[scapegoat]

I have a carbed sbc in an s10 with a one wire alternator. My battery was charged up pretty well and I went around the block a few times varying the rpm. When i got back to the house I hooked up the trickle charger to see i the battery was fully charged. I took over an hour for the charger to say its done charging! Is my alternator working? Its brand new from jegs. I didnt drive it that long, maybe ten minutes. I have the one wire from the alternator going to the positive terminal. But I also have two more wires hooked to this terminal on the alternator. One goes to the battery gauge in the cab and the other goes to a distribution block looking stud on the firewall. When the truck is running the battery gauge say its charging. Does this gauge measure the alternators output or the battery condition? I just want to figure this out before I take it for a long ride. Thanks fellas.

[T-bucket23]

You need to put a meter across the battery when it is running and see what the vlotage is. It should be between 13.8 and 14.2 volts once the alternator has been spun up fast enough to start working.
Those 1 wire alternators are not as good at maintaining battery health as a 3 wire. It sounds like you would have been all set for a three wire, why did you decide to get a 1 wire

Chet

[302 Z28]

I agree with "T-Bucket", you would have been better off with a 3 wire. One wire alternators are definitely easier to wire up, but that is about it. FWIW, I can drive my 34 with a 3 wire and then pull into my garage and hook up my battery tender. It will not go to trickle for about 30 minutes.

Vince

[scapegoat]

I have a 3 wire but I was leary about hooking it up in the s10. It is a newer alternator from a sbc. I didnt know where to hood up that white two pronged plug that comes from the alternator. The one wire I have I bought because its a pollished unit from jegs and it looked nice and the wiring didnt look confusing. I just went out and started it and the gauge inside the truck was more than half way up. Its the stock s10 volts/amps or whatever it says guage. I have a mutimeter but it is confusing as hell. I have yet to teach myself how to use one. I can rebuilt engines to no end but a multimeter will stop me in my tracks

[malc]

Worth posting once again, One Wire versus Three Wire alternators.

[scapegoat]

Here is that alternator that I have...

http://www.jegs.com/i/JEGS/555/10105/10002/-1

I do have a regular three wire. I just don't know where to hook up the two pronged plug that is on it.

[75gmck25]

This URL has information on how to switch from a 1 wire to a 3 wire alternator.

How do I wire a 3 wire alternator when I used to have a 1 wire alternator???

Bruce

[arizray]

If you are talking about a GM self-regulated "one wire" alternator here is how I wire it. From the output post I run 8" of #12 fusible link attached to a #8 wire that terminates at the starter/battery connection. This setup assures that the will be no difference of voltage when measured at the alternator and the battery. Additionally the two wire plug on the alternator needs to be wired as follows. The #1 terminal terminates at the alternator output post along with the previously wired #8 wire. The #2 terminal is attached to a 1 amp diode and connected to a ignition-only 12v source, preferably within the vehicle cab. The diode has to be wired such that current flow is towards the alternator. This connection tells the alternator what the real-world demand of the system is and thus regulates the alternator output to match that demand.

Note that proper grounds between the chassis, engine and frame are as important.

[captbuick]

OK, I've read the M.A.D. article. And i'm somewhat of a dummy so, I want to stay with the three wire system. So somebody explain in 8 year old terms what wire goes where, and do I have to run an idiot light or can I leave that wire unhooked. This car had a generator with a new harness that I would still like to use. Any help? Thanks

[T-bucket23]

You need the light wire to excite the alternator. The other small wire is the sense wire that should be connected somewhere near the fuse box to properly sense and allow the regulator to adjust.

Where in the Boston area are you. I am in Worcester if you need some help.

Chet