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Battery toast?

Discussion in 'Gen 3 Prius Main Forum' started by Johnny Cakes, Feb 8, 2018.

  1. Johnny Cakes

    Johnny Cakes Senior Member

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    My daughter is using the Prius this semester. Apparently she must have left something on because she said the car was so dead that even the doors would not unlock with the remote and she had to manually unlock the door. Once inside, there were no lights at all and, obviously, no response from pressing Start.

    I've only been following this forum for about a year but I seem to recall threads that indicate that since the Prius 12v battery is so small, once it is completely discharged it suffers great damage. Do I remember that right?

    If it takes purchasing a new battery, I'd rather do that than possibly leave her in harms way with a weak battery doesn't hold a charge well in the future.

    All opinions appreciated! Thanks!
     
    #1 Johnny Cakes, Feb 8, 2018
  2. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    The AGM battery in the Prius does not like to be deeply discharged. It is probably easiest to replace it for best reliability. You may be abke to recharge the old one but it will likely cause issues again.
     
    #2 Prodigyplace, Feb 8, 2018
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  3. Raytheeagle

    Raytheeagle Senior Member

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    I’d get a new battery;).

    One option would be to keep the battery and forgo the core charge and put it on a charger to see if you get more life out of it :).

    Then I’d investigate the daughters mistake to get at the root of the replacement :whistle:.

    It will lead to the best piece of mind(y).
     
    #3 Raytheeagle, Feb 8, 2018
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  4. Johnny Cakes

    Johnny Cakes Senior Member

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    Thanks -- the daughter's mistake was to leave a dome light on. She did the same thing in my wife's car several months ago. :(

    I used Facetime to show her how to correctly jump the car, which was successful. I'll replace the battery when I next visit her. In the meantime, I had her leave the car in READY mode so that the 12v battery can be charged.

    Any suggestions on the number of hours for that?
     
    #4 Johnny Cakes, Feb 11, 2018
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  5. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    I believe some have done that for 7 hours.

    EDIT: RayTheEagle is more knowledgeable on this.
     
    #5 Prodigyplace, Feb 11, 2018
    Last edited: Feb 11, 2018
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  6. Raytheeagle

    Raytheeagle Senior Member

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    I would say an hour should be sufficient, but that depends on many situationally specific factors :(.

    The longer the better though(y).
     
    #6 Raytheeagle, Feb 11, 2018
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  7. padroo

    padroo Senior Member

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    #7 padroo, Feb 11, 2018
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  8. Johnny Cakes

    Johnny Cakes Senior Member

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    Thanks for the quick reply guys! She's actually going out today so by the time she gets back it will be about seven hours. Sounds like that should be plenty.
     
    #8 Johnny Cakes, Feb 11, 2018
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  9. padroo

    padroo Senior Member

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    It the battery isn't charged up in seven hours I would say something is wrong. lol
     
    #9 padroo, Feb 11, 2018
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  10. Magnetic Me

    Magnetic Me Junior Member

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    The original battery in my Prius became fully discharged. It was never the same after that.

    I was fortunate to find a post on this forum showing how to install a larger Group 25 AGM battery.

    It isn’t a difficult job, and you don’t need any specialized technical knowledge.

    Replace OEM 12V battery with Group 25 AGM | PriusChat

    I’ve just added a few notes to that thread.
     
    #10 Magnetic Me, Feb 12, 2018
  11. Alicea Bowker

    Alicea Bowker Junior Member

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    I have left the power on for several hours by accident and when I came back to the car my battery was still almost full, so there may be a more in-depth problem
     
    #11 Alicea Bowker, Feb 12, 2018
  12. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    If you left the car in READY mode, it would charge the battery and turn on the engine if needed.
     
    #12 Prodigyplace, Feb 12, 2018
  13. Johnny Cakes

    Johnny Cakes Senior Member

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    Good post
     
    #13 Johnny Cakes, Feb 12, 2018
    Last edited: Feb 12, 2018
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