Check Hybrid System (before and) after Grid charge

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Josh L, Oct 31, 2025 at 3:39 PM.

  1. Josh L

    Josh L New Member

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    My Check Hybrid System came on twice in a week (P0A80) so I made the time to grid charge the battery. Thanks to @Abarnabe, I followed his write-up to grid charge at 350mA and light bulb discharge as I understand it. It took 4 days, so I don't think I was too far off. I moved some modules around after the final charge based on voltages after resting for an hour to try to balance the pack.

    When I drove it the first time, no issues, but the second time "Check Hybrid System" came on.

    I load tested each module with a single H7 55w 12v headlight bulb for 2 minutes and didn't see anything dramatic. Maybe the lower voltages are unacceptable?

    module, start V, V @2 min-loaded, V @2m10s-no load
    1, 8.04, 7.75, 7.84
    2, 8.03, 7.65, 7.75
    3, 8.04, 7.74, 7.81
    4, 8.04, 7.65, 7.75
    5, 8.03, 7.74, 7.81
    6, 8.02, 7.6, 7.69
    7, 8.04, 7.67, 7.8
    8, 8.04, 7.72, 7.79
    9, 8.04, 7.67, 7.74
    10, 8.04, 7.7, 7.8
    11, 8.02, 7.59, 7.69
    12, 8.04, 7.66, 7.8
    13, 8.03, 7.68, 7.76
    14, 8.04, 7.7, 7.8
    15, 8.04, 7.7, 7.81
    16, 8.04, 7.74, 7.81
    17, 8.04, 7.75, 7.81
    18, 8.03, 7.68, 7.74
    19, 8.04, 7.75, 7.82
    20, 8.03, 7.63, 7.72
    21, 8.03, 7.73, 7.83
    22, 8.04, 7.61, 7.78
    23, 8.03, 7.72, 7.82
    24, 8.05, 7.69, 7.78
    25, 8.05, 7.62, 7.82
    26, 8.03, 7.64, 7.72
    27, 8.04, 7.72, 7.82
    28, 8.06, 7.75, 7.84

    Another observation about grid charging, the charge from 101 to 238v only took about 8 hours. At 350mA, that's only 2.8AHr, seems low. I charged for an additional 6 hours to balance the cells. The charge from 84 to 238v took only 12 hours, I again let it go another 6 hours for 18 total. I didn't have the right bulbs so I used 40w bulbs in various configurations to try to get to 200, 75 and 25w, so my discharge times were inconsistent.

    I have the Dr Prius second by second recorded data for the most recent P0A80, if it would be helpful I can try to post a Google Sheets link. It was picking up my kid from school, so gently accelerating (1.34 ft/s^2, 0.04g) from 0mph to 11mph. SOC dropped from 53% to 27%. Pack voltage was 202 at 53% SOC, which seems like a mismatch.

    I would really appreciate some guidance as to next steps. Another grid charge session? A longer / higher load test to ID bad modules? Swap modules? Replace modules? Which ones? Thanks!
     
    #1 Josh L, Oct 31, 2025 at 3:39 PM
    Last edited: Oct 31, 2025 at 5:22 PM
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  2. Abarnabe

    Abarnabe Member

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    error P0A80, is an imbalance.
    I learned that a 55 w load test is too less, the modules ar subject to 130A load while driving.
    Try to run a full battery test in dr. prius, it should tell you which module is failing.
    If the feature is locked please post a screenshot of dr prius battery monitor during hard acceleration with soc at around 40/45% ( you need an assistant here :), the modules with highest internal resistance are the problematic ones, the y are marked in red ,orange, or yellow.
    You probably need to replace one or more modules that can't recover with a reconditioning.
     
    #2 Abarnabe, Nov 1, 2025 at 8:30 AM
    Last edited: Nov 1, 2025 at 8:43 AM
  3. Brian1954

    Brian1954 Senior Member

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    The freeze frame data for the P0A80 code will show the voltages of all 14 battery blocks when the code was triggered. Using that information, you can see which battery blocks are the lowest voltages and concentrate on the modules in those blocks. You need a good scanner that is capable of reading the freeze frame data.

    Is this the same car that you created an earlier thread about, https://priuschat.com/index.php?posts/3526518 ?
    If so, I would recommend that you replace the complete hybrid battery with a new or refurbished battery.
     
    #3 Brian1954, Nov 1, 2025 at 9:17 AM
    Last edited: Nov 1, 2025 at 9:23 AM
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  4. Josh L

    Josh L New Member

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    Thanks Abarnabe, all the IR's are 20 because I cleared the battery codes recently.

    Thanks Brian1954, yes this is the same car and battery as you linked. I want to try to fix this battery before I buy a new / professionally reconditioned assembly. Funds are tight right now.

    Thanks to both, the freeze frame at 26A clearly shows #2 and #14 are low! Time to start playing whack-a-mole :cry:
     
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  5. Brian1954

    Brian1954 Senior Member

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    What do you mean by "the freeze frame at 26A"? Do you mean the Dr Prius app data? That is not the freeze frame data.

    You need to look at the freeze frame data for the P0A80 code using a good scanner that is capable of reading freeze frame data. Here is an example of the freeze frame data in Techstream. https://attachments.priuschat.com/attachment-files/2024/08/253941_Freeze_Frame_Data_08-03-24.pdf
     
    #5 Brian1954, Nov 1, 2025 at 12:29 PM
    Last edited: Nov 1, 2025 at 1:57 PM
  6. Abarnabe

    Abarnabe Member

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    if you drive 10 minutes on electric between 40 and 50 soc, it will display / refresh actual internal redistance.
    Usually the modules in the middle fail first due to higher temp
     
    #6 Abarnabe, Nov 1, 2025 at 1:38 PM
    Last edited: Nov 1, 2025 at 2:06 PM