Alternator

Posted by john in la on November 15, 2004 at 05:39:12 from (66.157.27.124):

In Reply to: Ford Hundred Series 12V Conversion (very long) posted by john in la on November 15, 2004 at 05:32:11:

4) Alternator
You will be replacing your 6v generator and external regulator with a 12v alternator with internal regulator. There are several choices but this set up calls for a Delco 10SI 3wire alternator. They make a 1 wire alternator but I feel the 3 wire set up is far superior. You can see more info on this subject at M.A.D. Enterprises web site. I use a 9 o-clock set up since the alternator mounts on the left side of the engine. This means when you look at the back of the alternator with the adjusting bolt straight up the wires will hook at the 9 o-clock position. This makes for easy mounting of the wires. If your parts man can not find the part with this info tell him you want a alternator for a 1979 Buick Regal, 8 cylinder 4.9L (301W) engine, with air conditioning. The Delco part # is 321-41 and a lot of part places have it listed under the generic # 7127-9. This will give you a 63 amp 9 o-clock Delco 10SI alternator.

Testing;
The battery terminal on the back of the alternator gets hook to the large battery post on the starter relay. So it has power all the time. This is the wire that charges the battery.
The #2 or S (stator) spade was originally hooked to power in the wiring harness to compensate for voltage drop in the wiring. With a tractors small wiring you can just connect it to the battery post on the back of the alternator via a short jumper wire. This wire tells the alternator when the charge is enough and shuts the regulator down as not to over charge the battery.
The #1 or F (field) spade gets hooked to the terminal block with power only with the key on. It energizes the alternator on start up so it will start charging. This wire is the dreaded night mare of the conversion so lets look at it in detail.
A lot of people do not understand how it works so they try all kinds of stuff to correct problems it can create. In fact many just leave this wire off and only hook up the above two wires. It will work like this; but as I said before you need to rev the cold motor all the way up to get the regulator to leak enough energy to start the alternator to charging. Some have even tried to put a smaller pulley on the alternator so it will spin faster at lower rpm’s.
The 1 wire alternator uses a different regulator so it will leak enough energy at a lower rpm and only uses the wire that connects to the battery terminal; but like I also said I do not feel it is worth $70.00 just so you can leave these two wires off.
The problem lies in the fact that this #2 wire gets hooked to the terminal block in the same spot as the coil. Once the alternator starts to charge it will back feed power back through this wire. When you turn the key off to kill the motor it will not shut down since the coil is being fed from this power. So we need to find some way to send power to the alternator through this wire on start up but break the back feed of power to the ignition system.
So how can we do this?
Well since you only need to supply the power to the alternator for a few seconds to get it to start charging I have seen some people that put a toggle switch or a starter/horn button in this wire. You would start the tractor and hit the button for a few seconds to start the alternator to charging then let it go. The alternator will continue to work as long as the tractor is running and when you shut it off the button is the break in the wire you need to shut down the motor. Problem is you need to remember to push the button every time you start the tractor. NOT LIKELY….
So we could go to Radio Shack and get a POWER diode. This allows power to go one way but not the other and works automatically. No buttons or switches to remember about. Ask for part # 1N4003. I think these diodes sell for about $1.00. While part # 1N4001 is a smaller one I have heard that people have been using this one also with no problems. The diode must be hooked up the correct way. The cathode end goes toward the alternator. This end is usually marked in some way such as a white band. You can test it by hooking it up and turning on the key with the motor off. If you have power on both sides it is hooked up correctly. If not turn it around.
But wait the 601/801 has a dash warning light and that is the way GM set this system up to work in the first place. See if we put a small 2 wire 12V light bulb in this wire it will work like it was originally set up to work. Power goes from the terminal block to the light and then out the second wire to the alternator. This makes the light come on but leaves enough power to energize the alternator so it will start charging. Once the alternator starts to charge it back feeds power to the light. Since the power is the same on both sides of the light it goes out and lets us know the alternator is charging. When we turn off the key this light bulb comes back on because it has power coming from the alternator but not the key. This happens so fast you may not even see it but it is enough to stop the back feed of power to the ignition system allowing the coil to stop firing and in turn shutting down the motor.
If you do not have a 601/801 and do not want to drill a hole in your dash for the warning light but would like one that is possible also. All you need is a small trailer clearance light that does not ground through the case but grounds through a second wire. You can mount this any where under the dash. You may not be able to see it from the seat but it does its job of preventing back feed and if you suspect it is not charging a quick look at the light will tell you.

Follow Ups:

• Re: Alternator john in la 04:44:57 02/27/05 (0)

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