2010 Prius Auxiliary Battery Drained Overnight

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Kendrick, Nov 9, 2013.

  1. Kendrick

    Kendrick New Member

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    I just bought a certified 2010 prius and have had it for 3 months now. Twice within one month, there was absolutely no power to start the car because the aux battery went dead overnight. I'm pretty sure I didn't leave any lights on and don't think I did anything differently when exiting the car for those 2 times. I took it into the dealership, and they couldn't find anything wrong. They said the battery was good. Does anyone have a clue what is draining the battery overnight? thanks
     
    #1 Kendrick, Nov 9, 2013
  2. jhinsc

    jhinsc Senior Member

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    Check if the aux battery is original to the car. You may need a new one.
     
    #2 jhinsc, Nov 9, 2013
  3. Former Member 68813

    Former Member 68813 Senior Member

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    Check if the light in the trunk/cabin is left on (most likely). In not, do parasitic current measurement and/or battery load test.
     
    #3 Former Member 68813, Nov 9, 2013
  4. spiderman

    spiderman wretched

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    it probably sat on the lot for a while and the battery is weak. i would just buy a good replacement and send the bill to the dealer
     
    #4 spiderman, Nov 9, 2013
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Check it with a digital multimeter. If you get voltage around 12.4~12.5 it's likely on it's way out. Higher, say 12.6 or more, it's ok. You can also try hooking up a lowish amperage intelligent charger, let it do it's thing. Then drive for a few days and then recheck voltage.

    Bottom line, if it's older than 4 years, and getting problematic, time for a new one.
     
    #5 Mendel Leisk, Nov 9, 2013
  6. terdog

    terdog New Member

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    I have a 2011 I had the same thing happen voltage dropped to 6.76 volts when trying to charge it I noticed it hanged up at 10.5 volts for awhile but then on went to a charge of 11.86. After I took charger off of it It disapaited at a rate of .01 every 15 seconds. It had a bad cell in it.

    Went with the Optima yellow top battery all is well
     
    #6 terdog, Dec 8, 2013
    ou812 likes this.
  7. Victor E. Sasson

    Victor E. Sasson Junior Member

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    I doubt the dealer would pay him anything.

    I believe the battery is warranted for 7 years, if it is a Toyota battery.
     
    #7 Victor E. Sasson, Sep 3, 2020
    Last edited by a moderator: Sep 4, 2020
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    Original manufacturer warranty is 8 years or 100,000 miles except in CARB states where it's 10 years or 150,000 miles for the hybrid battery only.

    The 12V auxiliary battery only originally comes with the bumper-to-bumper warranty. After that, I believe it's only a year at most.
     
    #8 Tideland Prius, Sep 4, 2020
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