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Left Power On. 12V Died.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Aaron, May 20, 2013.

  1. Aaron

    Aaron Member

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    For the first time ever I accidentally forgot to push the Power button upon exiting my 2008 Prius. I came back to the car about 3-4 hours later to find it completely dead. The 12V is an Optima yellow top about a year old. Had to jump start it using my wife's car.

    Questions:

    1. Should this have happened to an Optima only a year old? I thought these were top tier batteries.

    2. Did I cause any damage to the 12V running it all the way down to dead?



    DROID RAZR ? 2
     
    #1 Aaron, May 20, 2013
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. I assume you had left the car IG-ON, where all instrument panel warning lights are on and the car is not READY. In that mode, there is a heavy drain on the 12V battery and regardless of whether the battery is in top condition or not, it will be dead after 3-4 hours.

    2. Yes, you did. You'll have to fully-charge the 12V battery now, then see if it will hold a charge or not. Plan to spend a whole day charging the battery. Don't think it will be fully-charged after one hour.
     
    #2 Patrick Wong, May 20, 2013
  3. Aaron

    Aaron Member

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    Thanks Patrick.

    I put it on a charger last night and it was fully charged by morning (green light on the charger). How can I tell if I caused damage?

    I do have a Scan Gauge II that can read voltage. Can I check battery health?

    DROID RAZR ? 2
     
    #3 Aaron, May 20, 2013
  4. Rich12

    Rich12 Member

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    #4 Rich12, May 20, 2013
  5. FuelMiser

    FuelMiser Senior Member

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    Just see if it holds a charge. Volts should remain 12.2 - 12.5 overnight.
     
    #5 FuelMiser, May 20, 2013
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    A fully-charged AGM battery should read 12.9V with no load applied, after you've waited overnight to let the surface charge dissipate.
     
    #6 Patrick Wong, May 20, 2013
  7. Aaron

    Aaron Member

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    What's the procedure to test with the Scan Gauge? I remember seeing it on this forum awhile ago, but can't find it.

    DROID RAZR ? 2
     
    #7 Aaron, May 20, 2013
  8. Scully

    Scully Junior Member

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    Where do I go to charge prius battery. Can someone jump me first or do I have to take battery out of car
     
    #8 Scully, Feb 27, 2020
  9. jerrymildred

    jerrymildred Senior Member

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    Are you at home? If so, just connect your charger and plug it in. If you don't have one, get one at an auto parts store or order from Amazon or something. Just be sure it's able to safely charge an AGM battery. I also recommend getting one that checks the polarity before applying power to the dead battery. Good protection from brain farts. ;)

    Someone could jump you, but if they connect the jumpers backward, it could cost you a couple thousand dollars to repair the damage. And you'd have to drive for several hours to get the battery back to full charge. Anyone who has a car really should have a battery charger.
     
    #9 jerrymildred, Feb 28, 2020
  10. sam spade 2

    sam spade 2 Senior Member

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    Any of the above, depending on your circumstances.
    No different that the 12 V battery in any other car.
     
    #10 sam spade 2, Feb 28, 2020
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