan,take a jumper wire from battery positive, and connect to field terminal on alternator. And with engine running,check battery voltage with meter.

This is what I was trying to get you to do. To be clear, use a clip lead JUMPER not the meter. Disconnect the field wire. Connect a clip lead to the field terminal on the alternator. Connect the other end of the clip lead to a battery source.

THEN see if it will charge. If not, alternator problem. If so, it's regulator or wiring to/ from the regulator.

 

[AR67GTX]

This is what I was trying to get you to do. To be clear, use a clip lead JUMPER not the meter. Disconnect the field wire. Connect a clip lead to the field terminal on the alternator. Connect the other end of the clip lead to a battery source.

THEN see if it will charge. If not, alternator problem. If so, it's regulator or wiring to/ from the regulator.

OK - I did this but my electrical system didn't like it. Lots of sparking when I connected the field terminal to the positive battery terminal. The alligator clip got fried along with my finger. Voltage stayed around 12.4 to 12.5 V except for one brief period when it climbed to about 14 volts for 10 to 15 seconds, but then it fell back to 12.4 V.

Any help?

 

[67 coronet]

do you have an autoparts store near by that can bench test your alternator.best way to be sure is out of the car,and trouble shoot from there.

 

[AR67GTX]

do you have an autoparts store near by that can bench test your alternator.best way to be sure is out of the car,and trouble shoot from there.

Good question. I'll check with NAPA in the morning. I'm about ready to throw a part on this thing.

 

[440roadrunner]

OK - I did this but my electrical system didn't like it. Lots of sparking when I connected the field terminal to the positive battery terminal. The alligator clip got fried along with my finger. Voltage stayed around 12.4 to 12.5 V except for one brief period when it climbed to about 14 volts for 10 to 15 seconds, but then it fell back to 12.4 V.

Any help?

This sounds like trouble in the alternator

What SHOULD have happened is the clip lead should have made a SMALL spark, and IF the alternator was healthy, increasing RPM should have resulted in a "full charge" condition. This is commonly known as "full fielding" the alternator.

I'd say the alternator is bad if you did that right. MAKE SURE you did not get the clip lead hooked accidently to ground

 

[AR67GTX]

This sounds like trouble in the alternator

What SHOULD have happened is the clip lead should have made a SMALL spark, and IF the alternator was healthy, increasing RPM should have resulted in a "full charge" condition. This is commonly known as "full fielding" the alternator.

I'd say the alternator is bad if you did that right. MAKE SURE you did not get the clip lead hooked accidently to ground

My jumper wire uses alligator clips and it's tight down there at the field terminal. It's possible the clip was making contact with the alternator case as the motor was idling. I might try it one more time in the morning by putting a piece of vacuum hose over the clip to keep it from contacting the alternator.

Thanks

 

[AR67GTX]

I insulated everything from ground and re-ran the test this morning. The voltage didn't change at all with the jumper hooked up. Reving up the motor left it unchanged also. I'll check with NAPA for an alternator.

Thanks for the help.