The Stovebolt Site Forums The Shop Area The Electrical Bay Going From A Generator To An Alternator

I am in the process of having my 235 with a generator swapped out with V8 with an alternator. I bought a wiring conversion that has the plug and single wire for it. The mechanic that's doing the swap tells me that I don't need this wiring conversion, all he needs to do is run a wire from the hot battery cable to the single stud on the alternator. I asked him what about the plug on the alternator, again he says it's not needed, since the wire from the hot cable will charge the battery and the wiring is already there for the volt meter running off the starter. I'm no electrician, but sometghing tells me the plug in the back of the alternator has a purpose. Can somebody shed light on this for me? Thanks

Years since I dealt with this. That stud on the generator is the output to send current to recharge the battery.

The plug in wire connector is input voltage to feed the rotor. No voltage supplied to the rotor no magnetic field created to induce current in the stator. No current induced in the stator no output from the generator.

Your mechanic sounds like he should be in the fertilizer business. He could supply his own product by talking to the delivery trucks!

Only one of the two terminals on the outer perimeter of the alternator needs to be connected, unless you plan to run a "no charge" warning light. Connect the red wire on the connector to the big terminal at the back of the alternator and run a heavy (#10 or bigger) wire from there to the battery + terminal. The brown wire on the 2-pin connector can be used as a ground for an idiot light, with the power for the light connected to ignition or accessory voltage.
Jerry

Thanks for the replies.....It's time I said enough of this garage and bring my truck home, even though it's not done.

After another garage SNAFU this past Thurs, I brought my truck home on Fri! I'll finish it in my garage.

Your story reminds me of my uncles car. Uncle never could afford new or low mileage cars.

He lived 1 hour away from us. Out of desperation he called us for his charging system stopped working. I think he had a 1968 - 1969 full sized 4dr Pontiac.

I think he had a generator still. The hack he brought the car to said his external voltage regulator was missing 2 wires. Remember the electrical harness connector was sized to hold 4 wires. Though I think they used 3 wires if I remember right.

So uncle brought the car to us to look at. I saw that the connector only had 2 wires. I checked back along the harness and on top of the engine looking for disconnected wires. None found.

This Pontiac was close to being 15 years old and it looked as if nothing was changed. So I told my uncle this charging system looked original and was working with just 2 wires since it was new. I see no missing wires.

I said let me see if I can find out. Now at that time I was going to the GM Training Center in Tarrytown. So while there I found the AC Delco instructor. Right away he knew what I was talking about.

He pulled out a 4 page instructional booklet and said for a short while the cars with an ammeter only had 2 wires running to the external voltage regulator. Then he showed me how that system was full field tested.

Regulator tested bad. I put in a new GM regulator at the mechanics/employee price 10% above cost.
Jeffrey

If the alternator was set up as a 1 wire alternator, then the mechanic might have been right.

There is not enough residual magnetism in the rotor for the AC generator to induce current in the stator. There has to be a wire to supply the rotor with voltage. Jeffrey

I cannot find clear advice in this thread (probably due to my ignorance).

If Cablesmill has a one-wire alternater, it has/needs only one wire. I installed one on my friends 12v 1954 pickup 18 years ago and it still works fine. If you want the wiring "diagram", I'll post an old illustration that I found on the Internet almost 20 years ago.

A one-wire alternator is "self-exiting" - it needs to reach a certain RPM to start charging - mine started at about 800 RPM, but I have read of some that need 1200 RPM to get "exited". Once the 1-wire alternator is "excited", it charges at all RPM.

Usually, when you start a 216/235/261 engine, you use a choke and the engine reaches 800-1200 RPM when it is started, so this "excitation" reality/problem is no problem.

As I think was posted above. A 2 or 3 wire alternator has a dummy-light lead and an alternator-"excitation" lead (neither of which are needed with a one-wire alternator). Yes, I have seen the M.A.D. Enterprises' website's information on alternators. They do not like 1-wire alternators - many years ago, I stopped loosing sleep over their knowledgeable opinions.

http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

My one-wire alternator cost much less than any alternator they were selling many years ago.