Shuts off while driving after replacing the battery and alternator

KALE LAWRENCE

MEMBER
1994 MERCURY COUGAR
3.8L
V6
2WD
AUTOMATIC
89,544 MILES

I put in a new battery and new alternator but when I start the car it drives for 10 minutes and then it shuts off. Then if I jump the battery, it goes down the block and shuts off again. Sometimes it will just work the right way but if I let set for an hour it starts that again. It would go from 14 v and goes all the way down to the red. Please help

4 Replies

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

When you say it goes from 14v into the red, is that with the engine running? After 10 minutes, is the battery dead?

Do me a favor. I need you to check something. It sounds like the alternator isn't working properly. I need you to check power at the battery with it running to determine if the alternator is the issue or if there is a short.

Here is a link that shows how it's done:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Do this and let me know the results. Also, when you start it and it stalls, feel the battery cables to see if they are hot.

Take care,

Joe

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Thursday, February 17th, 2022 AT 4:43 PM

KALE LAWRENCE

MEMBER
5 POSTS

It was the alternator it was bad and I got my money back. Thank you everyone.

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Friday, February 18th, 2022 AT 9:12 AM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

Thanks for the update. I'm glad to hear you got it fixed. Based on your description, it sounded like the alternator was the issue.

Regardless, please feel free to come back anytime in the future if you have questions. You are always welcome.

Take care,

Joe

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Friday, February 18th, 2022 AT 3:20 PM

KALE LAWRENCE