1 wire alternator

I am in need of a new alternator. I was looking at a 1 wire type. Other than having to rev it high on initial startup (that is all I assume, at idle the jeep is at 700-800 rpm and would still charge) any other issues that would keep me away from a 1 wire model? The current one I have has dumped on me (no voltage on the volt meter, then 13 volts, then none, then 10, all over the place). It is over 20 years ole and had been rebuilt, but I would feel safer with a new one. well anyways, any need to stay with the 3 wire kind?
Paul

 

Here's a good article describing the pros and cons of each:

http://www.madelectrical.com/electricaltech/onewire-threewire.shtml
http://www.madelectrical.com/electricaltech/delcoremy.shtml

I'm very happy with my 3-wire

 

so in wiring up a 3 wire, I should have the voltage sensing far away from the Bat post. My confusion is where the excite wire taps in. I know it should go to the ignition switch, but which connection? ACC, start, or ignition/run?
I have an alternator already hooked up, but how can I check to see if the wires are correct? The wires were spliced. I can figure out the sense wire I think, just by seeing if the number 2 terminal connects to a wire from the bat post. There is also a wire that goes to the volt meter on the dash.
If I turn the ignition switch to ignition, without starting the vehicle Just before turning over the engine), should I read a voltage in that wire?

 

Here's a sample wiring diagram where they wired the #2 to the battery:

Connect it to the ignition/run switch.

If you turn the ignition on, you should see 12v on #1. You should also see 12v on #2 because it is probably connected at a point that is "hot" all the time.

 

I am really happy with my one wire.
Once you rev her up to 1700 rpms or there abouts she charges.
That is a fast idle with the choke set.

 

I greatly prefer the 3 wire set up over the one wire. I had a 10 SI wired as a 1-wire. I use the winch a lot with the engine idling. After stoping and starting the engine, I did not always remember to rev the engine to excite the alternator. This also happened when starting and stoping the engine doing repairs. PIA when you kill your battery this way. When I found a larger output alternator, I wired it as a 3 wire. No more problems. best mod I've made. Very simple to convert a 1-wire to a 3 wire. This was discussed in a thread started by Matt Winkler last year. http://www.earlycj5.com/forums/showthread.php?t=84603&highlight=alternator&page=7

CO64CJR summed up steps on page 7 of the thread as follows:
CO65CJ5
Sorry, I couldn't come up with a snappy tune to go with this. There are actually a number of options involved, but since it's a 3-wire alternator we can boil it down to three steps:
1. Run a wire from the BAT terminal on the alternator to the battery. This is the "charge" wire.
o This should be a heavy wire, at least 10Ga, preferably 6-8Ga. Heavier is better but don't be silly.
o The most common place to connect this is the battery terminal on the starter "solenoid".
o For safety, this wire should be fused at the end electrically nearest the battery. A fusible link is usually used, but other fusing options are available.
2. Run a wire from the #1 terminal on the alternator to a switched, current-limited 12-volt source. This is the "excite" wire.
o This can be a lighter-gauge wire, like 16-18Ga.
o Normally, this is connected to the charge indicator lamp in the instrument cluster. The other side of the charge indicator lamp goes to the "IGN" terminal on the ignition switch, or equivalent
o If you don't have (and don't want) a charge indicator lamp, you may want to add a resistor or resistor wire. Something like 10-30 ohms should be OK.
o If you have electronic ignition, or in some cases even with points-type ignition, the engine might continue running after you turn off the key. This is because the alternator can "backfeed" into the ignition system through terminal #1. If this happens, add a diode in series with this wire. Get a 3-amp diode, and install it with the banded end toward the alternator.
3. Run a wire from the #2 terminal on the alternator to the battery. This is the "sense" wire.
o This can be a lighter-gauge wire, like 16-18Ga.
o In most cases, you can just connect this to the BAT terminal on the alternator. If you see too much voltage drop at the battery, you can run this wire to the battery (or equivalent) instead.
4. Optional, but a very good idea: Run a heavy wire (same size as the charge wire in step 1) from the alternator's grounding connection (a threaded boss in the back of the alternator) to a grounding point on the engine block.

OK, so that's four steps, but it's not really a 3-wire alternator . . .

Oh, and don't forget to rinse and spit.


Look for subsequent threads started by Matt to see what to do with regulator wires.

 

Hopefully this isn't too dumb of a question...

If I have a one-wire alternator but plan to run a voltmeter vs ammeter, do I still run a wire off the alternator pigtail (not the red battery wire, but the other one that the schematic shows as running to the instrument cluster)?

Thanks!

 

Volt meter can pretty much go any where you want it.

Good spot is if you have the battery cables that have the little pigtails on them for doing that kind a thing. Then you are reading the voltage right at the battery.

Or you could run both and amp guage and a volt meter.

 

Thanks for the response! Do I have to hook anything to the wire I referenced?

I'll hook the volt meter to the battery as you suggested.

Appreciate it!

 

You might want to hook the voltmeter up to a switched power location like the ign switch, otherwise it will be reading the battery voltage 24/7 and it will eventually drain the battery.

 

I bought a 100 amp 1-wire unit from Summit a couple years ago. It's worked great from an electrical standpoint, but the bearings went out after about a year. $15 bucks of replacement bearings from NAPA & it works just fine. I think mine starts charging at about 1300-1400 RPM, which is a non-issue for me. BTW I'm running an AutoMeter volt meter-after having an electrical fire caused by a cheap ammeter shorting out, I don't trust them anymore.

 

I got a 100 A 1-wire Alt from an EBay store and its given me several years of trouble free service. I’m pretty pleased with it.

Heh, I had the exact same problem on two different vehicles. Well, one I can’t blame on the ammeter so much as the mice that ate their way into my car through the soft plug leaving bare wire rubbing against the firewall. The ammeter is just where the fire started.

 

I would have to go out and trace my ammeter before I can tell you where to hook it up.

Plus you need one that is rated at a higher amperage than your alternator is rated.

 

How many amps is enough? Powermaster has a 140 amp model that can be 1 wire or hooked up as 3 wire. I read it is never a bad thing to have extra amperage. I was looking at the model 8002 and 47294. The 47294 is 140 amps and can be 1 or 3 wire. according to their site I would need a 6 gauge charge wire. Not sure what my current wire is, I have an EZ wire set. One last thing, looks like the charge wire goes to the starter solenoid and the other devices connect there. Is this setup adequate?

 

You mean to the big terminal that the plus cable from the battery is hooked to?

 

let me take a closer look. There are 3 posts right. The Batt which should have the battery positive. There is another wire (maybe 2). I assume one is the charge wore from the alternator. The other is ?voltmeter ? The other terminals, I for ignition should run to the ignition on the ignition switch. The R should have a wire running to the HEI distributor. Therefore it should have 4-5 wires attached to it right? I will need to remove the battery tray to get down there and get a closer look at the solenoid. Tight in the engine bay.

 

I am getting to the party pretty late here. What Make model and Year did you order the Alternator for? FLAPS has trouble looking up anything that they dont have all that info for. Thanks

 

Regarding the amperage capacity. My original Motorola alternator ('70 225 OF) was rated at about 35 amps. That's pretty low for anything other than the bare basics. The unit I replaced it with (NAPA Gold) is rated for about 80 amps. That's been more than enough for me. Most people tend to recommend more capacity - maybe 100 amps. I'm not sure what I'd do with all that amperage?

The MadElectrical web site has great info.