1962 Generator system trouble

[superjeannine28]

(1962 bird) "GEN" red light always ON on dashboard. Can anyone help? New Generator, new battery, new voltage regulator. How much voltage should be coming out of the generator at idle? And does anyone know what this tube is next to the regulator (wire from Armature splice).

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[jack-in-sac]

Did you polarize the regulator?

 

[superjeannine28]

No, what does polarizing it do?

 

[jack-in-sac]

Let me start with a correction. The correct expression should have been polarizing the generator not the regulator.
Please correct me all of you cognescenti: If you do not polarize the generator you will not have a proper working generator system. Both the regulator and the generator must be charging in the same "direction" the generator unlike an alternator can charge with either a positive or negative current. the voltage regulator only works with off positive current. If you do not polarize you can damage the charging system.

 

[knuckle47]

Had to polarize the old generators on many vintage bikes. Attach a wire from the A terminal and QUICKLY strike it against the positive battery terminal.

THAT is how I did 1930’s motorcycles…. Just double check. I’m 90% sure it’s the same for you

 

[ak7an]

The "tube" that you are referring to in the picture is called a condensor coil, it is used in the charging system to help eliminate electrical noise that would interfere with the AM radio. Not all cars of this vintage had them as not all had radios.
Take care and good luck
Ed

 

[doug7740]

Polarization is a procedure which matches the polarity for the generator and the voltage regulator. The majority of Thunderbirds are manufactured negative ground, except for the 1955 Thunderbird which was manufactured positive ground. The generator has to be setup for either polarity. The generator will charge either way, however the voltage regulator has only one polarity. After the installation of a battery, generator or voltage regulator follow these procedures.

The terminals on the voltage regulator are labeled ARM, FLD and BAT, and this is where you will do the polarizing procedure. Both the generator and voltage regulator will have battery power, so don’t start the vehicle or turn the ignition on before polarizing them. You will need a small piece of 14 to 16 gauge wire with alligator clips on the ends.

Before starting the car take the short jumper wire and briefly touch the FLD terminal to the BAT terminal to polarize the generator. You can touch the terminals a few times and it will produce a soft light spark. Under no circumstances touch the FLD terminal or any other part of the regulator or you could damage the regulator.

Below is an article I wrote that should answer any questions you have about the battery and charging system on your car.


The charging system consists of the battery and cables, the alternator or generator, and an external voltage
regulator. The function of the battery is to spin the starter motor to start the engine. Once that’s done, the
alternator takes over, satisfying the car’s electrical demands and keeping the battery charged. The battery then
acts primarily as a filter, keeping voltage spikes from damaging the car’s electronics. The voltage regulator
rapidly switches the alternator in and out of the charging circuit to provide the car with the correct voltage.
In 1955, the electrical system of the Thunderbird was 6 volt positive ground. In 1956, the Thunderbird
electrical system was changed to 12 volt negative ground. On the 12 volt system there are two important
numbers to remember, they are 12.6 volts and 13.5 volts.

12.6 Volts: If you think your car has a 12 volt battery, it doesn’t. The 12 volt battery actually has six
individual 2.1 volt cells (one under each fill cap). Thus, when fully charged, the battery should have a resting
voltage of 12.6 volts. If with the engine off, the resting voltage is less than 12.6 volts, the battery is low and
needs to be recharged. Of course, it begs the question of why the battery is low. It could be that the alternator
isn’t working, or that the battery has reached the end of its useful life.

13.5 Volts: With the engine running, the alternator should output a charging voltage that’s about a volt higher
than the resting voltage, or about 13.5 volts. The exact charging voltage may be as low as 13.2 volts or as high
as 14.2 volts.

If your Thunderbird is a 1955, with a 6 volt, positive ground system, the resting voltage is 6.3 volts and the
charging voltage should be about 7.1 volts. The exact charging voltage may be as low as 6.6 volts or as high as
7.1 volts.

Take a multi-meter and set it to measure DC voltage, then measure the voltage across the positive and negative
battery terminals with the engine off. On a 12 volt system, a fully charged battery should read a resting voltage
of 12.6 volts. After you start the car you should see a charging voltage of about a volt higher than resting
voltage. If the reading doesn’t increase by about a volt or if it stays at the resting voltage, it means that the
alternator isn’t recharging the battery. This could be because the alternator is defective, the regulator is
defective, or the wiring between them has failed. In any case, if you drive the car, the battery will run down. If
the battery runs down enough that the ignition stops firing, the engine will stall. It’s really important that you
don’t simply jump-start a car with a dead battery without checking to see if the alternator is charging.
A basic charging system health test: Use a multi-meter to measure the resting and charging voltages as
described above. Then, with the engine running, gradually increase the electrical load by turning on the
headlights and the blower fan. Then increase the engine RPM to about 3500 as you watch the reading on the
multi-meter. If the voltage stays about a volt higher than resting voltage, then the car’s charging system is
functioning. But if the voltage drops or increases dramatically at any point, there’s a problem with the
alternator or the voltage regulator

doug7740
1955 Thunderbird Blue

 

[superjeannine28]

Ok, I polarized the generator. No help. At idle I'm getting 10.3 volts from the generator. And the battery voltage keeps dropping.

 

[Ward 57]

Could the generator brushes be worn to the point they aren't connecting to the commutator properly?
An easy fix and people forget that the brushes are a consumable part that need to be replaced occasionally. Once alternators came along people forgot how generators worked and need occasional servicing. Even modern Kitchen Aid mixers still have replaceable brushes. Just found out my old 60's Kirby vacuum can still be rebuilt with factory parts going back to the 30s.

 

[Frankie the Fink]

One of the advantages of an alternator is they provide decent charging at idle, generators are a bit lame in this regard. So, voltage should be measured at an above idle RPM. However 10.3 V is abnormal, you should see something north of 13.2V at a fast clip. What is the battery voltage with the car's engine stopped ?

 

[knuckle47]

For quick reference my 1956 battery voltage engine off 12.8. Engine running at 800rpm (approx) 13.8-14
I do keep that maintainer on 24 hours a day and disconnected for these measurements
Temp outdoor is 24

 

[doug7740]

As I said in the attached article that I wrote; With the engine running, the alternator should output a charging voltage that’s about a volt higher than the resting voltage, or about 13.5 volts. The exact charging voltage may be as low as 13.2 volts or as high as 14.2 volts.

You said that your getting 10.3 volts from the generator at idle, but does the voltage increase when the engine is running above 2,000 rpms?

Ward57, since they said that the generator is new, I don't think that worn generator brushes are the cause. You are correct that most people don't realize that the generator brushes are wear items.

I disassembled and rebuilt my generator a few years ago, below is a picture of the old brushes compared to a new brush.

doug7740
1955 Thunderbird Blue

 

[superjeannine28]

I charged the battery before starting, it was 12.8v. I just changed the generator, so the brushes should be good. I had someone rev the engine, and I think the voltage from the generator actually went down. The car doesn't have a tachometer (the previous owner did some customizing, I don't know if it originally had one), but I'm going to buy one and see if I can slave it in for testing.

 

[Ward 57]

I charged the battery before starting, it was 12.8v. I just changed the generator, so the brushes should be good. I had someone rev the engine, and I think the voltage from the generator actually went down. The car doesn't have a tachometer (the previous owner did some customizing, I don't know if it originally had one), but I'm going to buy one and see if I can slave it in for testing.

Just because the generator is a new replacement doesn't mean it's a good one. They are a pretty simple device. Where did you source it and do you still have the original? I still think the brushes could be stuck in the sleeves and not pressing on the commutator properly. They also need to be broken in a bit so they make full contact. Maybe even a couple of sharp smacks with a hammer couldn't hurt.

 

[superjeannine28]

Ok I'll take a deeper dive into the generator too. I still have the previous generator, but I don't think it's the original either. Thank you all for your help and input.

 

[doug7740]

I charged the battery before starting, it was 12.8v. I just changed the generator, so the brushes should be good. I had someone rev the engine, and I think the voltage from the generator actually went down. The car doesn't have a tachometer (the previous owner did some customizing, I don't know if it originally had one), but I'm going to buy one and see if I can slave it in for testing.

Don’t worry about getting a tachometer for testing. Since you used a fully charged battery, increased the engine rpm and the voltage went down, that tells us that the battery is not charging.

As I said in the article that I wrote, the problem could be could be alternator, the regulator or the wiring between them. You said that you replaced both the generator and the voltage regulator, why did you replace both of them and do you still have them? Assuming that the wiring is not the problem; wouldn’t it be easier to put the old voltage regulator back on the car and see if the battery starts charging before you put the old generator back on?

I understand what Ward57 is trying to tell you about the brushes being stuck in the holders, but smacking the generator a few times with a hammer is not the proper way to fix it. I really have a problem with smacking any electrical component with a hammer, but maybe that's just me.

When I rebuild generators and starter motors, I replace the brushes and the brush springs, and make sure that they move freely in the holders before I reassemble them.

doug7740
1955 Thunderbird Blue

 

[knuckle47]

Doug, …..That cracked me up. My grandfather always smacked the TV when I was a kid and it stopped that vertical roll

On the other hand, if you car was modified some or customized, check the continuity of these few wires, my ‘56 has been surprising me at several spots with wiring “interruptions” and I have changed several harnesses with great results

I have literally bumped a series of wires and have things turn on or off

 

[Ward 57]

Reminds me of an old lesson; A businessman has a breakdown on a vital production machine and calls in a repair tech. The tech looks over the machine for a bit and returns with an 8lb+ hammer, takes a swing and with a big whack the machine takes off.
That will be $1000 dollars sur. A grand for just hitting my machine replies the owner? The price is $200 for the service call and $800 for knowing where to hit it...

 

[jack-in-sac]

Don’t worry about getting a tachometer for testing. Since you used a fully charged battery, increased the engine rpm and the voltage went down, that tells us that the battery is not charging.

As I said in the article that I wrote, the problem could be could be alternator, the regulator or the wiring between them. You said that you replaced both the generator and the voltage regulator, why did you replace both of them and do you still have them? Assuming that the wiring is not the problem; wouldn’t it be easier to put the old voltage regulator back on the car and see if the battery starts charging before you put the old generator back on?

I understand what Ward57 is trying to tell you about the brushes being stuck in the holders, but smacking the generator a few times with a hammer is not the proper way to fix it. I really have a problem with smacking any electrical component with a hammer, but maybe that's just me.

When I rebuild generators and starter motors, I replace the brushes and the brush springs, and make sure that they move freely in the holders before I reassemble them.

doug7740
1955 Thunderbird Blue

View attachment 20995

Doug, just a note of correction. We are referring to a generator not an alternator. Just mental typo?

 

[jack-in-sac]

This could be even stickier if it were a early bird. there are often core charges for rebuildable items to insure a supply of rebuildable cores. I have had more than one person buy a replacement generator and turn in the "core" from their Thunderbird. When they go to install the replacement generator they discover the little bird plate is clocked differently than the one they got as a replacement. The T-Bird end plate is not the same for passenger cars and T-Birds.