Cheque out my "Gallery", you should be able to see how my Alt. is installed.

 

No, the GM 3-wire is the same alternator as the one-wire except without the modifications to eliminate the other two wires. Both have the main power wire in common and both are internally regulated. The other two wires in a 3-wire are for a ground and a wire that goes back to a warning light. I'm using a voltmeter and I wanted the warning light on the dash just in case the alternator quits charging. You might not notice that on a voltmeter but a red light in your face is pretty obvious.

 

I personally don't like those GM 1 wires. They maybe easier to install but they have no voltage sensing ability like the Ford 3 wire. We normally have to get the 90 amp GM alt on our tractor rebuilt 3 times a year (it's not from the dirt either). At idle (on the tractor) with no accessories on its puting out like 15.2v. Turn on the A/C, then it's 14.4v. Sometimes we just turn on the lights and when the voltage drops to 11.5 you know you just fried the alt. Our 65 and 69 Fords still have the factory alts and regulators. Better yet would be a 130 amp 1-wire Ford alt from a Crownvic.

 

If ford would put out a single wire, of course I'll be buyin that one. The ease and clean look of the GM is just the way to go...until something else comes along.

 

Something's wrong with that GM, I would fire your rebuilder! They do indeed sense voltage, at the point that the single wire is connected. Do you have the case of the alt grounded well? Are you using a #10 or larger output wire? It actually sounds like it has no regulator! My 1-wire is rock-steady from idle to 2000 RPM, varies only with battery condition (i.e., higher after a lot of cranking).

 

Ok,

you're gonna have to esplain what "Voltage Sensing" is........

 

Umm, well reading it, I am assuming it works like a voltage reggy, and when the voltage gets funny, it senses it and cuts.

 

Well the circle is complete then.......I need an alternator that has a regulator built in.

A single wire GM alt. Or a 3 wire GM alt. (With the reg built in) Or one without the reg built in........at which point I'll simply build my own regulator. Life is all about choices!






"and when the voltage gets funny, it senses it and cuts."

A good discription of a Voltage regulator.

 

The three wire GM alternators I have used have a large red wire that goes to the battery "+". A small red wire that supplies power from a hot wire when the ignition is on to turn the alternator on with the key no reving up the motor to get the alternator to turn on. The last wire is a sensing wire in the fact it can be moved back to where the majority of the current draw comes from. Such as a junction in the wiring where the heater and headlights both meet. That way when the headlights are turned on the voltage drops and the alternator ups it voltage internally. That setup allows the alternator to put out say 15.5 volts internally to keep that junction at the headlights at 14.4. A single wire alternator should put out ~14.4 volts all the time no matter what. It is using the single wire that it is connected internally to get the reading for voltage. As an example if the headlights drop down to 13.5 volts due to losses in wiring etc the alternator does not care it will continue to put out 14.4volts and leave the headlights and at 13.5 volts where the externally sense wire would prevent that. From my understanding that is why you do not see everything with a single wire alternator. A high current draw system would continue to draw more current lower the voltage and the alternator would never see that it is only connected to the battery and does not know what the rest of the vehicle is doing.
Kind of like having a thermostat in one room of a house. You get some rooms that are warmer and some that are colder. But that one room where the thermostat is is always correct. The sense wire relocates the thermostat to a central part of the house so all the rooms heat closer to the same.

 

Gosh! I told my evil twin to stay off the computer!!! I don't know what I was thinking when I wrote that. Umm but uhh yeah....Oh, sorry, somebody is giving me a call. Gotta run!

 

A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. It may use an electromechanical mechanism, or passive or active electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.With the exception of shunt regulators, all voltage regulators operate by comparing the actual output voltage to some internal fixed reference voltage. Any difference is amplified and used to control the regulation element. This forms a negative feedback servo control loop. If the output voltage is too low, the regulation element is commanded to produce a higher voltage. If the output voltage is too high, the regulation element is commanded to produce a lower voltage. In this way, the output voltage is held roughly constant. The control loop must be carefully designed to produce the desired tradeoff between stability and speed of response.
HAPPY????

 

Or you can take your Ford Alt to your rebuilder and they can convert it to a one wire. And it will be all Ford.

 

High current low voltage switching power supplies are designed that way.

Anytime you have a high current application you have the problem of voltage drop (due to high current) in the feed lines. (This is the reason automotive engrs went to 12v and have considered 24 and 48 volt systems.) It may be due to actual resistance or voltage drop across switches and connections.

I had a couple of 300A 5 volt switchers that actually had 2 150A, 5 volt units wired in parallel in one box and were adjustable from about 4 volts up to about 8 volts.

I rewired them in series and used tham as 150A 14v power supplies. They had remote sensing also.

They were incredible. With a 120A load the voltage would only drop 0.1V!! (measured with my wonderful Fluke 189!)

Of course depending on the length/resistance of the feed wires the actual power supply voltage would increase to keep the voltage at the load nearly exactly at the "set" voltage.

They also had over voltage and over current protection (fold-back).


I love the internet. Here's a great discussion on 1, 2, and 3 wire alternators.
http://www.alternatorparts.com/what_...alternator.htm




I don't really care what kind of a car my alt came out of!

Cheers,

Rick

 

Okay, took a snap of my alternator setup. For the record, I didn't do it! It was like this when I bought the truck.



It's hard to see the machinist rule in the pic, but it's 1.25 inches out of alignment. I'm gonna be making new brackets and spacers soon. The one wire deal sure is nice though. I never could figure out how to ground or polorize the voltage regulator!

 

Thanks, fellas, I think...I'm so confused...