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“Good” 12v reading in mdf?

Discussion in 'Gen 2 Prius Main Forum' started by CanTG, Jan 18, 2020.

  1. CanTG

    CanTG Junior Member

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    What is an appropriate 12v reading (on the mdf, in the “display” menu)? Mine is reading 12v according to that display menus - is it time for a new 12v battery?
     
  2. CanTG

    CanTG Junior Member

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  3. edthefox5

    edthefox5 Senior Member

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    12 volt is not good but tells me very little about the true condition of the battery, will it provide power under load?

    You can do a simple load test at homebut it requires a voltmeter,
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Hard to say. The Multi Function Display reading, with the car "woken up", is not that useful.

    Check it with a volt meter, with the car off, for a better idea. If possible, pop the hood the night before, then first thing in the morning check at the under-the-hood jump start point. This will get the battery at it's most "honest" time, and having the hood pre-popped avoids the small drain from opening a door.

    For an even better idea, get it tested with an electronic load tester. Most battery retailers have them and will test for free. Or you can DIY with something like Solar BA9.

    How old is it btw?

     
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Neglected to mention, with the independent volt meter measurement, 12.6~12.9 is good, 12.4~12.5 is meh, lower, not so good.
     
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  6. bisco

    bisco cookie crumbler

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    how old is it?
     
  7. CanTG

    CanTG Junior Member

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    As this is “new to us” (2006 with 127,000 miles), I’m unsure of the age of the 12v - also, I’m in Canada so concerting kms to miles!
     
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  8. psusi

    psusi Junior Member

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    Turn on the headlights. If the voltage drops below 11, it's time for a new battery. Well, if it goes to like 10.9 for a second, then comes back up, it may be ok, but if it keeps going down, it's not. If it gets to 10.5, shut it down or the computer will crap out in a second.