I have been having trouble starting my car (needed to jump it twice, once in the morning, and once in the afternoon). Sometimes it would make a clicking noise when trying to start or it would be silent. Using a multimeter I checked the following voltages on the battery:

Car Running: 13.5 Car Off: 12.5

I disconnected the battery overnight to see if there was a drain, but the car still wouldn't start the next morning. I checked the voltage and it started at 11.3 and creeped up to 11.5 as I left the multimeter connected.

Any idea what could be wrong? Is it a bad battery? The car is a 2008 Pontiac G6 and the battery was purchased in 2011.

3 Answers 3


The battery is bad. You need to get a replacement ... the one you bought may still be under warranty, though probably pro-rated at this point. More than likely, your current battery has a bad cell in it which doesn't accept the charge it is supposed to. Since batteries are built with multiple cells configured to work in series, one cell is all it takes to make the whole thing bad.

  • 1
    Might it not be a short instead? I would hate to replace the battery and have the same problem
    – easycheese
    Feb 19, 2014 at 15:55
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    @easycheese ... If you are disconnecting the battery, there would be no drain on it. It should not incur any degradation of voltage disconnected, especially if the time period is just overnight. I don't blame you for not wanting to replace it, but with the information you have provided, it leads directly to a bad battery. You can always take it down to the parts store and have it load tested to find out prior to purchasing a new one. Feb 19, 2014 at 16:35
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    You should also bring the bad battery with you as they might have a core charge rebate (bring dead battery and get a discount). They'll definitely recycle bad battery for you.
    – Bob Cross
    Feb 19, 2014 at 16:42
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    Took it to Advance Auto and they confirmed the bad battery after a charge. I also had the original receipt so it was a free replacement (3 year warranty). Thanks!
    – easycheese
    Feb 19, 2014 at 21:06
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    I would also check the running voltage again with the new battery. You should see about 14 volts.
    – mikes
    Feb 20, 2014 at 1:14

Check, tighten and clean the main ground coming from the battery. It will be attached to the frame somewhere. You should see a spark.


Is the top of the battery clean? Dirt and grease combined with moisture are conductive. That in itself could be a source of parasitic power leakage. As a result draining the battery as a result. I read further in your post that the battery is 5 years old...I agree with Paulster2 that the battery is probably toast.

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