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Battery is dying

my will start(put in new battery) but will not charge up. When disconnect the neg side of battery the car dies. What is wrong??

You don’t state the year of your Sunfire. But removing a battery terminal from the battery while the ignition switch is in the run position or while the engine is running can damage computers and modules from current spikes. And if your Sunfire has the voltage regulator as part of the computer, you might have damaged the computer from removing the battery cable while the engine was running.

Tester

Tester beat me to it.

it is a 2002. you dont think the altenater is bad??

Assuming you are lucky and you did not do the damage Tester listed, and if you can get it started and to an auto parts store, most will test your battery and changing system for free. Right now you don’t know if the battery is a problem or if your charging system has a problem .

thanks for your help