Correct voltate for 12v battery?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by f18cmech, Nov 21, 2018.

  1. f18cmech

    f18cmech Junior Member

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    Hi all,
    I think my 12v battery maybe on its way out, the keyless system no longer works and I'm readint 12.45 volts with a volt meter with the car off. Would you say this means this battery could stand to be changed? Thanks.
     
    #1 f18cmech, Nov 21, 2018
  2. audiodave

    audiodave Active Member

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    That's not a terrible voltage. Turn the headlights on and see what it reads.
    Change battery in your key?

    Posted via the PriusChat mobile app.
     
    #2 audiodave, Nov 21, 2018
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    I think I've gotta stay away from battery threads.
     
    #3 Mendel Leisk, Nov 21, 2018
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  4. f18cmech

    f18cmech Junior Member

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    Yes, key battery changed, and it worked sporadically for a couple days but now it hardly works at all. When I go into diag mode, not in ready mode, it says 11.9, drops and holds at 11.4 with lights on, goes back to 11.9 when off. However a battery test showed it only had 150 CCA out of the 325, and read 12.45 volts.
     
    #4 f18cmech, Nov 21, 2018
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  5. f18cmech

    f18cmech Junior Member

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    Why?
     
    #5 f18cmech, Nov 21, 2018
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    They're addictive, lol. That CCA is bad, think it's the clincher: time for a new one.
     
    #6 Mendel Leisk, Nov 21, 2018
  7. audiodave

    audiodave Active Member

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    #7 audiodave, Nov 21, 2018
  8. 05PreeUs

    05PreeUs Senior Member

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    D.O.A.
     
    #8 05PreeUs, Nov 22, 2018
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  9. sam spade 2

    sam spade 2 Senior Member

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    The additional readings that you provided definitely indicate a 12 V battery on the way OUT.
    Time for a replacement.

    You also need to manually check the voltage while the car is ON, in READY mode, to be sure it is charging properly.
     
    #9 sam spade 2, Nov 22, 2018
  10. bisco

    bisco cookie crumbler

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    how old is it? that's one of the few times low cca has been reported here
     
    #10 bisco, Nov 22, 2018
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  11. f18cmech

    f18cmech Junior Member

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    It was changed at 98k and now the car has 222k. Far more than was changed the first time. But, the alarm seems to work when it wants. Not sure why, but sometimes will work when battery is at 12.1 but other times not. I'm thinking its not the battery, unless low voltage will result in the alarm working intermittently. Any thoughts?
     
    #11 f18cmech, Nov 29, 2018
  12. TMR-JWAP

    TMR-JWAP Senior Member

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    A new 325cca Prius 12v battery will usually test at 425ish.

    You're heading toward being broken down somewhere due to a failed 12v battery. Regardless of your problem, you need to replace it. Odds are reasonable, after fixing the obvious, the other problem will probably resolve itself.
     
    #12 TMR-JWAP, Nov 29, 2018
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  13. sam spade 2

    sam spade 2 Senior Member

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    Yes it will.
    You should be focusing on finding out why the battery reads 12.1.
    It should NEVER be that low.

    Odds are that the battery is just getting weak.
     
    #13 sam spade 2, Nov 30, 2018
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