OT: Alternators

On a common GM alternator what are the 2 terminals comming out of the side for. I assume the large stud terminal goes directly to the battery and I was told 1 of the side terminals is used to excite the alternator and this can be accomplished by running a keyed + through an indicator light and then to one of the terminals. Anyway which terminal would it be and what is the other one for.

Reply to
habbi
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I've changed three tractors over to GM alternators (from generators). While I don't know why they have two, wire both together and then to a switched 12 volt source. I'm sure it both provides power to windings and does the voltage regulator.

If you're using the same spot on the key switch that also provides power to the coil, you'll need to add a diode or the engine won't shut off when you turn the key off. Cost is $1 from rat shack.

You're correct, the large stud goes to the battery.

Karl

Reply to
Karl Townsend

One of the small studs is 'exciter' power from the ignition switch to turn the unit on, the other one hooks up to the "Idiot Light" circuit and I believe it also serves as a voltage sense lead. Don't ask me which is which, I'd have to find a reference book.

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Reply to
Bruce L. Bergman

One plug in terminal excites the alternator with battery voltage through the ignition switch, the other goes to the alt light on the dash. Newer versions don't have these plug in terminals. They are commonly refered to as one wire alternators. They are the best thing since sliced bread for retrofits to almost anything needing an alternator.

Ron Thompson Was On the Beautiful Mississippi Gulf Coast, Now On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

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Reply to
Ron Thompson

I assume that your US alternators follow the same design as our UK ones. There are 3 connections. The BIG one is straight to battery and carries the charge current. The small one labelled W/L supplies the initial excitation and is fed with ignition live via the warning light. This light also stops the alternator putting enough current back down that wire to keep the engine running when you switch off. The other small connector should be labelled + or S is a sense lead. This should be connected to the battery in parallel with the big wire. It is there to sense the voltage at the battery without being confused by the voltage drop in the main current wire.

John

Reply to
John Manders

There are three types of alternators from GM. There are wiring diagrams available for using those alternators on some of the old car sites - I remember that there is a Chevelle site that had some generator to altenator conversion info and images.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Reply to
Bob May

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