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Do I need a new 12V battery?

Discussion in 'Gen 2 Prius Technical Discussion' started by Starcheckered, Aug 11, 2011.

  1. Starcheckered

    Starcheckered Junior Member

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    In the thread for fuel economy is a link to checking your 12V battery (won't let me post a link yet because I'm new). I used these instructions and this is what I got:

    (Car had been off for 10 hours)

    IG off: Battery 12.0
    IG on: 11.6
    Car on:  14.0

    Is 11.6 low enough to need replacing? My mpg is seriously low (~20 mpg on my normal 45+ mpg commute) and I was referred to test it in another post which is why I checked.
     
    #1 Starcheckered, Aug 11, 2011
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Yes, I would change it. If you prefer to wait for symptoms, (beyond not getting good gas mileage) I would order a Optima Yellowtop from elearnaid.com now, so you have a battery when it shows a symptom and does not start. Otherwise, when it does not start, you will pay whatever the dealership feels like charging.
     
    #2 JimboPalmer, Aug 11, 2011
  3. Starcheckered

    Starcheckered Junior Member

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    Okay thank you very much! I figured that it needed replacing but wasn't sure how much below 12.0 is bad.

    The dealer needed the order the part today and I'm going on a road trip tomorrow so it cannot wait.

    Thanks again!
     
    #3 Starcheckered, Aug 11, 2011
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    12.4 is not below 12.0 so I have no answer to that question.
     
    #4 JimboPalmer, Aug 11, 2011
  5. Starcheckered

    Starcheckered Junior Member

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    You're right, 12.4 is not below 12.0... 11.6 is below 12.0
     
    #5 Starcheckered, Aug 11, 2011
  6. edthefox5

    edthefox5 Senior Member

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    Yes your battery is leaving you. Replace it. I bet you've had to jump it before too. But its not bad enough to cause that big of a loss in mileage.

    What causes that is the Inverter overheating due to either really poor condition coolant or the Inverter Coolant pump has failed. You will not even know its overheating either. No smoke..no steam...Until it gets so bad the INverter crowbars and leaves you on the side of the road.
    Check your cars VIN to see if your on the PUMP recall notice.
    You can see if the pump is working by taking the cap off the Inverter coolant tank and while the car is READY peek in there and you should see really good turbulence of the pink coolant. Lots of aggressive movement in the tank.

    Nothing improves mileage like brand new Inverter coolant.
    Its the easiest thing to do really.
     
    #6 edthefox5, Aug 15, 2011
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