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George H.
George H., ASE Certified Technician
Category: Chevy
Satisfied Customers: 18311
Experience:  GM Tech ASE Master Tech 15+ years
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I have 07 tb, have noticed that the voltage at the

Customer Question

I have 07 tb, have noticed that the voltage at the cirgarette sometimes close 13vdc. At times the voltage drops below 13 and stays there. Everytime I move the sarvc for a day or so it works fine. Have checked all the ground connections,they are all snug. There is one missing, the alternator ground. Should this be corrected or am I overlooking something simple?????
Submitted: 2 months ago.
Category: Chevy
Expert:  George H. replied 2 months ago.

Hello I will help you with your question,

It is normal for the charging voltage to fluctuate as different loads are applied to the electrical system.

Do you have a picture of the ground you think is missing?

Have you had the battery load tested?

Customer: replied 2 months ago.
the system has the ac running plus headlights and a fan.No . There is no ground between the alternator and the battery!!!
Customer: replied 2 months ago.
the battery has been load tested at Advanced Auto Parts , results looked good.
Expert:  George H. replied 2 months ago.

You say a ground is missing? Is that what you mean is you think there should be a wire between the alternator and the battery for ground? The ground path is the metal of the alternator case through the engine to the ground cable that is attached to the engine block.

The electrical system is constantly changing load so the regulator for the alternator changes the output voltage with the load. It is normal for anywhere from 15.5 volts down to 12.6 volts at the output of the alternator. It will reduce voltage to let the alternator spin freely saving fuel when the load is low.

It sounds like your system is operating normally, what is your concern with what you are seeing?