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GT350 Voltage

fastd

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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?
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Tomster

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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.....
 

iamevan

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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?
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?
 

Demonic

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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.
 

JAJ

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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.
 

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iamevan

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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.
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.
 
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fastd

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

JAJ

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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.
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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