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  1. #1
    GT Owner FBA's Avatar
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    Default 3rd Alternator, same results

    Changed my alternator as the original one was making some noise and voltage was irregular. I could see fluctuations in the lighting in the car, so figured it was time.

    We ordered an OEM unit and installed it, but it ended up at 14.8-15.3 volts charging. Ordered a rebuilt and installed that, only to find the exact same thing...

    I am told the ECU sets voltage output from the alternator...can anyone confirm and clue me in as to where the issue may be? Car runs fine, but shop is concerned about overcharging. The original alternator read the exact same voltage on my gauges.
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  2. #2
    GT Owner Xcentric's Avatar
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    Default

    Overcharging is >15.5 volts. Normal charging is 13-15 volts. If voltage drop between the alternator and the battery is >0.5 volts, you have a problem in the circuit. Otherwise, high charging rates can be caused by bad grounds (regulator/alternator to engine and/or battery to frame).
    Last edited by Xcentric; 10-28-2018 at 02:13 PM.
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  3. #3
    Blue/white 06' 2112's Avatar
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    Default

    Do we have the same alternator as the GT500?

  4. #4
    GT Owner FBA's Avatar
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    Default

    Quote Originally Posted by Xcentric View Post
    Overcharging is >15.5 volts. Normal charging is 13-15 volts. If voltage drop between the alternator and the battery is >0.5 volts, you have a problem in the circuit. Otherwise, high charging rates can be caused by bad grounds (regulator/alternator to engine and/or battery to frame).
    So at 15.3 volts, it is not overcharging?
    2019 Lamborghini Urus (inbound)
    2018
    Lamborghini Huracan Performante
    2017 Sierra Denali 2500 6.6
    2016 Corvette Z06
    2016 911 TTS /695 HP/ 800 TQ
    2005 White GT /850 WHP



  5. #5
    GT Owner PeteK's Avatar
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    That's too high. How are you measuring it? With a digital meter across the battery terminals or with the gauge on the dash? You must use an accurate gauge across the battery terminals. If that different from the gauge on the dash, start looking for a problem with the gauge or grounds.
    Pete K

    Cars are for driving--if you want art, get something you can hang on the wall!

  6. #6
    GT Owner FBA's Avatar
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    Multimeter across the battery...
    2019 Lamborghini Urus (inbound)
    2018
    Lamborghini Huracan Performante
    2017 Sierra Denali 2500 6.6
    2016 Corvette Z06
    2016 911 TTS /695 HP/ 800 TQ
    2005 White GT /850 WHP



  7. #7
    GT Owner PeteK's Avatar
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    Quote Originally Posted by FBA View Post
    Multimeter across the battery...
    Does the gauge agree with the multimeter?
    Pete K

    Cars are for driving--if you want art, get something you can hang on the wall!

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