What causes a alternator to over charge?

Discussion in 'Troubleshooting & Diagnosis' started by throttle73, Jun 27, 2004.

  1. throttle73

    throttle73 Veteran Member

    Aug 18, 2002
    I think my alternator is overcharging and i was told it could be my ground or something wrong with the regulator. It's internal regulated and is fairly new. How should i go about checking my grounds?
  2. BlueZ/28

    BlueZ/28 Veteran Member

    Jul 21, 2004
    Grapevine , Texas
    The first thing you need to determine is voltage at the battery with the car running.(should be between 13 and 15 volts).
  3. Eric

    Eric Veteran Member Lifetime Gold Member

    I agree with Blue- just get a voltmeter and hook it up to the battery posts with the engine running and see what's what. 13.5-14.4 Volts is ok- anything higher and the voltage regulator inside the alternator is defective. A bad ground shouldn't overcharge a battery- but if you want to verify condition of alternator and put this out of the way for the test- hook a jumper cable from neg battery terminal to alternator mount or alt. casing and then do the voltage test.
  4. wayner

    wayner Veteran Member

    Check what those guys mentioned, but also a battery with defective cells could also appear as an over charged battery. The defective cell will reduce battrey voltage, the regulator could interpret that as an undercharged battery and ramp up charging amperage to compensate, there by overcharging the remaining cells. A good load test on the battery will usually indicate this, bit sometimes battery problems and shorts in cells can be intermittant.

    70 Camaro Z/28 with 461cu.in. BBC & OD Auto, 3.31 12 bolt posi.

    [This message has been edited by wayner (edited June 28, 2004).]
  5. archemedes

    archemedes Veteran Member

    Jul 17, 2002
    Saraland AL,USA
    if you have the charging system tested at auto zone (it's free) they can tell you if it's battery or alternator or neither (just because an electrical part is new doesn't mean it's good)

    To err is human; but to really screw things up
    requires a computer.

    Give blood play hockey!

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