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Battery increasingly full--a problem looming?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by snijd, Nov 30, 2009.

  1. snijd

    snijd DIY or die

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    Increasingly, I've noticed the battery reaching a full state--all bars green--following a trip down our hill to town. This used to be a rarity. In addition, I now see all but one green bars after driving back up the hill to home. Is this an indication of impending battery failure?

    This morning, I set the gearshift to "B" in an attempt to prevent reaching all green bars, but to no avail. The battery was still fully charged after this one mile drive down the hill.

    Problem, or not? This 2006 Prius has just under 34,000 miles. I'd appreciate some assessments.
     
    #1 snijd, Nov 30, 2009
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  2. efusco

    efusco Moderator Emeritus
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    Probably just the colder weather. With the climate control on the ICE tends to run longer and then stores extra energy in the battery. No need to adjust or adapt or use B-mode or anything.
     
    #2 efusco, Nov 30, 2009
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  3. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    As my Prius has aged, I've noted that the car is keeping it's charge level higher. I used to stay in the blue region, now it's green a lot (highway driving). I have 47k miles.
     
    #3 a_gray_prius, Nov 30, 2009
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  4. brick

    brick Active Member

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    I doubt this is a problem. For one thing, the Prius tends to maintain a higher SOC in cooler weather. Part of this is probably the fact that the A/C isn't run, but my observations indicate that there is a programming component to it as well. Another part of this is the fact that the battery capacity is actually smaller when the pack is cool. (That's just how NiMH is.) This is noticeable in the form of a battery that charges and discharges faster than it did during the summer. It could be that you are just better tuned into it this year, especially if your car is a few years old and you hear the voice in the back of your mind saying "I wonder if it's time to for something to go wrong?" Warning signs of a failing battery are **very** rapid charge and discharge. We're talking one bar to 8 bars and back at a truly alarming rate...seconds, not minutes. The behavior you describe sounds normal to me.
     
    #4 brick, Nov 30, 2009
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  5. snijd

    snijd DIY or die

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    Hopefully it's normal behavior. I'd never before seen it shut down in the green at our house, even last winter. Now it seems to happen regularly.
     
    #5 snijd, Nov 30, 2009
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  6. JimN

    JimN Let the games begin!

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    The warning sign is wild or rapid fluctuations between fully charged and discharged. I believe more green bars more often result from better driving and/or how the car is configured.
     
    #6 JimN, Nov 30, 2009
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  7. N3FOL

    N3FOL Member

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    I've seen all green bars on my Prius time to time. My Prius is slowly approaching 24K and it seems to run better and better as the miles pile up (knocking on wood).
     
    #7 N3FOL, Nov 30, 2009
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  8. uart

    uart Senior Member

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    As others have already stated, high SOC is not a problem. It's rapidly fluctuating SOC that indicates possible battery trouble.
     
    #8 uart, Nov 30, 2009
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  9. 2009Prius

    2009Prius A Wimpy DIYer

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    Is the fuel efficiency different from before? I remember reading someone observing the more green bar phenomenon together with lower fuel efficiency. The conclusion was that the battery does get old and not as good as new. Even though it still works, it is not as effective. :(
     
    #9 2009Prius, Dec 1, 2009
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  10. snijd

    snijd DIY or die

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    Mileage has dropped off, but I've been trying to justify it based on different tires, shorter trips. When we first got it, we were seeing over 50 mpg consistently. Now it's consistently in the high 30s. I've wondered whether living on a hill was harder on the traction battery--I've noticed that some of the folks who've experienced battery failures have lived on hills or in the mountains.
     
    #10 snijd, Dec 1, 2009
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  11. 2009Prius

    2009Prius A Wimpy DIYer

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    Well I guess it would be hard to tell until you have a chance to drive in a similar fashion as when you first got it. Yes different tires, short trips and hills all affect MPG. And yes my impression is also that hills kill batteries sooner. :(
     
    #11 2009Prius, Dec 3, 2009
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  12. hobbit

    hobbit Senior Member

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    At 120K on an '04 my original HV battery seems to be just fine,
    but it's definitely exhibited a couple of issues in cold weather.
    Less regen current allowed until enough cabin heat slowly seeps
    into the pack back there, and peaks as high as 270V during high
    charge rates even at the reduced 50 - 60 A limit. That points
    to higher internal cell resistance. But it's right back to normal
    in warm weather, so I wouldn't be too concerned.
    .
    _H*
     
    #12 hobbit, Dec 3, 2009
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