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Re: LiFePo4 upgrade

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  • Mike Phillips
    Bouty, I have the same questions about weather or not you are using a BMS or not. Here s why. I ran a few 40ah cells in my truck for 400 miles of total
    Message 1 of 6 , May 14, 2009
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      Bouty,

      I have the same questions about weather or not you are using a BMS or not. Here's why. I ran a few 40ah cells in my truck for 400 miles of total driving. Only one time did I overcharge them just slightly and when I pulled them to check their capacity, they dropped 10% instantly. No idea how that one overcharge effected their cycle life. I've developed an analog BMs board in the mean time, so when I feel like putting lithium back in I can better protect the cells.

      I agree that the vehicles operate much more efficiently with the lighter weight packs. When my truck lost 1000lbs, it got crazy good efficiency (as low as 180 wh/mi and 200 wh/mi on long trips)on a 4000lb truck.

      Mike
    • d. Bouton Baldridge
      Mike, I wanted to see how the cells would perform without any BMS, although the manufacturer recommends them. The first charge with the Zivan did some
      Message 2 of 6 , May 14, 2009
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        Mike,
        I wanted to see how the cells would perform without any BMS, although the manufacturer recommends them. The first charge with the Zivan did some interesting things with voltage and frequency at the end of the routine, and the first charge the balance was very good, and since  it is not over charging I have a slight comfort zone Of course it could . I have heard that the early itterations of Thundersky had bad batches, I am hoping that the new chemistry is more forgiving,...we'll see. Gotta start somewhere.
        Bouty  

        --- On Thu, 5/14/09, Mike Phillips <mikep_95133@...> wrote:


        From: Mike Phillips <mikep_95133@...>
        Subject: [solectria_ev] Re: LiFePo4 upgrade
        To: solectria_ev@yahoogroups.com
        Date: Thursday, May 14, 2009, 9:16 PM








        Bouty,

        I have the same questions about weather or not you are using a BMS or not. Here's why. I ran a few 40ah cells in my truck for 400 miles of total driving. Only one time did I overcharge them just slightly and when I pulled them to check their capacity, they dropped 10% instantly. No idea how that one overcharge effected their cycle life. I've developed an analog BMs board in the mean time, so when I feel like putting lithium back in I can better protect the cells.

        I agree that the vehicles operate much more efficiently with the lighter weight packs. When my truck lost 1000lbs, it got crazy good efficiency (as low as 180 wh/mi and 200 wh/mi on long trips)on a 4000lb truck.

        Mike



















        [Non-text portions of this message have been removed]
      • Mike Phillips
        Thundersky s are not forgiving in the least. That s the brand I used for my 400 mile test. Now they have 10% less capacity. I have a professional load tester
        Message 3 of 6 , May 14, 2009
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          Thundersky's are not forgiving in the least. That's the brand I used for my 400 mile test. Now they have 10% less capacity. I have a professional load tester that I checked them on before I installed them in the truck.

          There is no way for you to know if you overcharged them or not without monitoring each cell or using a BMS. It's your money. I would not presume to tell you how to spend it. But guessing is not a cheap route.

          Mike



          --- In solectria_ev@yahoogroups.com, "d. Bouton Baldridge" <cfrkeepr@...> wrote:
          >
          > Mike,
          > I wanted to see how the cells would perform without any BMS, although the manufacturer recommends them. The first charge with the Zivan did some interesting things with voltage and frequency at the end of the routine, and the first charge the balance was very good, and since  it is not over charging I have a slight comfort zone Of course it could . I have heard that the early itterations of Thundersky had bad batches, I am hoping that the new chemistry is more forgiving,...we'll see. Gotta start somewhere.
          > Bouty  
          >
          > --- On Thu, 5/14/09, Mike Phillips <mikep_95133@...> wrote:
          >
          >
          > From: Mike Phillips <mikep_95133@...>
          > Subject: [solectria_ev] Re: LiFePo4 upgrade
          > To: solectria_ev@yahoogroups.com
          > Date: Thursday, May 14, 2009, 9:16 PM
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          > Bouty,
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          > I have the same questions about weather or not you are using a BMS or not. Here's why. I ran a few 40ah cells in my truck for 400 miles of total driving. Only one time did I overcharge them just slightly and when I pulled them to check their capacity, they dropped 10% instantly. No idea how that one overcharge effected their cycle life. I've developed an analog BMs board in the mean time, so when I feel like putting lithium back in I can better protect the cells.
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          > I agree that the vehicles operate much more efficiently with the lighter weight packs. When my truck lost 1000lbs, it got crazy good efficiency (as low as 180 wh/mi and 200 wh/mi on long trips)on a 4000lb truck.
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          > Mike
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