No power

So the problem I am having is with my grand am gt. One day I went to get gas and went to cut it on and had no power. It happened the day before also but I took the battery and had it charged and it started up. I took the battery and had it tested they said it was a good battery and was fully charged still but I still have no power. What else should I check? Could the battery be bad despite reading and testing good?

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Did they do a load test on the battery or just check voltage sitting?

Did they do a load test on the battery or just check voltage sitting?Just checked it sitting.

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Just checked it sitting.

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Then I would bet if you put a voltmeter on it while cranking, probably drops under 9 volts.
Most autopart stores will do a load test for free.

Then I would bet if you put a voltmeter on it while cranking, probably drops under 9 volts.

Most autopart stores will do a load test for free.None of the auto part stores here do load testing so I went and bought a new battery and at first when I hooked it up no power so I disconnected the negative cable and tried again and it worked. So I guess the old battery just had a dead cell I would assume. Thank you for telling me to load test the battery I was prepared to start testing any electrical component your way was much faster

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