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Thread: how many volts should the alternator put out??

  1. #1

    Post how many volts should the alternator put out??

    I've been having troubles with my headlights burning out prematurely. I was thinking that the alternator could be putting out too much voltage and thus heating up the bulbs too much. I checked the voltage last night. With the Jeep off, but the ignition in the on position the battery read 11.90 volts. with the Jeep on and at idle or upto 3000 rpm the voltage was at 14.9 volts. 14.9 seems to be too high, what do you guys think. Do you think this could be a problem for any of the other systems in the vehicle??

    TIA

    Steve

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    '90 XJ 3.5" with 30X9.5 BFG AT's on AR 767's, 3" coils and spacer from rusty's and RE AAl with MJ shackles. Rusty's Cat-back with flowmaster 3-chamber, air tube with K&N filter, Tuffy security box, Hella E-Codes 100/80W with custom harness, Hella 500 driving lights 100W bulbs, Rusty's tow hook's and brackets, JKS Gen II disconnects
    To be installed: Rusty's transfercase skid, Rusty's motor mounts

    non-jeep photos
    '90 XJ 3.5" with 30X9.5 BFG AT's on AR 767's, 3" coils and 3/4" spacer from Rusty's, RE AAl with MJ shackles. Rusty's Cat-back with flowmaster 3-chamber, air tube with K&N filter, Class 3 hitch and Warn Reciever shackle, Tuffy security box, Hella E-Codes 100/80W with custom harness, Hella 500 driving lights 100W bulbs, Optima Red Top and 160 Amp alternator, Rusty's tow hook's and brackets, JKS Gen II disconnects, Rusty's motor mounts, Rusty's transfercase skid, C4x4 double-tube rocker guards, HI LIFT
    Jeep Pics

  2. #2
    Registered
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    Oct 2000
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    Santa Ana, CA, USA
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    Post

    it takes 13.5 to begin to charge the battery, 14.1-5 is about normal. 14.9 is getting up there, my personal limit is 15.0.

    ------------------
    Brian Stroud
    01 Jeep Grand Cherokee Limited Up Country

    http://users.deltanet.com/~stroud
    Brian Stroud
    01 4.7L Jeep Grand Cherokee Limited Up Country

    Kolakized
    70 Series Flowmaster, Mike Leech 3 inch tailpipe, K&N FIPK, TeraFlex 2 inch (BB), 265/70/17 BFG TAKO's, OME stabilizer, IAS Shocks, Brnasi IAT Tweeker , Brnasi FIPK RamIT! Ram Air System available at http://members.cox.net/brnasi-engineering/

    6.63 0-60 (best)performance

    other cars include a sub 9 second 70 Keith Black RB 528ci duster, a 12 second 77 440 Dodge B van, both built by myself, and an 01 Dodge Quad Cab Ram 4x4 with off road package

  3. #3
    Registered John V.'s Avatar
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    Sep 1999
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    California, San Diego, USA.
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    Post

    Does your dash mounted voltmeter agree with the direct to battery meter? If so, you should be able to watch the dash meter voltage taper down to about 13.5 to 14 volts after you driven for a while, if it stays at 14.9 something could be wrong. How old is your battery? Regards, John V.

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    John V San Diego, Calif.
    White 1995 Grand Cherokee, 4.0L,F-Package, K&N drop in, 3.75" franken lift (TeraFlex front lower control arms, rancho coils, Daystar and home made spacers, longer Bilsteins, home brew bump stops, JKS Quicker Disconnects) 31X10.5" BFG AT KO's, custom transfer case skid (home made), factory gas tank skid, home made rock sliders, 4Xdoctor diff guards, Rusty's Tie rod, Hella 500's. Link to more of my Jeep stuff and "how to" photos http://albums.photopoint.com/j/AlbumList?u=141119
    -------------------------
    Also BMW R80 RT (Beemer) with Velorex Sidecar (love to fly the car)

    [This message has been edited by John V. (edited 12-18-2000).]
    John V San Diego, Calif.
    Current wheeling videos

    Flop recovery at Gatekeeper Calico -- OUCH!
    http://www.youtube.com/watch?v=osy9XTY1N5A
    Anza Borrego Heart Attack Hill
    http://www.youtube.com/watch?v=_bScAe7rjsU
    Dusy Ersham Trail with 12 Hr tow out
    http://www.youtube.com/watch?v=NuIwv...e=user&search=

    Glow-in-the-dark Yellow Rubi LJ, Nth* 6" kit, Auto, 35's with 5:13's
    And when we have company in town and DD,
    ZJ with mostly home-made armor and 4.75" Franken-lift.

  4. #4

    Post

    I have a '90 XJ with the "idoit lights", so I don't have a voltmeter.

    Steve

    ------------------
    '90 XJ 3.5" with 30X9.5 BFG AT's on AR 767's, 3" coils and spacer from rusty's and RE AAl with MJ shackles. Rusty's Cat-back with flowmaster 3-chamber, air tube with K&N filter, Tuffy security box, Hella E-Codes 100/80W with custom harness, Hella 500 driving lights 100W bulbs, Rusty's tow hook's and brackets, JKS Gen II disconnects
    To be installed: Rusty's transfercase skid, Rusty's motor mounts

    non-jeep photos
    '90 XJ 3.5" with 30X9.5 BFG AT's on AR 767's, 3" coils and 3/4" spacer from Rusty's, RE AAl with MJ shackles. Rusty's Cat-back with flowmaster 3-chamber, air tube with K&N filter, Class 3 hitch and Warn Reciever shackle, Tuffy security box, Hella E-Codes 100/80W with custom harness, Hella 500 driving lights 100W bulbs, Optima Red Top and 160 Amp alternator, Rusty's tow hook's and brackets, JKS Gen II disconnects, Rusty's motor mounts, Rusty's transfercase skid, C4x4 double-tube rocker guards, HI LIFT
    Jeep Pics

  5. #5
    Registered John V.'s Avatar
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    Sep 1999
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    California, San Diego, USA.
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    Post

    I forgot to read the sig line . Just drive the XJ for a good 1/2 hour or so (day time no lights) then with the engine running see if the voltage settled down. I don't know about the XJ's but the ZJ charging system will ramp up the charging voltage when the air/battery is cold. John V.
    John V San Diego, Calif.
    Current wheeling videos

    Flop recovery at Gatekeeper Calico -- OUCH!
    http://www.youtube.com/watch?v=osy9XTY1N5A
    Anza Borrego Heart Attack Hill
    http://www.youtube.com/watch?v=_bScAe7rjsU
    Dusy Ersham Trail with 12 Hr tow out
    http://www.youtube.com/watch?v=NuIwv...e=user&search=

    Glow-in-the-dark Yellow Rubi LJ, Nth* 6" kit, Auto, 35's with 5:13's
    And when we have company in town and DD,
    ZJ with mostly home-made armor and 4.75" Franken-lift.

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