GT350 Voltage

Discussion in 'Shelby GT350 Mustang' started by fastd, Sep 23, 2017.

  1. fastd

    fastd Member

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    I have a 2017 GT350...noticing that the voltmeter often reads in the 12's. At a stop light was just 12.2; sometimes gets up to 14 but most often 12.7-13.1.

    I called Ford service and the tech was trying to make it sound like this is OK but doesn't seem right...anyone have similar voltmeter readings?
     
  2. Tomster

    Tomster Beware of idiots

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    Its fine. The system voltage is regulated to only charge the battery when it is low. Let it sit for a couple weeks and then see what the system voltage is then.....
     
  3. iamevan

    iamevan Member

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    I’ve noticed the same thing. I don’t think it was acting this way before. Did you ever find out if it’s normal?
     
  4. Demonic

    Demonic Well-Known Member

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    Admittedly I can’t speak specifically to the Shelby, but this is often just a function of how alternators are set up in general. As the alternator spins faster the output will be higher but is going through a voltage regulator that limits the voltage to say 14 V for example. When the battery is pretty much topped off, the voltage reading will effectively be reading the output of the alternator.
     
  5. JAJ

    JAJ Well-Known Member

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    Your 2017 GT350 has a "smart" alternator and a "smart" battery. Normal voltage is 12.9 V and it scales up and down between 12.8 at 150F and 14.2 at 20F based on temperature.

    This is from the alternator calibration for a 2016 GT350.
     
  6. iamevan

    iamevan Member

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    Where did you find this information? Temperature of the battery?

    In the morning before a cold start my gauge cluster voltage reading sometimes reads as low as 11.3v. I use a multimeter on the battery and it reads 12.4-12.6v.
     
  7. OP
    OP
    fastd

    fastd Member

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    not sure if its normal but hasnt been an issue so im goong with it.
     
  8. JAJ

    JAJ Well-Known Member

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    I have SCT's pro tuning software for the GT350 and it has the calibration tables for the alternator in it. The values I quoted were "nominal". The main purpose of this part of the alternator calibration is to adjust idle speed to compensate if the voltage gets too low. The table I looked at isn't clear on whether the temperature is the battery temperature or not.
     
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