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Alternator Charging issue

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Old Dec 4, 2015, 05:16 AM
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Originally Posted by Biggiesacks
If your alternator is putting out that kind of voltage, then your battery shouldn't be dying. I would look into the connection between the alternator and the battery. Do a resistance test between the terminal on the alternator and the positive terminal on the battery, with all harnesses connected, and post the results.
Isn't it true that with these cars the alternator charges the battery to make sure its full or to a certain voltage but the alternator also feeds power to the ecu ect. while driving. The battery is just for start up and a few other electrical components such as radio ect.
Old Dec 4, 2015, 07:21 AM
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Originally Posted by Jeepyedo
Isn't it true that with these cars the alternator charges the battery to make sure its full or to a certain voltage but the alternator also feeds power to the ecu ect. while driving. The battery is just for start up and a few other electrical components such as radio ect.
This is true, but the alternator's connection to the vehicles electrical system is via the positive terminal on the battery. If it does not have a good path to the battery then it will also not have a good path to the rest of the electronics. When you measured the voltage from the alternator was that in the car at the positive battery terminal? Or was it on a test bench?
Old Dec 6, 2015, 08:18 AM
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Originally Posted by Biggiesacks
This is true, but the alternator's connection to the vehicles electrical system is via the positive terminal on the battery. If it does not have a good path to the battery then it will also not have a good path to the rest of the electronics. When you measured the voltage from the alternator was that in the car at the positive battery terminal? Or was it on a test bench?
The test was done while the car was running. The battery tested good since it was less than 1 week old before being drained after car initially died I put the battery on a charger and charged it all night. The following day took it into the shop to test both battery and alternator, tech insisted that the alternator is bad since its internally regulated and not charging correctly.
Also if I disconnect the positive terminal on the battery while the car is running will this kill the car or does the alternator provide power to keep the car running? A local guy suggested I try that.
Old Dec 6, 2015, 06:58 PM
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Originally Posted by Jeepyedo
The test was done while the car was running. The battery tested good since it was less than 1 week old before being drained after car initially died I put the battery on a charger and charged it all night. The following day took it into the shop to test both battery and alternator, tech insisted that the alternator is bad since its internally regulated and not charging correctly.
Also if I disconnect the positive terminal on the battery while the car is running will this kill the car or does the alternator provide power to keep the car running? A local guy suggested I try that.
do not do that, you can destroy your alternator. The alternator receives a signal from the ECU that controls the regulator. With your car running what voltage do you read between the positive and negative battery terminals? If you dont have a meter go pick up a cheap one, you really cannot even attempt to diagnose this without one.

Last edited by Biggiesacks; Dec 6, 2015 at 07:06 PM.
Old Dec 7, 2015, 05:18 AM
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I Think I got it. Replaced the alternator yesterday, and car has been running good. No battery lights on the dash or dimming of lights ect. I didn't charge my battery and knew it was low, actually read 11 volts. After the initial start up the motor ran at a higher rpm to charge the batter, I watched the amps go up on the battery terminal and then the car idled normal. Also went through and checked all the grounds. Thanks for the help everyone.
Old Dec 7, 2015, 08:36 AM
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Glad you found the problem. Had the same issue changed the alternator and everything was good.
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