Converting 1 wire to 3

I posted a little while back about my one wire alternator not charging my Super 55. I took it in and had it tested, and it was good. They couldn't help me on converting it back to 3 wire so.... I have the pluging for the side, I don't need the warning side. I have the meter, the switch to excite it when im on the tractor, and the fuse. I'm confused on how to wire it up so everything works. Does the main wire go through the gauge to tell me if its charging? What about the wire to excite it. Like I said I have a switch so I don't kill my battery when I turn off the tractor.

<img src = "http://ndtc3500.stellarnet.com/~blweltin/Bob/AlternatorHarness4.jpg">

The large output wire will go to the ammeter. The lead from the battery will be alone on one ammeter terminal stud, the alternator's output wire and ALL electrical loads on the other. (If it reads back wards, swap the wires between the two posts.)

You can use the diode, as shown, or an "idiot lamp" or a 10-Ohm, 10-Watt resistor in the "switched excite" lead. Any ONE of those three choices will work equally well. Connecting it up that way provides a safety factor for the alternator, as well as eliminating the need for an extra switch to remember to shut off.

Are you still using the "one-wire" alternator?

In general, that will proably work, although there MAY be exceptions to those working 100% properly when set up as "3-wire" units.

Matt, most "one wire " alternators will work as a 3 wire alternator which begains charging at low idle. all you need to do is get a replacement delco alternator plug to prevent wiring shorting to the alternator case, from an auto parts store for about $2.
You connect the #2 alt plug wire to the BAT stud on the alternator rear, and connect the #1 alt plug wire through a small indicator light to 12V power that turns off with the ignition switch. The indicator light serves two purposes, it eliminates alternator "backfeed" to the tractor wiring, and it indicates that the alternator is charging.
You do not need to wire in an ammeter unless you want the meter to indicate charge rate, the light is telling you that it is charging.
With the light, you only need a 10 guage wire from the alt BAT stud to a battery connection ( where ever the hot battery cable attaches to the start switch /solenoid.)

If you do want an ammeter, you must connect the alternator output and all electrical loads (ign switch, lights etc) to one ammeter post and a 10 gauge wire from the battery connection to the other ammeter post. If the ammeter reads backwards, switch all wires to the opposite ammeter post.
With these wiring mods, you can use any 1 or three wire alt on your tractor.

Bob has you covered on this one. Just look at his picture and flow what he said to do and you will be up and running in less then an hour
Hobby farm

Its now charging. One other question. I am worried about the battery draining. I used an indicator light for the resistance, and I now have my ampmeter wired up. I do show a charge now, which it never did before. My tractor doesn't have an ignition switch, its a diesel with the old push rod starter. How do I know if I have the switch wired correctly. When the switch comes on, should the little light come on? Thanks. Matt

yes, switch on, tractor not running, the light should be on.

When the tractor starts, possibly needs to rev up a bit, the light should go out.
The indicator light tells you that the excite circuit (#1 wire) has power before the engine starts, then goes out to tell you the alternator is charging.
Some wire the excite circuit and indicator through an oil pressure switch, so the circuit is broken when the stopped engine has no oil pressure.
No chance of forgetting that and discharging the battery.
Lots of two terminal pass through oil pressure switches used to power electric chokes or electric fuel pumps in pickups / cars.
My 80 GMC 6 cyl pickup had one for the electric choke.

Something aint right then. The switch doesn't do anything. One side of the switch runs through the light to the alternator. Does the other go to the battery? I have f2 connected to the battery terminal on the alternator. I have the other wire going into the switch with the light attached. Does the other post of the switch go to the battery?

Yes, the other side of the switch should be attached to the battery hot lead through a fuse.
When you turn the switch on with the engine not running, the light should be on.

I put a 3 wire Delco on a 88 Olivar diesel years ago. The way I handled the switch to energize the alternator was a HOBBS SWITCH in the engines oil pressure line. When the engine started the alternator energized and when you shut the engine down there was NO switch to remember to turn off to keep from running the battery down.

Kent

Well either way its charging. If the switch is on or off. Is that because of the alternator being self excited? The little light works as it should when the switch is on. It goes off when running. The amp gauge works now also. Once again thanks!

Yep, the self exciting alternator will excite without exciter current from the warning light, usually at a little higher rpm though.

The odd thing is that most standard 3 wire alternators will also self excite if you spin them fast enough.