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Low mpg with new HV battery

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by canadice2, Feb 5, 2014.

  1. canadice2

    canadice2 Junior Member

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    My 2006 Prius HV battery recently died after 144,000 miles. I spent the $3ooo and got a new battery. To my surprise my mileage has dropped from 45 to 37 mpg. I contacted the dealer repair shop and they told me that the computer system needs to "re-learn" how to optimize the synchronization between gas engine and electric motor. The process can take 2 to 5 thousand miles. Has anyone heard of this before. Thanks
     
    #1 canadice2, Feb 5, 2014
  2. JC91006

    JC91006 Senior Member

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    What state are you in? How long have you had this battery installed? The computer that does the mpg average takes a little while to do the averages. It may take a few hundred miles or possibly a thousand. I don't think 2 to 5000 is realistic.
     
    #2 JC91006, Feb 5, 2014
  3. bisco

    bisco cookie crumbler

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    hogwash. how many tanks have you driven on the new battery? how old is your 12 volt battery?
     
    #3 bisco, Feb 5, 2014
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  4. canadice2

    canadice2 Junior Member

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    I'm in NY. The battery is 3 weeks old. I would think that the computer's average function would start at the first mile. I believe the dealer was referring to how the electirc and gas systems interact.
     
    #4 canadice2, Feb 6, 2014
  5. canadice2

    canadice2 Junior Member

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    I'm probably on my 3rd or 4th tank of gas. The 12 volt battery is probably a couple years old. I'm smelling some hogwash as well. Thanks
     
    #5 canadice2, Feb 6, 2014
  6. JC91006

    JC91006 Senior Member

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    If you are in NY and you only have 144,000 miles on your car, you shouldn't have paid anything for your HV battery. You are covered until 150,000 miles.

    I would give it a little more time before you can determine the average mileage. I would definitely get my $3000 back from the dealer.
     
    #6 JC91006, Feb 6, 2014
  7. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Or could it be as simple that it's winter and the mpg average displayed by the trip computer was over the last few thousand miles and included some summer mpg's?

    Since the new HV battery was installed the trip computer has been reset and is now just averaging winter mpg's.

    Give it a few more months and the warmer weather will drag your average up again. Oh and check your tyre pressures.
     
    #7 GrumpyCabbie, Feb 7, 2014
  8. theshark

    theshark Member

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    Did you get your money back!?!
     
    #8 theshark, Feb 7, 2014
  9. vskid3

    vskid3 Active Member

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    Have you checked the tire pressure? If you were running higher pressure before, some shops will reduce it to the recommended pressure. Probably wouldn't cause that much of a difference, but could account for part of it.
     
    #9 vskid3, Feb 7, 2014
  10. canadice2

    canadice2 Junior Member

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    In 2006 there were 2 type of warranties for the HV battery in NY, 100,000 and 150,000. My understanding of the 150,000 warranty is that it only applied to vehicles sold in NY with a CA hybrid system. Most vehicles in NY in 2006 did not have the CA system. That's not the exact language in my warranty docs but it is something like that. IF you know something different I'd love to see the documentation.
     
    #10 canadice2, Feb 10, 2014
  11. canadice2

    canadice2 Junior Member

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    I'm beginning to question the 12 volt battery. Once outside temp gets above 10 - it's been a brutal winter - I'm going to check the battery using the procedure described at elearn aid. If it is the 12 volt battery I'm still puzzled why putting in a new HV battery might affect it. Maybe it was bad before and now with a reset mileage buffer the problem is noticeable
     
    #11 canadice2, Feb 10, 2014
  12. bisco

    bisco cookie crumbler

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    the problem is how they treated the battery while it was in the shoppe. battery is a bit along in years, (you say a couple, which isn't that old) they run it down while working on your car (what do they care) next thing you know, your mpg's are low because your ice is running to charge the hv battery which is charging the 12 volt.
     
    #12 bisco, Feb 10, 2014
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