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Voltmeter vs. Ampmeter

Discussion in 'Early CJ5 and CJ6 Tech' started by Boyink, Oct 6, 2007.

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  1. Boyink

    Boyink Super Moderator Staff Member

    Never had a voltmeter in a Jeep before...getting ~15V when running. That about right?
     
    Boyink, Oct 6, 2007
    #1
  2. packrat2A

    packrat2A Member

    A little high, but within specs for most rigs..
    Is it analog or digital? Assuming analog:
    check it with a multi-meter to make sure its not just the guage reading a little hi.
     
    packrat2A, Oct 6, 2007
    #2
  3. Jeepman252

    Jeepman252 Sponsor

    14 or so is pretty typical.
     
    Jeepman252, Oct 6, 2007
    #3
  4. Boyink

    Boyink Super Moderator Staff Member

    Analog.

    Should it be the same as reading across the battery?
     
    Boyink, Oct 6, 2007
    #4
  5. Jeepman252

    Jeepman252 Sponsor

    Yes, here is a very simplified wiring diagram for a volt guage.
    [​IMG]

    So, the reading across the battery should be the same.
     
    Jeepman252, Oct 6, 2007
    #5
  6. Boyink

    Boyink Super Moderator Staff Member

    Getting 15.6v across the battery.

    New battery.

    Fresh wiring job.

    New battery == down a bit on charge, or do I suspect my alt regulator wiring?
     
    Boyink, Oct 6, 2007
    #6
  7. Walt Couch

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

    New wiring? Sounds like the alt is being full fielded and overcharging battery. Should be regulated charge voltage of 14.6 + or - with or without lights radio etc.
     
    Walt Couch, Oct 6, 2007
    #7
  8. Boyink

    Boyink Super Moderator Staff Member

    Once again, in English please? :)
     
    Boyink, Oct 6, 2007
    #8
  9. Boyink

    Boyink Super Moderator Staff Member

    And here's something that's been bugging me since I bought this thing. The motor is a 1990 4.3 Chevy. Wouldnt that use an internally-regulated alternator? Can you tell by looking at one if it is?

    Pics of the alternator and regulator attached.

    I'm half-tempted to yank the alt. and get an internally regulated one or a one-wire just to simplify things.

    Oh - I also get 12.9V at the battery when engine not running.
     
    Boyink, Oct 6, 2007
    #9
  10. Jeepman252

    Jeepman252 Sponsor

    Jeepman252, Oct 6, 2007
    #10
  11. Boyink

    Boyink Super Moderator Staff Member

    :shock:

    I love pages like that. Titled "Alternator" but the text keeps saying "AC Generator". I've never heard an Alternator called that - but Googled the term and see that they are the same thing. Why not just call it a danged alternator....:rofl:

    I have neither an inductive ammeter or carbon pile, and I don't know if my alter...uhh..AC Generator is an "A-Circuit" or "B-Circuit" (and they don't explain the difference or tell me how to tell)...so still not sure what to do after reading that.

    Looking at the manual that came with the wiring harness, they show feeding the alt exciter wire to 2 terminals (3&4) on the external regulator. The Jeep came with only terminal 4 connected, so that's how I wired it. Could that be the issue?
     
    Boyink, Oct 6, 2007
    #11
  12. Vanguard

    Vanguard Take Off! Staff Member

    Mike,

    I don't know what kind of alternator you've got there. Doesn't look like a Delco 10 or 12SI. I know those are internally regulated.

    Any idea what that is?
     
    Vanguard, Oct 6, 2007
    #12
  13. Boyink

    Boyink Super Moderator Staff Member

    "temporary", as far as I'm concerned...R)

    Really...no clue. It's pretty new - sticker still on it. Why you'd put an externally regulated version on a new motor is beyond me though.
     
    Boyink, Oct 6, 2007
    #13
  14. sammy

    sammy Coca-Cola?

    I didn't read the article on Autozone, nor do I fully understand terminology, but someone was having the same problem a while back on here, too much voltage and someone replied with a bad voltage regulator or ground or some sort?
     
    sammy, Oct 6, 2007
    #14
  15. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    With that high a voltage, we could assume that the alternator is running unregulated, ie 'full field.' An alternator produces AC, which is rectified to DC. The faster it runs, the higher a voltage it will make AFAIK... higher dB/dt and all that. I would suspect the external regulator...

    Joe Guilbeau's writeup may be more to your taste. http://www.offroaders.com/tech/Alternator-Theory.htm
     
    timgr, Oct 6, 2007
    #15
  16. lamar

    lamar Member

    that alternator look like the mid 60's to early 70's gm externally regulated type of alternator.
     
    lamar, Oct 6, 2007
    #16
  17. Walt Couch

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

    It is the early model GM Delco (as said 60-70) model. The newer internal reg type delco should fit into same bracket assy with maybe a spacer change. Your old sys (reg) needs a wire from idiot light to reg plus others. Simplify your system.
     
    Walt Couch, Oct 7, 2007
    #17
  18. Strider380

    Strider380 Can I have a zip tie?

    Definitly upgrade to externally regulated. It was the smartest thing I ever did. Took maybe 15 min, after I screwed with the regulator for 5 days.
     
    Strider380, Oct 7, 2007
    #18
  19. org1970cj5

    org1970cj5 New Member

    Here's the Summit P/N for the 1 post alternator I like to use: SUM-811001 cost $82.95. It's 100 amp and all you need is a 8 or 10 guage wire running to your battery.

    Robert
     
    org1970cj5, Oct 8, 2007
    #19
  20. w3srl

    w3srl All-around swell dude Staff Member

    Sounds like it is overcharging just a bit Mike, the battery voltage sounds just a tad high also. Is that the alternator that came on the engine? If so, I don't think that it is OEM due to the external regulator.

    Cheapest and easiest fix would prolly be to replace the regulator if you can source an exact replacement. FWIW every 1990 4.3 application I can find shows an internal regulator...

    <edit>

    A good solution might be a reman 63-amp form your FLAPS Mike, they only run about 30 bux. And the 3-wire is really pretty simple to wire up, you truly only NEED two wires to make it work.
     
    Last edited: Oct 8, 2007
    w3srl, Oct 8, 2007
    #20
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