460 alternator

tleake

Member
Okay, I puzzled! I bought a 460 some time back and it has been converted to 12v alt. 2 wires coming off it. Idecided to clean up the wiring nightmare a bit.
1 wire goes from the stud on the alternator back to the battery side of starter solenoid.
The other wire goes from the alternator to a switch on the dash then to the hot post on the battery. I was told this was either to keep the battery from being drained by the alt. I was also told that switch was there to send power to excite the alternator???
Can anyone clarify this for me?
 
FYI, there is no longer a voltage regulator under the fuel tank, am uessing the alt has a built in?
 
We are working with a 3 wire set up by the sounds of it. Yup one wire to the amp gage from the Alternator Bat terminal then one from the plug to the bat terminal the 3rd to your switch then to 12 volt at the amp gage starter solenoid or such. I can't remember which of the 2 wires goes to the bat terminal from the plug right now.
 
In general you have the "main current" which is the stud which eventually goes to B+.

Then you have "excite" and "sense" terminals, usually spade lugs.

Excite is +12vdc as you state, and "sense" is examining the same voltage as the B+.

I personally find it strange but true that all 3 connections could be jumpered together and it would all work.....Except the excite terminal would drain the battery when the engine is off. Enter diodes and resistance elements (lamps) which cut off the return path of current.
 
Who ever rewired it before bypassed the amp gauge completely. Just 2 wires coming from the altenator. one from the stud to battery side of starter solenoid.
The other wire is on one of the spades and goes to a toggle switch on the dash then to the battery stud. There is another spade on the alternator but it has not been used.
I am guessing they would start the tractor and flip the toggle to excite the alternator then shut off that switch when they shut down the tractor???
I am thinking that would overcharge the battery. I am going to get it operational for now and worry about a factory harness when I get around to doing a restore on it.
None of the original wire is in place, I am thinking it shorted and they did a farmerneering job on it to get it going again.
 
I assume you have the Delco 10-SI with internal regulator. You have Batt (stud where the heavy wire attaches to charge the battery) and two spade terminals recessed in the rear cover. If these two are indexed up at 12 o'clock, the left one is terminal 1 which should be connected to battery voltage. The volts on this terminal ultimately drive the regulator to output the correct voltage. The right is terminal 2 and this should be coming from the key switch (as switched power...dead with key off, hot with key on). This terminal is the initial excitation for the fields. On an idiot light system, the initial excitation is thru the idiot light's ground. The light glows because it is grounded thru the field coils. As the alternator output rises, the internal excitation voltage rises until the voltage is the same on both sides of the light. Same volts? Then no current flow and the light goes out. Some people simply jumper between batt and term 1. This does not allow the regulator to adjust for wire resistances and bump up the voltage to compensate. Delco likes it sensing closer to the battery, however, the jumper typically is fine. I would not wire term 2 directly thru the key switch but rather thru a resistor in series with the switch and term 2.(the light bulb is acting like a resistor) It will be no problem to wire direct IF the key switch has enough capacity to carry the full load of field excitation plus any other loads (like ignition, lights, etc) If unsure, I would wire thru a resistor and not direct.
 

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