Cell block two melting around terminal

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Parrish21r, Nov 28, 2016.

  1. Parrish21r

    Parrish21r Junior Member

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    So I've had an up and down experience with our 06 Prius battery. I've rebuilt it 3 times all replacing cell block two. The cell melts around the back of the terminal every single time. It will last a couple months before it shorts out again. Does anyone know what the wires going to the ecu from cell block two power or as to why this keeps happening to this cell alone? I've balanced the pack out equal every time and done just as it was supposed to be done and always with new cells.(13-15 model Prius cell blocks). [/[ATTACH=full]120896[/ATTACH][ATTACH=full]120897[/ATTACH] attached is two pics of the damage.

    Posted via the [URL='https://siteowners.tapatalk.com/byo/displayAndDownloadByoApp?rid=87966']PriusChat mobile app[/URL].


     
    #1 Parrish21r, Nov 28, 2016
  2. andrewclaus

    andrewclaus Active Member

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    I can't see your photos.

    All the ECU wiring should be small signal/voltage detection only, and should be identical for all blocks. The wire is small enough that it would probably fuse if there were enough current to melt the module. I don't think that's the problem.

    Assume you've checked the obvious and have thoroughly cleaned the bus bar and nuts, and torque to spec? Could there be some metal pitting and you may need a new bus bar assembly?
     
    #2 andrewclaus, Nov 28, 2016
    valde3 likes this.
  3. Parrish21r

    Parrish21r Junior Member

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    Check that and everything seems fine. It's not swelling the cell just melting the plastic around the washer of the terminal

    Posted via the PriusChat mobile app.
     
    #3 Parrish21r, Nov 28, 2016
  4. valde3

    valde3 Senior Member

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    This pretty much profess that it has to be bad connection between the module and bush bar. You have find the reason why, and fix it. Maybe somebody can figure out something from the picture if you can get it posted here.
     
    #4 valde3, Nov 28, 2016
  5. Parrish21r

    Parrish21r Junior Member

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    #5 Parrish21r, Nov 28, 2016
  6. valde3

    valde3 Senior Member

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    Maybe it’s just the picture fooling me but it looks like the terminal on that module numbered 5 is at deeper level than the terminal on modules marked 2 and 6. If that’s the problem then maybe just coper washer might fix it?
     
    #6 valde3, Nov 28, 2016
  7. Parrish21r

    Parrish21r Junior Member

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    That's what I was talking about. That cell that's marked 5 was at the same level the rest and after a month of use it threw a code saying cell block two was weak. Opened pack up to find another cell(#5) had melted over the terminal shorting that cell out. Cell internal resistance and volts matches the rest but for some reason after about month it will do the same thing

    Posted via the PriusChat mobile app.
     
    #7 Parrish21r, Nov 28, 2016
  8. andrewclaus

    andrewclaus Active Member

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    If we can get a view of both surfaces of the copper bus and nut, it might help.
     
    #8 andrewclaus, Nov 28, 2016
  9. Parrish21r

    Parrish21r Junior Member

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    Both of those are clean and and clear. I just re washed them back to a smooth copper. There was a little acid but not enough for this to be happening repeatedly.

    Posted via the PriusChat mobile app.
     
    #9 Parrish21r, Nov 28, 2016
  10. valde3

    valde3 Senior Member

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    What I meant is the physical level of the terminal in the battery module. If that is not the same as modules besides it the bus bar can’t have a good contact. Should be very easy to check with anything strait and about correct length. Remember to remove the bus bars from other end of module if you use anything conductive.
     
    #10 valde3, Nov 28, 2016
  11. Parrish21r

    Parrish21r Junior Member

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    It was the same modules as the rest. That is where I'm talking about it melted the plastic around the terminal so it looks offset compared to the rest.

    Posted via the PriusChat mobile app.
     
    #11 Parrish21r, Nov 28, 2016
  12. jadziasman

    jadziasman Prius owner emeritus

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    You said module 2 each time but you show module 5 this time. Is this your 4th rebuild?

    Are you tightening the nuts onto the modules with specified torque (48 inch-pounds)? If not, that might be the reason you're
    having this issue. Never seen melting at the connection before - fascinating.
     
    #12 jadziasman, Nov 28, 2016
  13. Parrish21r

    Parrish21r Junior Member

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    That cell just says 5 from swapping cells around prior to the last build. But this was the 4th rebuild all from the same issue. I thought it was possible lose connection so I made sure they were all torqued properly and everything was clean still had the same end result.


    Posted via the PriusChat mobile app.
     
    #13 Parrish21r, Nov 28, 2016
  14. jadziasman

    jadziasman Prius owner emeritus

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    Two possibilities:

    1) The newer Gen 3 modules are not compatible with your older Gen 2 modules.
    You should buy a Gen 2 module as close in manufacturing date as to the others in your pack and see if this solves it.

    2) The signal wire from module 2 to the ECU or the ECU itself is faulty. Have you disconnected
    the frame wire harness to the ECU before? If not, if you find it doesn't come out of the ECU easily then
    there's corrosion or melting inside the connection.
     
    #14 jadziasman, Nov 28, 2016
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