Does this sound like evidence of two bad modules?

Discussion in 'Gen 2 Prius Technical Discussion' started by Valualv, Oct 20, 2020.

  1. Valualv

    Valualv New Member

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    Hi all! I have an '06 with 140k miles. Drove it a couple of weeks ago and got red triangle of death and a couple other lights. Upon trying to re-start it, wouldn't go into "ready" or drive or reverse. Couldn't get it to go into ready mode until yesterday. Was finally able to use techstream to pull P0AA6/612.. So I have a leak in EV battery somewhere. I used techstream to check the voltage of each pack and from what I can see as a total novice, it looks like pack 1 and 14 may need to be replaced. Does it look that way to you all?

    Either way, I'll definitely have to open the battery pack up and take a look. I learned the voltmeter method of identifying a leaky module once it is safely removed but if I can tell if I need to buy a few modules or a whole new pack before I start that process so that I can change it out in one go, that would be nice.

    I have read and watched endless forums and youtube videos and have figured out what I believe to be the most precautions I can take to avoid danger as I remove the pack. This is what I think, please let me know if there are further precautions I should take:
    - Class 00 gloves on at all times
    - Firstly, remove orange safety clip
    - After disconnecting main wires from pack, use voltmeter to verify proper disconnect (how exactly is this done?)
    - Once pack is out, let sit for about 15 minutes before removing bus bars
     

    Attached Files:

  2. Aegean

    Aegean Member

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    The voltage of module 1 and 14 appears normal. If you had a blown cell in either module it would be a full 1.2v less like 14.90.

    Also, I had the hybrid battery fail in both my Prius and the cars were going to Ready without issues. Start by researching the codes first before you dismantle the battery.
     
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  3. Valualv

    Valualv New Member

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    Well I did research the code and it means that there's a leak in my battery pack somewhere...
     
  4. Aegean

    Aegean Member

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    Keep us posted what you will find. I am sure you realize that in your particular case with a high voltage leak you should be extremely careful when you work on the battery.
     
  5. dolj

    dolj Senior Member

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    Why are you starting a new thread for the same problem? Don't do that it will only create confusion for both you and people trying to help you.

    The other thread has good information you should go with and just stay with that thread too.

    And to answer your thread title, no, it doesn't.
     
    #5 dolj, Oct 20, 2020
    Last edited: Oct 20, 2020
  6. davecook89t

    davecook89t Senior Member

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    I agree that you cannot make a conclusion about which modules might be in need of replacement based on your single snapshot. A log of block voltages from Torque Pro or a graph from Hybrid Assistant over the course of a 15 or 20 minute road trip would be more conclusive. Your difference of .34V between the lowest voltage block and the highest voltage block is just above the .3V that might trigger a code for an out of balance condition in your battery's modules, but I believe the code will not be thrown unless the difference is consistently above .3V, which cannot be proven based on one screen shot. Further, the pattern of the outer blocks (1 and 14) having a lower voltage that the others is the same as I have seen on our Gen 2 after it has been sitting idle for a few days, and the same as others have reported. It seems that having only one adjacent module rather than the normal 2 allows the outer modules to discharge at a slightly higher rate. I have seen this pattern in our car for the 4 years we have owned it and it has yet to throw a code.

    It is not likely that you will be able to identify the leaking module(s) on the basis of its (their) voltage readings alone. The leak is probably slow enough that natural variability of voltages between the modules will disguise the leaking one(s). In fact, the modules may not be leaking at all. The repair manual describes the Detection Condition for P0AA6-612 as follows:

    Insulation
    resistance of
    HV battery,
    battery ECU,
    system main
    relay, or system
    main resistor is
    low.

    The Trouble Area is described as follows:

    - HV battery
    assembly
    - Battery ECU
    - System main
    relay
    - System main
    resistor
    - Main battery
    cable
    - No. 2 main
    battery cable
    - Battery plug
    - No. 2 frame
    wire
    - Junction block.

    So your first task is to verify that the leak is coming from the modules themselves (HV battery assembly), rather than the other trouble areas listed. To do that you do not even need to take the battery out of the car, as shown in the 2nd video of @strawbrad's Post #12 in this thread.

    Try that first and let us know how it goes before digging deeper into what is causing your car's issues.
     
  7. dolj

    dolj Senior Member

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    Not necessarily. With this particular code battery modules can and often do behave perfectly normally with regard to voltage and capacity.
    The sub-code 612 (see screenshot in the first post) serves the same purpose and is more reliable.

    This was also covered in the other thread, BTW.
     
    #7 dolj, Oct 20, 2020
    Last edited: Oct 20, 2020
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  8. davecook89t

    davecook89t Senior Member

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    Right, I was not saying that would help to find a leaking module, only that it might help to identify a weak one.
     
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