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HV Battery issue

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Eric C, Oct 26, 2014.

  1. Eric C

    Eric C New Member

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    I have problems with the battery on my 2006 Prius with 183k miles on it. The first time it happened A few months ago I received an error code P0a80 and another code indicating which cell should be dead. I reed the voltage on all the cells and found the dead one and replaced it with a good cell and everything was fine when I put the battery back in. It has been fine for about 5 months. Today the code P0a80 and the triangle and warning lights popped on again. No indicator of which cell might be dead though. I removed the battery and checked all the cells none of them seem to have a problem. I am wondering is there a way to check the ECU unit to see if that has a problem and if so is just replacing it ok or does it need to be reprogrammed for the car?
     
    #1 Eric C, Oct 26, 2014
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. You can replace the traction battery ECU without regard to any "reprogramming".
    2. If you get Mini VCI you can track battery module pair voltage dynamically as the car is being operated.
    3. You might have to drive the car for a while longer, before the failing module pair will become evident via a DTC.
    4. I am not aware of any way to test the traction battery ECU other than by replacement. However before you replace it make sure that all sense wires are intact and providing module pair voltages to the ECU.
     
    #2 Patrick Wong, Oct 26, 2014
  3. 3prongpaul

    3prongpaul Hybrid Shop Owner, worked on 100's of Prius's

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    Battery ECU's rarely fail. I've replaced 1 ECU and well over a hundred hybrid batteries.

    Battery ECUs can be swapped out without any registration process to the car if you want to try, but I doubt it will fix your car.

    How did you determine none of the modules have a problem? Visually? With a voltmeter at rest?
    Without a load attached a voltmeter won't tell you all the info you need. Techstream while driving is helpful, but ideally you need to know internal resistance, relative voltage under load, Delta SOC, and ah capacity to determine if the modules are ok.

    You probably have the "next worst" modules failing. Welcome to "whack a mole".
    You can clear the codes for a bit, but they'll be back.
     
    #3 3prongpaul, Oct 26, 2014
  4. Eric C

    Eric C New Member

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    Yeah I just used a voltmeter at rest last time and the bad cell was apparent. So far this time all the cells are reading at near 8 volts. I just ordered a Mini VCI and will put the battery back in and drive with it a bit when it comes in on tuesday to see if i can figure out which is bad.
     
    #4 Eric C, Oct 26, 2014
  5. Eric C

    Eric C New Member

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    I used the mini-vci with techstream it seems block 11 is weak. I am not sure how to determine which cells are part of block 11 though can anyone help?
     
    #5 Eric C, Oct 28, 2014
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I believe the numbering starts on the traction battery ECU side. Each block is composed of two modules so block 11 would be composed of modules 21 and 22, near the right side of the traction battery case. When you open the battery case up, measure the voltage of each module again. Hopefully you will find that either 21 or 22 shows a lower voltage than the others.
     
    #6 Patrick Wong, Oct 28, 2014
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