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Thread: Battery draw down

  1. #1
    Z8 Novice
    Join Date
    Nov 2018

    Battery draw down

    If I do not drive my car for 5 days the battery goes dead. Had it checked by Interstate and it is a good battery. Seems like I must have something drawing it down. Any ideas of how to diagnose?

  2. #2
    Are you locking the car with the key to activate the car alarm? That will deplete the battery over time. Others on the forum have reported that leaving the flashlight in the holder will also draw down the battery. If you don’t know the history of the battery, I would replace it too.
    My Best,


    2002 Z8 Jet Black//Sport Red
    2012 SLS AMG Obsidian Black/Classic Red

  3. #3
    Ed - I thought locking actually puts the Z8 to a “sleep mode” and reduces the power consumption saving the battery power. I always lock mine when parked in the garage.
    Last edited by Musta10000; March 5th 2019 at 02:50. Reason: Typos
    Skip Hammerman

    2002 BMW Z8 - Meisterschaft GT, PP installed, CDV delete. 100,000 Mile Club
    2013 BMW X3
    2015 Porsche 911 Targa 4S

  4. #4
    Team Z8 Satch's Avatar
    Join Date
    Sep 2014
    Well, huh! I learn something new every time I come on here! For what it's worth, I continue to use Optima battery maintainers on the Z8s because they provide information, not just a red/green LED (but that's only in the rental garage; here at Mondo Condo, my Z4 lives with a Deltran battery tender). I have never had a BMW that didn't have at least some battery drain, and letting a battery sit when it's drawn down will kill it right quick-like.

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