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changing from 2 wire alternator to 1 wire..question

Discussion in 'The Hokey Ass Message Board' started by FoxSpeed, Apr 6, 2012.

  1. FoxSpeed
    Joined: May 19, 2009
    Posts: 385

    FoxSpeed
    Member
    from NorCal

    I am switching to a one wire alternator on my 327 engine. I have a voltmeter. I understand that a 10 gauge wire from the alternator batt terminal to the starter solonoid is all I need to do. My question: Obviously the 2 wire alt has two wires. What do I do with these? Thanks
     
  2. FoxSpeed
    Joined: May 19, 2009
    Posts: 385

    FoxSpeed
    Member
    from NorCal

    Thanks, that is what I will do.
     
  3. brokenspoke
    Joined: Jul 26, 2005
    Posts: 2,874

    brokenspoke
    Member

    check out ( madelectricial )
     
  4. Why would anyone want to go 1 wire. They do not charge at low rpm.
     
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  5. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,103

    Mr48chev
    ALLIANCE MEMBER

    Some don't charge well if you just start the rig without revving up the engine to get them to start charging. After firing the rig up an giving the engine a quick rap they usually kick in and charge at an idle. Some of the others have a one wire box on the plug on the back that works as an exciter.
     
  6. Incorrect, they do charge at idle and low rpm. But you must excite them first.
     
  7. sickytwisted
    Joined: Feb 2, 2009
    Posts: 140

    sickytwisted
    Member

    I love excited alternators!
     
  8. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,796

    tfeverfred
    Member

    What's the advantage?
     
  9. LostHope
    Joined: Jul 9, 2008
    Posts: 687

    LostHope
    Member

    Also if you didnt know you dont have to go buy a 1 wire GM alternator you can turn your GM 3 wire into a 1 wire by adding a jumper wire like this:
    [​IMG]
    you dont have to run the IND. wire to the number 1 post.
     
  10. sickytwisted
    Joined: Feb 2, 2009
    Posts: 140

    sickytwisted
    Member

    Is this true? That's kinda awesome!
     
  11. Hemi Joel
    Joined: May 4, 2007
    Posts: 728

    Hemi Joel
    Member
    from Minnesota

    In my experience, the only reason to use a one wire alternator is to avoid running the extra wires. If the wires are already there , Why would you want to switch to a one wire and live with all of its drawbacks?
     
  12. Hemi Joel
    Joined: May 4, 2007
    Posts: 728

    Hemi Joel
    Member
    from Minnesota

    I've been wrong before, but I don't think that will work.
    To be a "One wire" alternator, it needs to have a self exciting regulator built into it. If it has a self exciting regulator it only needs the one wire to the battery. If it does not have a self exciting regulator, It must have switched 12 V power to the number one terminal or it won't work.
     
  13. malcolm1943
    Joined: Sep 28, 2011
    Posts: 239

    malcolm1943
    Member

    hemi joel,
    what drawbacks, I've run a one wire for the last ten years and have never experienced a single problem, and by the way, in those ten years, I've only changed batteries once!
     
  14. Hemi Joel
    Joined: May 4, 2007
    Posts: 728

    Hemi Joel
    Member
    from Minnesota

    Well, I don't mean to rip on the one wire alternators, I've used them plenty over the last 17 years since I got my first one. But the 3 wire is easier to live with, it's cheaper, and easy to find a replacement if it fails out on the road. One potential advantage of the 3 wire is that you don't have to rev it upon initial start up. That has been an issue for me for 2 different reasons: on a daily driver with an automatic choke that I want to warm up on high idle in the morning I floor the gas and let off to set the choke, start the engine, and it idles at 1300 rpm or so. Well, that's not enough to excite the alternator. If I gas it enough to kick in the alternator, the high idle cam on the carb drops back to a slow idle. So I need to let the car warm up with an inoperable charging system. Similarly, on my hot rod hemi with massive valve spring pressure, when I start it cold it takes several minutes of warm up time before the oil is warm enough to get out to the rocker tips. To avoid damage I need to idle it till it warms up. If it had a one wire, it would be warming up on battery power.

    Also terminal 2 is a remote voltage sensor for the internal regulator. It tells the alternator what voltage it needs to produce to keep 14 volts at the ignition switch, instead of maintaining 14 volts at the alternator. This usually results in a hotter ignition and brighter lights.
     
  15. sickytwisted
    Joined: Feb 2, 2009
    Posts: 140

    sickytwisted
    Member

    This thread got confusing for me:confused:
    Is the wiring diagram supposed to show what you would do to swap the externally regulated alternator to an internally regulated alternator? Yes?
     
  16. LostHope
    Joined: Jul 9, 2008
    Posts: 687

    LostHope
    Member

    Ive been running it like that on my truck for the past two years ! works for me.
    Unless my trucks been running on my battery for 2 years?

    now im wondering ill have to check my truck in the daytime....I might have the IND light hooked up???....Sorry If I made a wrong statement,scratch what i said tell I report back after I look at what I did on my truck...
     
    Last edited: Apr 9, 2012
  17. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    tommy
    Member Emeritus

    Wow, I'm not alone.:D I can understand using one if you are scared shitless about electrical stuff when you build a new car but I can't understand changing an alternator just to get a one wire unit.

    I think about the poor guy that was cruising around the fairgrounds all day starting and stopping only to have his new battery go dead because he never got up enough Rs to excite the alternator. I don't get the attraction. But then again I removed a freshly rebuilt alternator to rebuild and run a generator on my 56. most people won't get that either.:D
     
  18. TrioxinKustoms
    Joined: Oct 16, 2009
    Posts: 551

    TrioxinKustoms
    Member
    from Romney, WV

    this is the set up I'm using on my 60 lincoln. I used the alt off of my old
    86 cadillac I had hanging around. Charges great and I tied it into the original idiot light.
     
  19. Retro Jim
    Joined: May 27, 2007
    Posts: 3,860

    Retro Jim
    Member

    Personally if you have the original wiring harness and it's in good condition and your alt goes up , then replace it with what you had before ! Why change it to a 1 wire . That make no since to me at all ! :confused:
    Now if you are changing a 6v to 12v charging system that would be a good reason to get a 1 wire alt., BUT just to replace your 2 wire alt with a 1 wire is just plain stupid !

    Retro Jim
     
  20. Hemi Joel
    Joined: May 4, 2007
    Posts: 728

    Hemi Joel
    Member
    from Minnesota

    The setup shown in that diagram will work, as long as the wire is hooked up to #1, but that's not really a covversion to a 1 wire is it? What that diagram shows is how to simplify the wiring harness but defeat the remote voltage sensing terminal. If you experience any dim headlights, especially at idle, hooking that #2 wire up to your ignition switch, or the hot lead on your headlight switch will help.

    Just to clarify, since this gets so confusing:

    The big fat terminal with the stud and nut is where the the alternator puts out all the juice it makes. It gets connected with a heavey wire to the battery cable at some junction point like the starter solenoid. On a 1 wire alt, this is the only terminal that gets used.

    The #1 terminal on the little connector provides switched 12v input from the ignition switch that exites the alternator instanly upon start up, and it (optionally) operates an indicator light that is placed between the ignition switch and the alternator. In an alternator with a self exiting regulator, this wire is not needed. (1 wire alternator)

    The #2 terminal provide voltage sensing for the internal regulator. This tells the regulator how hard it needs to work to keep up 14 volts. The car manufacturers realized that there is voltage drop between the battery and/or alternator and the electrical loads, due to resistance in the connectors, fuses, and undersized wires that they use to save $. So they run this wire into the harness somewhere in the dash, downstream from a lot of the resistance - that way the alternator trys to maintain 14 volts at the fuse box or the ignition switch. (which could mean that it is making 16v at the alternator) If you connect this wire right to the 12v terminal on the alternator, or use a 1 wire system, the alternator maintains 14v at the alternator, regardelss of any voltage drop throughout the wiring harness.

    Most 1 wire alternators still have terminals 1 and 2, and they will function if connected. If you are having issues, you can use terminals 1 and 2, just like in a 3 wire and they serve there functions.

    This stuff all seemed so mysterious to me, and I used a 1 wire everywhere to avoid the other wires. Then I bought a new one wire from a local rebuilder to put on an old tractor that had a magneto, and thus no wiring. But it wouldn't charge because the tractor engine would not rev high enough to exite it. When I brought it back, the shop owner explained the whole thing to me. Now it seems so simple, just knowing where the other 2 wires go and what they do, I always use them.

    I hope this helps, Joel
     
  21. It's the only thing I excite these days.
     
  22. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,478

    sunbeam
    Member

    Some electonics products don't like one wires because of voltage spikes.
     
  23. The pic shown works great and is the way to wire in an alt if your going from a gen or aftermarket harness BUT it's not a true wire alt (Hemi Joel is correct). I have a 1 wire alt on my flathead (po installed), I personally don't like them or any other way of eliminating the warning light (via diode or just ign switch). The 1 wire are more expensive, a little harder to find and why wouldn't you want to have a warning system?. You can hook up a volt meter to a 1 wire system, but not a warning light and a warning light you can hide anywhere............under the dash, in a gauge cluster, on the dash, in a dome light...it's endless.
     
  24. el caballo loco
    Joined: Mar 7, 2012
    Posts: 166

    el caballo loco
    Member
    from colorado

    What 48 said. Mine charges fine at idle BUT i do hafta blip the throttle to wake it up on startup. : )
     
  25. You do realize that there's a pill for that.
     
  26. RatPin
    Joined: Feb 12, 2009
    Posts: 573

    RatPin
    Member


    Good info!

    I found though that my alternator is a 1 wire even though it was sold to me as a 3 wire. I had it hooked up as a 3 wire and was wondering why my acc. terminals were hot 100% of the time even with ignition off and keys out. Well I guees on the 1 wire alternators both of those terminals (1&2) are hot all the time and my exciter wire that was plugged into the #1 terminal was back feeding power to my fuse panel thus keeping my acc. leads constantly hot.

    So I guess my options are to keep the terminal unplugged and taped off with a 1 wire setup or go find me a true 3 wire alternator. I bought this brand new at the swap meet:mad:. Is there a way to test whether an alternator is 1 or 3 wire out of the box?
     
  27. threewindow
    Joined: Nov 26, 2012
    Posts: 80

    threewindow
    Member

    I make my three wire a one wire by putting a jumper wire inside the alternator. never have any problems with idling. works just fine.
     
  28. Clik
    Joined: Jul 1, 2009
    Posts: 1,829

    Clik
    Member

    My lights dim and brighten even at highway speeds. Could this be due to the alternator that the previous owner replaced the generator with? It only has one wire hooked to it.
     

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