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One wire alternator, now battery dies?

Discussion in 'The Garage' started by Jrgunn5150, Jun 25, 2006.

  1. Jrgunn5150

    Jrgunn5150 1/2 ton status

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    Hey guy's, I put a Summit one wire 100 amp alternator on my beast a few weeks ago, it was the only change. All I did was remove the stock alternator and braket and replace it with the one wire/March bracket that's on there now. I took the wires from the plug on the old alternator and shoved them up by the firewall, and hooked the positive battery cable to the stud on the alternator.

    Now something is drawing my battery dead, and fast. It will die in a 8 hour period while I'm at work. Is it the alternator? Or is a one-wire really require other wires moved around or something? It wasn't happening before the swap. Also, I have a 6 month old Optima yellow-top in the truck, and it's a 86 Silverado with a 350/700r4.
     
  2. greyhoundjc

    greyhoundjc 1/2 ton status

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    You should only need the one wire. Sounds like you have it set up right (as long as you have the wire hooked to the right stud, some alternators have a ground stud). I would stop by Autozone or the like to have the alternator checked. May be a bad unit. I've gotten bad alternators before. This won't fix the problem but I have heard that when going to a single wire setup, it's best to hook the power wire to the top post of the battery. Thats what I did. Good luck!
     
  3. greyhoundjc

    greyhoundjc 1/2 ton status

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    I just re-read your post and am I understanding that the battery dies while the truck is sitting?
     
  4. Jrgunn5150

    Jrgunn5150 1/2 ton status

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    Yes, when I leave the truck, it's like the alternator is drawing the battery dead somehow. It wasn't doing this before the swap.
     
  5. 70jimmy

    70jimmy 3/4 ton status Premium Member GMOTM Winner

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    The reason your battery is being drawn down is because the wire that goes to the alternator should be controlled by the ignition switch to only draw power when the switch is on.

    The positive battery cable would still go to the starter and the little lead off the cable would hook up to the same wire that you had prior to the swap (if you had one.) If you didn't have one I would look at wiring diagrams in a manual to see what wire the positive small lead should be hooked up to. Mine goes into a batch of wires that go to the driver's side and connect into a group that ultimately goes to the fuse panel.

    On the old wiring to the stock alternator you should have had a plug with wires and one wire that went to a stud on the old alternator. Hook the old stud wire on the stud on the new alternator. I think I had to put a larger end on the wire to fit the new stud on my one wire.

    My negative battery cable connects to the alternator bracket and there is a ground wire under it that connects to the frame. Hope I made it clear as mud!:rolleyes:
     
  6. ntsqd

    ntsqd 1/2 ton status

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    Normally one of the wires going to the alt turns it on with the IGN. The charge light is an indicator that the alt is consuming power and not charging. Once charging the light goes out b/c the alt feeds 12V to what was the ground side of that light (don't worry, it's not an internal short).
    You DO NOT want charge current going thru the IGN switch. That would be BAD.

    With a one wire regulator what turns it on is the small self-excitation that happens when the stator turns, but isn't energized. One wire regulators are sensitive to this small voltage and they will turn on with it. From the desciption the wiring was done correctly, but something is wrong with that regulator and it isn't turning the alt off when rotation stops. Talk to the maker or seller, they should fix it.
     
  7. 4by4bygod

    4by4bygod 1/2 ton status

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    Something summit doesn't tell you

    Engines with one wire alternators need to be revved to about 1500 - 2000 rpm in order for the alternator to begin charging. Just blip the gas once, you should be good to go. If you just low speed or moderately cruise it without revving it once, it won't be charging while you are driving, giving you the dead battery.

    Personally, I don't think they're worth the hassle, but that's just me.

    Tom
     
  8. Jrgunn5150

    Jrgunn5150 1/2 ton status

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    It's not that it isn't chargin while driving, it does a great job of that, it's that it is drawing the battery dead rather rapidly while it is sitting (engine not running). I can't imagine how you can hook up a one wire alternator wrong, but if there is a way, I'm dumb enough to find it.

    I will call Summit this weekend and see what their tech guy's say (they made the alternator), although I haven't found them to be very helpful in the past. It is close enough to me that I can just drive down there and exchange it though fortunately.
     
  9. ntsqd

    ntsqd 1/2 ton status

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    I think an exchange is what you're looking at. Basically that same circuit that turns the not charging light on in a multi-wire alt. isn't turning off in your one-wire alt. when the engine stops.
     

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