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Is my battery swollen?

Discussion in 'Gen 2 Prius Technical Discussion' started by rekonditioned, Sep 16, 2023.

  1. rekonditioned

    rekonditioned New Member

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    I finished cycling my battery modules with hobby chargers. They are all still in the compression block. Most have been sitting for >2 days, while some finished cycling >24 hours ago.

    Looking at the underside, I think I see a slight buldge / curve of the white compression block pictured in this photo.
    I have copied the photo and annotated where I see the curvature.

    Should I wait before loosening the compression blocks?
    Is this normal?


    Thank you
     
    #1 rekonditioned, Sep 16, 2023
  2. rekonditioned

    rekonditioned New Member

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    #2 rekonditioned, Sep 16, 2023
  3. PriusCamper

    PriusCamper Senior Member

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    Yes... If the pack gets hot enough those plastic end caps will hold the shape they were melted into, but mostly on the bottom, not so much on the top. You can buy used replacement ones online. As for the modules, the prism design with thin foil sides can go from curved to flat again once they heat up, as long the white plastic end caps are flat. Though that slight curve might no make much of a difference other than maybe making the pack slightly more prone to physical failure if it heats up that bad again.
     
    #3 PriusCamper, Sep 16, 2023
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  4. pasadena_commut

    pasadena_commut Senior Member

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    Is there a picture of that region from before the reconditioning?

    The amount of warp is very small, and if it was already present, it might not be worth worrying about it.
     
    #4 pasadena_commut, Sep 17, 2023
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  5. rekonditioned

    rekonditioned New Member

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    Thank you for the reply and help folks.
    Unfortunately, I don't have a prior photo. I'm going to keep an eye on it from now on.

    After another >12 hours, I removed the white compression plate and did not see any visible swelling of the modules (good news).

    During the previous repair I simply racked-up the modules and tightened the compression plates in one go.
    In retrospect, I think I should have tightened in two phases. First, tighten until compression is tight but not all the way. Then wait maybe 1 day for the modules to settle.
    Then tighten all the way.
    While you can tighten all the way without waiting, I think it's too much force on the plastic plate and that may have given it no choice except to bow a little.
    Or maybe I'm overthinking :D
     
    #5 rekonditioned, Sep 17, 2023
  6. pasadena_commut

    pasadena_commut Senior Member

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    Did you use a torque wrench when tightening? Given the "narrow spacing on one side and wide spacing on the other" design, having different amounts of tension on the rods could cause the plate to warp. Although if that was the case, I would have expected warping at both ends.
     
    #6 pasadena_commut, Sep 18, 2023
  7. rekonditioned

    rekonditioned New Member

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    Yes, I used a torque wrench on these bolts. I used the value from the ChrisFix youtube video.

    As you wrote, the top has narrow spacing between the rods while the bottom has wide spacing. This is definitely consistent with the slight warping that I see on top and bottom.
     
    #7 rekonditioned, Sep 18, 2023
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