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New Testing Block Check

Discussion in 'Gen 2 Prius Technical Discussion' started by Todd Stepp, Apr 19, 2023.

  1. Todd Stepp

    Todd Stepp Junior Member

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    So this time I followed the advice of someone here on the boards.
    Looks like Block 11 is the weak one, with 5 and 10 being stellar (by comparison) and the rest in the middle.
    upload_2023-4-19_14-8-44.png
    Once warm, turned off the ignition, put in the reader and started up with max AC and let it run a few cycles.
    This is the second cycle with no intervention, recharge RPM was 1280:

    During the recharge before this one, I pressed the brake and accerator to get the RPMS up so the starting voltage was higher, recharge RPM was 2496: upload_2023-4-19_8-28-57.png
     

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    #1 Todd Stepp, Apr 19, 2023
    Last edited: Apr 19, 2023
  2. pasadena_commut

    pasadena_commut Senior Member

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    If modules are out of balance it is bad, either way. That said, having one which is much weaker than the others is worse than having one which is much better. Ideally all of those traces would be right on top of each other. If you grid charge this pack with a low current for a long time you might be able to push the weaker modules up to the same starting voltage as the strong ones. It likely won't stay that way though. Cells dry out and/or are damaged over time, which means that the module containing it will not keep up with the healthier modules. Note that in your chart the K module is not only lower to start with, but even lower than expected at the end of the discharge. It might be interesting to normalize the starting voltages of all modules and plot again. That is, subtract the voltage at 0 time from the points along the entire plot for each module. That will show the net voltage drop for each module over time.

    Not relevant here, but there is apparently an issue with the LiFePO4 pack where one weak module which could not be fully charged resulted in overcharging of the strongest modules, which then failed. I don't know if they have a fix for that yet. Oddly that is backwards from the NiMH packs, where it is usually the weaker modules which give up the ghost first.
     
    #2 pasadena_commut, Apr 19, 2023
    Last edited: Apr 19, 2023
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  3. Todd Stepp

    Todd Stepp Junior Member

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    For Cycle 2 you see #11 deviate and dropping faster:
    upload_2023-4-19_19-45-58.png
    By the time you get to the 5th cycle, the blocks are pretty much matched in their drop curves:
    upload_2023-4-19_19-47-8.png
     
    #3 Todd Stepp, Apr 19, 2023
  4. dolj

    dolj Senior Member

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    Can you define for us what you mean by cycle, and how exactly are you cycling the battery? Is this all in-car using the engine to charge and applying load to discharge? If so, to what level are you discharging?
     
    #4 dolj, Apr 19, 2023
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  5. Todd Stepp

    Todd Stepp Junior Member

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    Recondition is done and installed! Dr.Prius reported 20% prior to recondition and is now reporting 82%!
    I replaced one bad cell (failed load test miserably, and three other low capacity cells. One more should have probably been replaced but I only had 4 cells.
    This beast is almost cleaned up and ready for market!
    Thanks for the help here at Prius Chat.
     
    #5 Todd Stepp, Jun 1, 2023
  6. Carall

    Carall Member

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    If it was gen. 2 prius battery, 82% is very low result for a reconditioned battery. A good reconditioned gen. 2 battery will report over 100% on dr. Prius.
     
    #6 Carall, Jun 22, 2023
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