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Prius HV Battery High Resistance - Discussion

Discussion in 'Gen 3 Prius Technical Discussion' started by Shady551122, Sep 20, 2022.

  1. Shady551122

    Shady551122 New Member

    Joined:
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    Location:
    Jordan
    Vehicle:
    2010 Prius
    Model:
    Four
    Hello Friends

    I have a 2010 Prius , the HV battery had some issues and i replaced 4 cells in it , while monitoring the battery I found out that block 5 resistance is higher than the remaining blocks ( for Example Block 5 is 28milliohm while all the remaining blocks are in the range of 22-23 milliohm using Dr.prius App and these values reach the 34 milliohm for block 5 while the remaining block never exceeds the 28milliohm value) i thought there is an issue with the cells it self since i already cleaned the busbars properly , so i changed the cell with different ones however the values for the same block are still higher than the remaining blocks , thus i changed the position of 2 blocks (block 5 and 6) to check the issue however even after the changing block 5 still reads the highest values (Cells in Block 6 was 22 milliohm before the change and it reached 29 milliohm after i installed them on block 5) so i was wondering what might be the causes for the high resistance values only on block 5 ? how does the system read the milliohm values ? and what can i do to rectify this issue ?

    thank you in advance
     
  2. ChapmanF

    ChapmanF Senior Member

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    Vehicle:
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    IV
    It computes the block's internal resistance by observing the block's voltage when no current is flowing, and then observing how much that voltage drops when a known current flows. The voltage drop divided by the current is the resistance. By looking at the voltage drop as soon as practical after the no-current voltage, the ECU tries to get just the drop due to internal resistance, and not due to discharge of the block.
     
  3. Shady551122

    Shady551122 New Member

    Joined:
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    Location:
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    Vehicle:
    2010 Prius
    Model:
    Four
    thank you for these information's , so it detects the internal resistance when i start accelerating the car right ? and does it keep detecting it regularly ? or only one time ?
     
  4. ChapmanF

    ChapmanF Senior Member

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    IV
    My assumption is that it updates the values regularly while driving. But the battery ECU firmware is not published.