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Charging system, battery drains overnight?

Tiny
ROPAR47
  • MEMBER
  • 2004 KIA RIO
  • 1.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
Charge battery. The car starts and runs fine. Alternator putting out over 14 volts. Everything seems normal. Park the car overnight and the battery will be so drained that it won't power the dome light. Old alternator stopped working. Putting out zero. Installed Auto Zone rebuilt one. Now this problem. Did I just get a bad rebuild?
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Wednesday, May 24th, 2023 AT 9:56 AM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

It is very possible that you got a faulty one. There are diodes that are designed to only allow power to travel in one direction. If they are bad, it will drain the battery,

Do this. Charge the battery and remove the 80amp main fuse to the alternator overnight. In the morning, reinstall the fuse and see if the battery is dead.

Also, you could disconnect the alternator. If you do, note that power is direct to the alternator at all times, so don't let anything short. The fuse would just be easier. LOL

I attached the charging system electrical circuit schematic so that you have a reference. See pics 1 and 2. Pic 3 shows the fuse in the under-hood fuse box to remove.

Let me know what you find.

Take care,

Joe

See pics below.
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Wednesday, May 24th, 2023 AT 9:10 PM
Tiny
ROPAR47
  • MEMBER
  • 2 POSTS
The reconditioned part had bad diode. Took it back. The new one works great. Still had to do the work twice. Huge pain on 04 Rio. Has to come out the bottom. Remove tie rod, etc. Etc. Thank you for your prompt reply.
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Friday, May 26th, 2023 AT 3:32 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

They are difficult. LOL But I'm glad to know it's working properly now. I had a feeling that was the cause.

Regardless, take care of yourself, and feel free to come back anytime in the future.

Joe
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Friday, May 26th, 2023 AT 9:52 PM

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