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Q: Loosing power

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I just replaced the battery and starter I had to jump it to start I let it run for about hours turned it off it still wouldn't start back up unless I jump it once it on the lights go deam some time

My car has 136000 miles.
My car has an automatic transmission.

A: There a few things that could be happening ...

There a few things that could be happening here. Number one, you could have a draw that is draining the battery. If this is the case, you will need to do a draw test that is done with an amp meter. Most multimeters can handle up to ten amps. Usually that is sufficient to test for a draw. Of course, you will need to understand and have access to the correct tools to do this.

If you have a drain on the battery, charging it for a few hours at idle with the alternator is often no sufficient. Alternators don't charge efficiently at idle and they are not designed to charge batteries anyhow. They are designed to maintain the electrical system of your car only. Charging a dead battery is a different process. Doing a specific gravity test on your battery is the only accurate way to know its state of charge. A load test tests the batteries ability to produce the necessary current to start your motor.

What I think is going on, if I am interpreting your description correctly, is you have a bad connection in the starting system. Your starter requires much more current to work than every other system in your car. So if connections aren't up to par, it won't work. Keep in mind, what looks like a good connection to our eye, does not mean electricity agrees. A jump start could add just enough voltage to the system to overcome the poor connection.

Which one of these is the case will require some diagnosis. I recommend the following inspection to help you out; Car is not starting inspection which can be performed by a certified technician from YourMechanic at your home or office.

Good luck!

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