You're describing a defective battery, but it is also possible for the charging system to be developing exactly one third of its maximum capacity. That can be enough at times to keep the engine running while having not enough extra capacity to recharge the battery after starting. Here's links to some related articles:
https://www.2carpros.com/articles/how-a-car-battery-works
https://www.2carpros.com/articles/car-battery-load-test
https://www.2carpros.com/articles/how-to-replace-a-car-battery
https://www.2carpros.com/articles/how-to-check-a-car-alternator
The last one shows how to start the charging system test on your own, but if this turns out okay, it only means it is okay to continue on with the rest of the tests. That requires a professional charging system tester. I can describe that in more detail if it comes to that. Most places that sell replacement batteries can test your old one first, and just about all independent repair shops can complete the tests on the charging system.
Let me know if this helps or if you need more information.
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Sunday, June 12th, 2022 AT 11:54 AM
