[Goatracer1]

Why would a single wire alternator work in one car and not in another car? I have tried 2 single wire alternators in a 1962 Pontiac and they don't work. They do work in a 1964 Pontiac. Take them out of the 1964 where they work, put them in the 1962 and nothing. Put them back in the 1964 and they work fine. I know that sometimes you have to rev the engine to start them working but it doesn't make any difference. The alternators are 2 different kinds also. First is a Delco not sure what second is. They are wired directly to the large post at the horn relay terminal block.

[stellar]

Since the alts work, that leaves the one wire or the ground. Put a couple of jumper wires from the alt to the battery and see what happens.

[JSchmitz]

How are you seeing/verifying that they aren't working? My first guess would be that it's not getting grounded properly. Try jumper cable from alternator housing to battery ground. Also do a continuity check from alternator housing to ground on block or battery.

[Goatracer1]

Car has a voltmeter and to double check I used a multimeter. I ran a heavy ground wire from the alternator directly to the battery with no effect. Power wire from the battery is same wire used on the other car.

[JSchmitz]

Originally Posted by Goatracer1

Car has a voltmeter and to double check I used a multimeter. I ran a heavy ground wire from the alternator directly to the battery with no effect. Power wire from the battery is same wire used on the other car.

That sure doesn't make any sense. Good luck! How do you have the regulator wire hooked up? Looped back to the terminal on the alternator?

["QUICK-SILVER"]

Are you testing at the battery for charge or looking at the amp meter?

Wired like your doing, the amp meter will show current coming from the battery/discharge, when the alternator is actually charging. That's keeping the battery up and supplying power to the car.

Clay

typing and missed post #4

[Stuart]

Is the 1962 car properly set up for an alternator? In stock condition they were mostly generator cars that year, so the wiring is different.

[george kujanski]

^^^^ this....The generator cars switched the output wire thru the cutoff relay in the OEM voltage regulator. If the original regulator was not bypassed correctly, the alt may not work. Is the output from the alt wired directly to the battery positive?

George

[Goatracer1]

These are ONE (1) wire alternators. The only wire there is a power output wire that is running to the main terminal at the horn relay that the battery's positive cable connects to. I am NOT using an ammeter. Car has a voltmeter installed and I have used both digital and mechanical hand held volt meters. The alternators do not have any output when in the 1962 but using the same wiring (the same actual wires moved from one car to the other) and going to the same place (horn relay) in the 1964 they both work correctly. This type of alternator is used on construction equipment that has no electrical system but is only used to charge the battery. It really should not be this hard.

[stellar]

What is the volt reading at the back of the alternator post.

[Goatracer1]

battery voltage. With just the ignition load on the system it's about 12.3 volts.

[johnta1]

Voltage at the horn relay connection?

Possibly try running the alternator wire straight to the battery?

[Goatracer1]

voltage is the same. It is only about 18 inches from the alternator and the battery. Alternator was connected directly to the battery with no difference. The main POSITIVE battery cable runs directly to the 3/8 inch terminal at the horn relay where a second heavy cable connects and runs to the starter.

[johnta1]

Try a ground wire from alternator case to the negative battery terminal?

It needs a path to the alternator (positive) and a path back to the battery (negative).
Seems you've done everything without making a difference, try the return side now.

[Goatracer1]

I stated earlier that I already ran a ground from the alternators to the battery with no effect. Someday I may find the reason but for now I'm going to run a 3 wire alternator. I should have done it in the beginning but I thought 1 wire would be easier. I installed an old 42 amp 3 wire internal regulator alternator that I had and wired it up. It worked just fine. I checked the Delco 1 wire one and found that on the bottom there was a plug covering the connection for the regulator. I removed the plug and clocked the alternator so that the connection were at the top. After installing the alt. and connecting all 3 wires it charges just fine. Put the other 1 wire alt. back on the 1964 and it charges just fine also. All's well that ends well I guess. Thanks to everyone for the suggestions. If anyone comes up with a definitive answer please let me know.

[johnta1]

This would be one of those occasions where it's easier to check out if there.
Over the internet is not good.

Have any pics of the connections etc?
This wire to alternator is full time 12 volts from the battery?
Just have to ask, is the belt hooked up and spinning the alternator?

["QUICK-SILVER"]

If a one wire alternator needs three wires to work... The internal conversion, that ties B+, voltage sensing and tickle together, has come loose and isn't doing it's job.

If the B+ post came loose or turned, it may have pulled something apart.

If the jumper from B+ to voltage sensing, was made with fussible link wire, it could have blown out.

So something has happened inside if it worked before with one wire and needs three wires now.

That's my story and I'm sticking to it
Clay

[stellar]

I would agree with you Clay except he said it worked on the other car. I also agree with John about it being easier to test if on site instead of on line. Also if the Delco alt was on and a step by step volt reading from specific point to point was done in an orderly progression it may have been solved. When the Delco one wire was on a few simple tests may have revealed a lot. Pics would have been good also. The only other thing I can think of is the alternator shaft speed. Was the engine RPM high enough to excite the alt? If the crank pulleys are different size the alt speed would be different.

[george kujanski]

I was thinking the pulley ratios also.

George

[Goatracer1]

As for the alternators being defective I find it hard to believe Both alts have the same defect. Also BOTH worked when they were first on the 1964 Pontiac and BOTH worked when they were reinstalled on the 1964. As for not spinning them fast enough the instructions state they might have to be rev'd to 1200 engine rpm to start charging. They at one time or another have been rev'd in excess of 2000 rpm. As for pictures all you would have seen was an 8ga wire connected to the output terminal on the alternator(s) running 18 inches over to the 3/8 inch stud on the horn relay and the Positive battery cable running to that same 3/8 inch stud. The voltage never varied from battery voltage (approx 12.3vdc with only ignition load) no matter where I checked it. This is full time battery voltage as you can see. An "0"ga cable at one point was run from the alternator to the negative post of the battery. As for not installing the drive belt I'll admit I'm old and do forget things but even I would not forget to install the belt on 2 different alternators. The only thing different I did to get them to charge was run a battery sense wire and a ignition exciter wire. I've had 3 years of college level electronics and worked as a mechanic (including working for Pontiac) for 30 years before retiring. I consider myself an intelligent person and I have no idea what caused the problem.