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2010 CTS Wagon
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214 Posts
Discussion Starter #1
I am seeing 15V on the DIC after start up, with it settling to 14.6-14.8. Now it has been sitting for a long while (approximately 3 weeks) and only driven it about 20 miles in the last 3-4 weeks (its a long story). Is this normal? As I recall, I would see 13.8-14.1 when driving, but I never really paid attention to it. With all the repairs on the cars, I am probably being overly sensitive to every creak/warning/signal as a sign of impending doom. Having issues trusting the car at this point.
 

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2011 CTS-4, Sedan,Tuscan Bronze
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388 Posts
Off hand I don't believe there is a problem. If you want to make sure you're getting an accurate reading use a good DC voltmeter. Hook up the + lead to
the + post of the battery and the - lead to the - post.
 

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2001 SLS & 2012 CTS
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57 Posts
I don't think the reading is accurate.

Mine shows around 15 sometimes & as low as 12.5 sometime. It is basically a worthless reading in my opinion.
It was enough to make me check it as any good charging system should be in the 13.5-14.5 range anytime the car is running.
 

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2008 CTS
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213 Posts
Voltage from 15 to 12.5 is normal. Usually on the high end cold and low in the heat. Modern cars have a more sophisticated regulating system than the cars of 15 years ago. The regulator is no longer built into the alternator but is regulated by the body computer that is better able to deduce the load placed on the electrical system. If the car has been sitting for a while, the battery is somewhat discharged and the alternator is trying to charge it quickly. Hence the high voltage immediately after start up.
 

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'14 CTS-V LongRoof; '16 ATS-V Sedan,' 04 Trailblazer 4x4; '10 CTS LongRoof gone but never forgotten
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14,143 Posts
I agree. I have seen mine fluctuate during driving and all seem normal over 85000 miles. I am of the opinion that you have nothing to be concerned about.
 

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2001 SLS & 2012 CTS
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57 Posts
Actually a fully charged 12v battery should put out 13.2v. A reading of 12.5 should not be a normal occurrence.
Mine showed this after a 30mile ride, causing me to check mine.

I measured mine with a calibrated Fluke meter & I'm not impressed with the accuracy of the DIC display.
 

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SOLD - 2010 CTS4 Premium Wagon-Diamond White-Cashmere Interior
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2,930 Posts
The only way to get an accurate OCV (open circuit voltage) reading is to remove both cables from the battery and check it with a multimeter. Using the DIC or the battery (when installed in the car) posts or the remote jump start posts will not give you an accurate reading. I believe that the OP has nothing to worry about with his readings. Is it your original battery? If so, you might want to shop before it eventually fails you.

Marv
 
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