If you're saying the battery dies after the car is cranked and running, its possibly a bad connections somewhere but most likely you alternator. Check your alternator fuse (if it has one), and check your connections on your alternator. Check and clean the battery terminal connectors too if you can. And lastly, make sure your alternator belt has a good tension on it. Inspect your alternator belt for cranks or worn grooves. Check your battery with a volt meter hooked up, it should read roughly 12.4V and 12.7V. While the volt meter is hooked up, have a friend crank the car while you look at the volt meter. If it slowly drops that means your alternator is bad. Its not charging/maintaining your battery. NEXT, pull your alternator off and take it to the autoparts store to verify your alternator is TRULY THE CULPRIT OF THE SYMPTOM. Make sure its putting out the correct voltage and is working. If not replace the alternator.

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