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2013 ATS, 1993 ETC
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32 Posts
Discussion Starter #1
My 2013 3.6 Ats performance Is showing a charge voltage of 15 volts. The battery is seven years old, but after sitting all night, It still shows 12.27 volts!
I wonder if the voltage regulator is bad or is the battery at fault. It starts strong and the lights are bright with the key off. I think it should show a charge just over 13 volts. What does the forum suggest??
 

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2004 CTS Lux Sport and 2014 ATS 2.0T AWD Lux
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953 Posts
If your battery is 7 years old and original in car, I would get the battery tested and be ready to replace it before winter (are you in the north?). The battery in the ATS is really buried, so it's probably best to have a shop do it.
 

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2014 ATS 3.6 Premium RWD, 2016 Corvette Z06, 2018 GMC Sierra Denali 2500HD Diesel
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2,867 Posts
Charging voltage will vary depending upon state of charge, system load, driving conditions, etc. The ECM controls charging profile to provide increased fuel economy and to improve battery life so it is absolutely normal to see the system voltage vary a lot while driving.

Is it staying at 15 volts all of the time while driving? If so the battery is likely just about gone, the high voltage is indicative of the alternator being set to a high charge rate and if it stays there then the battery is not accepting/retaining a charge. GM tends to buffer most readouts so your voltage display in the car won't follow in real time but the alternator output is briefly dropped to zero current to sample battery voltage and based upon the system voltage during these brief sample periods the ECM will determine whether the battery is still largely discharged and it will appear to stay at high voltage. The higher the voltage on the nominal 12 volt bus, the higher the battery charge rate. System voltage will go briefly high intermittently with a fully charged battery because of the light load on the alternator but it won't be kept at this voltage for a sustained period of time with a good battery that is fully or near fully charged.

No load voltage really doesn't tell you anything about battery condition however if it is sitting at 12.27 no load then it is well under its normal voltage which is in the 12.8 volt range no load for an AGM type battery. See how much the voltage drops with the headlights on (engine off).

A failing battery is also very hard on the alternator which is rated for the current it can deliver at a low duty cycle while a depleted battery forces it to maintain a higher than typical duty cycle.
Or in short, after 7 years your battery is probably "toast". :)

Rodger
 

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2013 Luxury ATS 2.0T Manual
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863 Posts
I'd proactively replace it if you have any question at this point. If you got 7 years out of this one, it's reasonable to expect at least another 5 from a replacement. With these types of lifecycles and the typical life expectancy of a modern car, I don't think you're saving yourself a battery replacement in the long run by waiting to replace it until you absolutely have to (unless you're planning on dumping it within the next year). And, like rsingl mentioned, you may be damaging a more expensive part just so that you don't have to replace another that will need to be replaced soon anyways.
 

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2013 ATS 3.6L AWD Performance
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66 Posts
At 7 years, id say youre due for one.

i have the same year, trim, engine etc and mine went somewhere in the winter of 2017-18.
 

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2013 ATS, 1993 ETC
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32 Posts
Discussion Starter #8
My 2013 Ats 3.6 performance. Got the new battery for $423.19 Bucks. I am still seeing a charge voltage of 15.1 to 15.2 volts! It stays that high jumping between 14.9 and 15.2.
 
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