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Discussion Starter · #1 ·
Hello everyone not too long ago I purchased a 2010 Chevy cobalt LT. I noticed the voltage while driving drops to 12.5v. When the car is started it has 14.2 but once it gets above 80* outside temp or when the engine reaches operating temp it rapidly falls to ~12.5. Last month it refused to start and i replaced the battery but the problem remained. I then replaced the Alternator but the problem is still apparent. I have taken it to the Auto parts store and had testing done on both new parts while inside the car but it all checks out good. Any ideas?
 

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Going down to 12.5 at idle is normal, the alternator is not turning fast enough to produce the necessary voltage or current needed so it switches off. What is your idle RPM, it should be at least 750-800.
 

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Then you have a problem, broken or bad connection if everything is new. Should be at 14.3 when at highway speed.
 

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Well it should drop^after the battery is fully charged but maybe not to 12.5.
 

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Discussion Starter · #7 ·
i understand that, I'm more wondering if i should start by checking alternator connections and fusible linkages or if i should begin near the fuse box looking at relays that warm up
 

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Check the charge of your battery if it is fully charged you may not have a problem.
 
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