Replaced bad cells but not always charging

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Keith H, Aug 14, 2018.

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  1. Keith H

    Keith H New Member

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    Hello all! My son and I recently replaced several cells of his Gen II Prius. After a few failed attempts we did it right this time, doing charge/discharge tests on each cell to find the bad ones. I feel confident about that work. Afterwards, we cleared the error codes and test drove without a problem.

    The car runs great for a while, then the battery meter keeps dropping as if it can't charge and the check engine light comes on. When I unplug the little 12V for two minutes and plug it back in, everything is fine again. The battery display jumps up and I see it charging/discharging normally. The codes vanish.

    During all this the powertrain seems to run OK. It accelerates decently but it seems this cycle repeats every day or two. Any ideas what that could be?
     
    #1 Keith H, Aug 14, 2018
  2. JC91006

    JC91006 Senior Member

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    What did you use to charge and discharge the modules? Did you test the replacement modules? Was the pack balanced afterwards?
     
    #2 JC91006, Aug 14, 2018
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  3. Keith H

    Keith H New Member

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    Discharged with a setup that hooks a car light and volt meter into a circuit so we can time each cell's drop through a voltage range under load. Recharged with a smart charger. I'm not too sophisticated about balancing schemes but we paired them by characteristics.
     
    #3 Keith H, Aug 14, 2018
  4. PriusV17

    PriusV17 Active Member

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    Try to get a voltage reading of all 14 modules through an ODB2 scanner especially when the problem happens.
     
    #4 PriusV17, Aug 14, 2018
  5. ericbecky

    ericbecky Hybrid Battery Hero

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    This.
    For less than $75 you will have the tools to read and clear codes plus see hybrid battery data live.
    - Android phone/tablet
    - obdii elm 327 bluetooth adaptor
    - torque pro app

    Then you can see data live including each of the 14 hybrid battery blocks.

    Unhooking the the 12v simply makes the car temporarily forget it is broken. It is not fixing anything. You do not need to wait 2 minutes. U hooking fofor even as little as a few seconds clears the memory.

    You clearly have some problem that has not been addressed. You'll need more data to find out what it is.

    Feel free to call if you want to talk through some ideas.
     
    #5 ericbecky, Aug 14, 2018
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  6. Keith H

    Keith H New Member

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    Thanks Eric. I had my son get Torque Pro on his phone and I bought a compatible ODB II plug-in but I think he had some problem loading the Prius PIDs into Torque. I'll get him to resolve that and do a complete scan. Is there an online guide you can recommend for doing battery rebuilds, including cell-balancing?
     
    #6 Keith H, Aug 15, 2018
  7. ericbecky

    ericbecky Hybrid Battery Hero

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    The pids come preloaded, you just need to "activate" them....
    Settings
    Manage extra pids/sensors
    In the upper right, click on the three dots
    Add presefined set
    Prius gen 2 (2004-2009)

    I don't really know of any good guides.
    I try to avoid doing this at all costs.
    Ot does not last and can be quite frustrating.
    Keep doing it as long as it is still fun for you.
     
    #7 ericbecky, Aug 16, 2018
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