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Alternator wiring

Discussion in 'Flat Fender Tech' started by Lifesgoodhere, Feb 22, 2009.

  1. Feb 22, 2009
    Lifesgoodhere

    Lifesgoodhere Like 6 Jeeps isn't enough

    Staunton, Virginia
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    Ok so im trying to wire up my alternator here. I think I have it right, but not 100% sure. CHECK MY WORK!

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    The engine turns off when the key is turned off. When the engine is idling, my voltmeter (hooked to the battery) reads 17 volts to 21 volts. When I rev the engine up to around 2000 RPM, the voltmeter reads 13.7 solid.

    I guess the battery is charging, but why the volts so high at idle?
     
  2. Feb 23, 2009
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    cordele, Ga.
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    You dont say wheather your running a coil w/internal resistor or external ballast?

    The Grey/white wire from starter is indicated as going to two diff places (acc on key - ign on key). If it is in fact going to the Ign "ON", you will burn points. The red wire from "Bat" term on alt should be increased to a 10 ga size and I would run it directly to the starter solenoid with the battery cable connection. The grey/white wire at that location would need to connect to the BAT term on ign switch. Are you running an ammeter-volt meter- or a gen light ind? (any type of charge indicator) HTH
     
  3. Feb 23, 2009
    Lifesgoodhere

    Lifesgoodhere Like 6 Jeeps isn't enough

    Staunton, Virginia
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    I will be running a volt meter.

    I don't know how to tell if the coil is internal resister or external. How can I tell. their are no markings on it. The coil came off my 12 volt f-head engine (was running a generator)

    I am just mocking stuff up, I will be replacing with 10 GA wire.

    so i should have the black wire (gray) with the 3 tracers in the "IGN" in key? Their are 2 black with 3 tracers, but one is a dead wire, used for the 6 volt regulator for a 6 volt generator system. The alternator is internally regulated, and was bench tested by a shop and showed it producing 13.7 volts across the board..
     
  4. Feb 23, 2009
    CO64CJ5

    CO64CJ5 Member

    Littleton, CO
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    As Walt mentioned, the 10GA wire from the alternator's BAT terminal should run to the battery connection on the starter.

    The rest of your wiring is still a bit confusing. In your first picture, there is a blue splice in the wire connected to terminal 1 on the alternator. Does this splice contain a diode or resistor, or is the wire itself a resistor wire? If so, connecting it to the ignition coil's "+" terminal should be OK.

    In the last picture, there appears to be a blue wire connected to the terminal you've labeled "BAT". Where does the other end of this wire connect?

    I don't know what to make of the black/white striped wire running from the keyswitch ACC terminal to the battery. :?

    Here's how I think it should be:

    10GA wire from alternator's BAT terminal to the battery connection on the starter.
    Wire from starter's battery connection to the keyswitch BAT terminal.
    Wire from keyswitch IGN terminal to coil +
    Wire from coil + to alternator #1 terminal. This wire should have either a diode or resistor in it.​

    If you have an "AMP" light in your speedometer, this last wire could go to that light instead of the coil.

    17-21 volts will not make your battery happy. That's enough to fry most electrical items you might have in your JEEP. The internal regulator uses terminal #2 to sense the charging voltage. In your picture, it looks like you have this connected to the alternator's BAT terminal, which should be OK.

    The behavior you are describing is perplexing. Often, perplexing behavior results from bad grounds. Although I don't see how that would explain this, it is worth noting that the alternator is grounded to the engine through its frame. If the mounting bracket you are using is painted, it might be worthwhile to wire a ground from the alternator to the battery grounding point. This should also be at least 10GA.
     
  5. Feb 23, 2009
    Lifesgoodhere

    Lifesgoodhere Like 6 Jeeps isn't enough

    Staunton, Virginia
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    ANSWERING THE QUESTIONS IN ORDER.

    The that wire is just a wire. 12 GA I believe. I am going to need a diode, but not sure what to get.

    -----------------

    That blue wire is for the electric fuel pump. I am going to wire it into the "BAT" terminal on the key, and then use a flip switch to turn it off and on.

    ------------------

    I ran it that way because that wire is the hot wire. It goes to the starter switch. I put it their so that when i turn the key off the engine turns off because the hot wire would kill power to the ignition system.

    ------------------

    Yes the bracelet is painted. I have read that you run a ground from the alternator VIA threads for a short bolt on the back of the alternator, to the battery ground clamp



    ************

    Now, the "sense wire is being jumped to the stud on the back of the alternator. In some of the wiring diagrams I looked at it showed it should be done that way. From the stud the wire that ultimately leads to the "BAT" terminal on the KEY.

    OK do you know what resister/diode I should use?

    SO for my voltage gauge, it replaces the "AMP" light? is that right?
     
  6. Feb 24, 2009
    DAUNTLESS46

    DAUNTLESS46 Member

    SO CAL
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  7. Feb 24, 2009
    DAUNTLESS46

    DAUNTLESS46 Member

    SO CAL
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    heres another dia[​IMG]gram i foun in another thread
     
  8. Feb 24, 2009
    Lifesgoodhere

    Lifesgoodhere Like 6 Jeeps isn't enough

    Staunton, Virginia
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    I was told that was wrong
     
  9. Feb 24, 2009
    Lifesgoodhere

    Lifesgoodhere Like 6 Jeeps isn't enough

    Staunton, Virginia
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    opps I posted a question about this in the "Alternator Upgrade..." thread.
     
  10. Feb 24, 2009
    CO64CJ5

    CO64CJ5 Member

    Littleton, CO
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    I may be assuming too much, but let's see. I'm not that familiar with the 3b, so some of this is educated guessing. I assume, since you have a foot starter, that your keyswitch has three positions: Off, Acc, and On. The terminals on the back of this switch would be labeled something like "BAT", "ACC", and "IGN".

    The BAT terminal should connect to the starter switch, where the battery cable is connected. This provides power to the switch.

    The ACC terminal should connect to anything which should receive power only when the key is on, whether or not the engine is running. This would be things like turn signals, radios, etc.

    The IGN terminal should connect to anything which should receive power only when the engine is running. This would be the ignition coil, fuel pump, and alternator field.

    In reality, you could swap the BAT and ACC terminals and it should work the same. That appears to be what you have. To me, this is confusing, because the labeling is contrary. I would wire it as I have described above, just to make it easier to keep straight.

    You may have special reasons for doing this, but if it were mine, I'd wire the fuel pump to the IGN terminal and leave out the toggle switch. This way, the fuel pump will be powered only when the engine can actually be running.

    Yes, there should be a threaded hole on the back of the alternator which can be used for a ground strap.

    This is the simplest place to wire it. The "ideal" place to connect it would be the battery connection on the starter switch, but if you use at least a 10GA wire from the alternator's BAT terminal to the starter switch, it won't make much difference.

    As shown in the diagrams posted by DAUNTLESS46, about 10-15 ohms. Forget about the diode, it's probably a needless complication. If you use an AMP light, you probably won't even need a resistor -- the light is a resistor. If you don't have or want a light, use a resistor. For testing purposes, you might try connecting terminal #1 to the coil + with a test light, just to see its effect.

    Not really. In the sense that it tells you how your alternator is working, yes, but the light has a side-effect of providing a current-limited voltage to the alternator's field windings to enable it to start generating at idle. Without this, you will need to rev the engine to get the alternator to "start". In fact, if you don't mind revving the engine like this, you could even get away with leaving terminal #1 disconnected. This wouldn't be my choice, but that's just me.

    Both of these diagrams are basically correct, but the "Jeep CJ charging circuit" diagram shows a starter solenoid, which you obviously do not have.
     
  11. Feb 24, 2009
    Lifesgoodhere

    Lifesgoodhere Like 6 Jeeps isn't enough

    Staunton, Virginia
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    ok...i'll take this information and correct my wiring tomorrow. Thanks for the help. I guess "idiot" light which is for the lights will work fine.
     
  12. Feb 24, 2009
    CO64CJ5

    CO64CJ5 Member

    Littleton, CO
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    ??
    If you mean to use the high beam indicator as an AMP light, you could hack this up to work, but I wouldn't. For one thing, it already performs an important function. For another, it's wired wrong -- one end is grounded. The AMP light connects to the IGN terminal on the ignition switch, not to ground.

    If this is not what you mean, then never mind.
     
  13. Feb 24, 2009
    Lifesgoodhere

    Lifesgoodhere Like 6 Jeeps isn't enough

    Staunton, Virginia
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    I do not have an amp light. My mistake about the beam indicator...tell tail light it called..
     
  14. Feb 24, 2009
    LarryD

    LarryD Member

    Gallup NM/ 4 Corners
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    . When the engine is idling, my voltmeter (hooked to the battery) reads 17 volts to 21 volts. When I rev the engine up to around 2000 RPM, the voltmeter reads 13.7 solid.

    I guess the battery is charging, but why the volts so high at idle?[/QUOTE]

    17 to 21 volts will damage the battery. I don't know of a situation where you have more voltage at idle than at 2000 RPM. I think the voltmeter has 2 terminals on the back. I believe they are marked + and -. Make certain they are connected correctly and that the + terminal is not grounded on the gage case.

    My alternator is set up so that you must rev the engine when you first start the engine to start the charging cycle. When I first start the vehicle it reads 12 1/2 volts, after I rev the engine the alternator kicks in and goes to 14.4 volts.
     
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