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Battery drain?

Tiny
FARMERPARSON
  • MEMBER
  • 2005 BUICK LESABRE
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
The battery and alternator has been replaced. Their is a parasitic drain that I have found at the PCM (battery fuse under hood). With a well charged battery I can start the car and place voltmeter on alternator and watch the voltage drop drastically. I have had the new alternator (not refurbished) checked and it checks out fine. Any suggestions?
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Friday, November 29th, 2019 AT 4:04 PM

8 Replies

Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

Here is a diagnostic troubleshooting guide on how to find a parasitic draw in an automotive circuit so that you can fix it, in the diagrams down below. You will need to use a Digital Multi-meter [DMM] to use this guide. here is a guide explaining how to use one below, if needed:

This guide should help

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

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Please go through these guides and get back to us with what you discover.

Thanks,
Alex
2CarPros
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Friday, November 29th, 2019 AT 5:07 PM
Tiny
BRIANDEB67
  • MEMBER
  • 1 POST
  • 2001 BUICK LESABRE
  • 6 CYL
  • 201,000 MILES
I have a 2001 buick lesabre custom. The car suddenly died and would not restart. The battery was dead. Bosted it and it restarted only to die again. The next day I tried to boost it again with no luck. A day later I was able to boost it from under the back seat. Drove it home and let it run awhile. All lights worked and were bright. Turned car off after awhile. It was completely dead. The next day it showed les than 4 volts.
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Thursday, August 6th, 2020 AT 10:38 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
You have a short circuit somewhere or something is still On that's draining the battery overnite-
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Thursday, August 6th, 2020 AT 10:38 AM (Merged)
Tiny
DAVE'S BIG BACKYARD!
  • MECHANIC
  • 262 POSTS
It might just need a batt.
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Thursday, August 6th, 2020 AT 10:38 AM (Merged)
Tiny
MIKEW22
  • MEMBER
  • 1 POST
  • BUICK LESABRE
2001 Buick laSabre 57,000, 3800 V6 engine. The battery is good, alternator is good (14.5V while running). Battery holds charge at 12.5V. The battery will drain down overnight with no apperant reason. Any idea where to start?
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Thursday, August 6th, 2020 AT 10:38 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
How old is the battery?

Could be a case drain or ( an excessive parasitic drain ) meaning could be a short in the electrical system other than eletronics memory.
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Thursday, August 6th, 2020 AT 10:38 AM (Merged)
Tiny
JULES407
  • MEMBER
  • 1 POST
  • 1998 BUICK LESABRE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 56,000 MILES
If I let my car sit for 3-5 days without using it, the battery goes dead. I have had 2 new batterys in about 2 yrs. If start the car daily or drive it every couple of days I have no problems. I had the car check for electrical problems but they told me everything was ok. My question is, is it ok to put a battery charger on over night even though the car still starts?
Thank you
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Thursday, August 6th, 2020 AT 10:38 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Hi there,

Yes you can do that, but what I would do is get a current draw test done, and make sure that the alternator is checked as a potential current draw via a faulty diode, your mechanic should be able to do this, let me know if they don't.

Mark (mhpautos)
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Thursday, August 6th, 2020 AT 10:38 AM (Merged)

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