I put a new battery and alternator in my van and it ran fine all day. But the next day the battery was dead. I charged the battery and it worked. But why would my new battery go dead with my new alternator?
It is possible that you may have a large parasitic draw or the new battery was faulty. A parasitic draw test should be set up if the battery passes a load test. The alternator should also undergo a charging system test. A draw above 80 mA is generally considered excessive and the faulty circuit corrected. You may want to enlist the help of a mechanic, such as one from YourMechanic, who will have the equipment and expertise to diagnose the charging issue.
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