Battery drain

Tiny
GREGG58
  • MEMBER
  • 1999 GMC SONOMA
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 156,000 MILES
My engine was tarting and runnin fine. 2 nites ago I shut it off and 20-30 minutes later the battery was completely dead. Next day I took the alternator to auto zone. They tested it 4 tines. The first was a fail. After that it was passed 3 times. Now my battery drains when off. Any ideas?
Tuesday, November 26th, 2019 AT 3:50 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

It could be a few things. However, I wonder why it failed the first time. There are diodes in the alternator that are to allow power to flow one direction. When bad, they allow power to flow back to ground and will kill a battery. So, that is in my mind.

Lets start with this. Here is a link that explains how to find an electrical draw. See if anything in it helps.

https://www.2carpros.com/articles/car-battery-dead-overnight

Let me know.

Joe
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Tuesday, November 26th, 2019 AT 7:49 PM
Tiny
GREGG58
  • MEMBER
  • 3 POSTS
Thanks for the link Joe.
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Wednesday, November 27th, 2019 AT 12:44 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
You are very welcome. Please let me know if it helps.

Take care and Happy Thanksgiving.

Joe
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Wednesday, November 27th, 2019 AT 7:52 PM
Tiny
GREGG58
  • MEMBER
  • 3 POSTS
It was my serpentine belt tensioner. Charged battery and it through the belt.
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Friday, December 6th, 2019 AT 3:24 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Great. I'm glad you found the problem. Let us know if you have questions in the future.

Take care,
Joe
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Friday, December 6th, 2019 AT 7:06 PM

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