Load test results, cell replacement, only 1 bad cell module?!

Discussion in 'Gen 2 Prius Main Forum' started by Totallylost, Feb 18, 2018.

  1. Totallylost

    Totallylost Member

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    Hello all: I was hoping someone can help me since we have completed the load test with a 55w 12 volt bulb and a voltmeter (120 seconds per load test). See below for results of each cell module. My question is: Why could have the Toyota Dealership Diagnostics Report reflect that both Blocks 5 and 6 were "weak", but when I did the individual load test on each cell module, only cell module #10 (Block 5) is showing a big drop. I do not see much of a difference in the others. We have replaced cell module #10. Others that reflected somewhat of a drop, were tested again, but I do not notice a significant drop like in the one that has been replaced (cell module #10 in block 5). Am I missing something? I ask since as per the dealership diagnostics, block #6 should have had a bad cell too (meaning, I should have noticed a significant drop in cell modules 11 or 12 (block #6), correct?) Still confused and Totally lost :( See below for results.


    LOAD TEST RESULTS (2ND TEST DONE ON THOSE WITH HIGHEST VARIANCE/DROP)

    1. 7.50-7.31=.19

    2. 7.50-7.31=.19

    3. 7.46-7.27-.19

    4. 7.50-7.29=.21

    5. 7.53-7.32=.21

    6. 7.51-7.31=.20

    7. 7.54-7.31=.23

    8. 7.55-7.33=.22

    9. 7.53-7.31=.22

    10. 6.01-5.72=.29 **CELL MODULE #10 in block 5-**TO BE REPLACED**

    11. 7.66-7.41=.25 **block Number 6-2nd load test 7.49-7.30=.19

    12. 7.63-7.39=.24 **block Number 6-2nd load test 7.53-7.31=.22

    13. 7.67-7.40=.27 **block Number 7-2nd load test 7.55-7.32=.23

    14. 7.63-7.37=.26

    15. 7.63-7.38=.25

    16. 7.67-7.41=.26 **block Number 8-2nd load test 7.55-7.32=.23

    17. 7.66-7.41=.25

    18. 7.48-7.29=.19

    19. 7.67-7.43=.24

    20. 7.63-7.41=.22

    21. 7.66-7.41=.25

    22. 7.67-7.43=.24

    23. 7.61-7.38=.23

    24. 7.59-7.35=.24

    25. 7.65-7.42=.23

    26. 7.65-7.41=.24

    27. 7.66-7.42=.24

    28. 7.32-7.14=.18

     
  2. jadziasman

    jadziasman Prius owner emeritus

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    Your load test duration is not long enough to get a true indication of the capacity of each module.

    When I tested the modules in my HV pack, I discharged them with a halogen 12V headlight bulb with the high and low beam filaments connected until they reached 6V. Strong modules took twice as long to discharge to 6V than the weak ones. It's been almost two years since I did this so I cannot recall how many minutes it took to discharge them. What I can remember is the weak modules had less than 2.5 Amp-hours capacity and the best had over 6 Amp-hours.

    I recommend that you test both modules in block 6 for capacity (by measuring the time in minutes it takes to discharge from full to 6V).
     
    #2 jadziasman, Feb 18, 2018
    Last edited: Feb 18, 2018
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  3. Totallylost

    Totallylost Member

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    thank you :) I will keep everyone posted on how it goes.
     
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  4. ericbecky

    ericbecky Hybrid Battery Hero

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    Make sure you have a way to watch the voltage while the pack is installed. This will give you a true indication of what is going on. The weak or failing modules will be obvious.
     
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  5. Totallylost

    Totallylost Member

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    Hi and good morning: :) I will give that a shot and keep everyone posted :)
     
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  6. bisco

    bisco cookie crumbler

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    i'm getting confused between your two threads.(n)
     
  7. kenoarto

    kenoarto Senior Member

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    Interesting testing, but If one cell is bad, you should replace the whole pack. Individual cell replacement just doesn't work for most people.
     
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  8. jadziasman

    jadziasman Prius owner emeritus

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    Wouldn't Toyota just love that.

    Pack repair is a band-aid to be sure. But some folks don't need and don't want to invest $2000 or more for a new pack when their Prius is near end of life - like mine was. It makes perfect sense to "prolong" the life of the existing pack by a repair for many.
     
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  9. Prodigyplace

    Prodigyplace Senior Member

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    They can spend $1600 to install @2k1Toaster 's new cell kit then and recoup some of the cost by selling any good modules.
     
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  10. kenoarto

    kenoarto Senior Member

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    Says the man who no longer owns a Prius! Did you also spend/waste $500 on a balancing device in a futile attempt to patch your old battery? A genuine Toyota battery can be purchased today for as low as $1625. Add a few hundred for install and you get a 3 year warranty, too!
     
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  11. Prodigyplace

    Prodigyplace Senior Member

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    For comparison if DIY the Toyota pack would have a 1 year warranty & the kit of new cells has 2 year unlimited miles warranty. I believe it is currently backordered though.
     
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  12. William Redoubt

    William Redoubt Senior Member

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    I am not a hybrid drive specialist, but have worked with electricity for many years. It's not just the cells you have to worry about, it is also the connections. Did you notice any corrosion on the connections?
     
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  13. Totallylost

    Totallylost Member

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    Hi and thank you for your response. And yes, there was A LOT of corrosion. They have been cleaned out and now look like shiny pennies and nickels. Very good your question:)
     
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  14. Totallylost

    Totallylost Member

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    Hi :) I'm sorry if I confused you. Pretty much, I am confused too! I only found 1 bad cell module after the load test but the dealership stated both blocks 5 and 6 were "weak". Leading to make me believe that I am missing something perhaps? We have not received the Prolong discharger and charger. When I receive it, I will wait for Jeff652 and his company on how to proceed. :)
     
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  15. bisco

    bisco cookie crumbler

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    No worries, it is just a bit more difficult to keep having to go back and forth to see each reply.
     
  16. jadziasman

    jadziasman Prius owner emeritus

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    Okay kenoarto, calm down. I didn't say you were wrong. I merely gave the OP encouragement to continue working on his project because it's cheap and kind of fun to do.

    My Prius had 256K miles on it and it was burning oil. It was almost 12 years old. It became a "beater". I considered installing a new pack in it but even at $1650 that would have been risky considering that things like the combination meter and the MFD failing could have happened in the next few years

    So instead I "donated" it to another Prius enthusiast. The buyer was overjoyed. Another toy for him to play with.

    No I didn't waste $500 on a pack level charger. I did buy four modules (three of the weak ones I removed I sold) and one hobby charger so it cost me roughly $100 to prolong the life of the original pack by seven months while I still owned it. I never heard again from the guy who bought my Prius Dec 2016. He or his daughter might still be driving it with the original repaired pack.
     
    #16 jadziasman, Feb 19, 2018
    Last edited: Feb 19, 2018
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  17. kenoarto

    kenoarto Senior Member

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    I am absolutely heartbroken that the individual cell replacements haven't worked. At $5000, the car became a junker. At $1600-2000 it's an expensive, but worthwhile repair.


    Now let's define "fun"! Did you have to pull your battery and do repairs more than once during this 7 month period? And, how much time did you spend on each repair? Clearly (and wisely) you decided that you just couldn't trust the car with your failed patch jobs.
     
    #17 kenoarto, Feb 20, 2018
    Last edited: Feb 20, 2018
  18. Dxta

    Dxta Senior Member

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    Don't just replace only the modules in those blocks. I'd advice you replace the modules in the affected blocks all together. That would help cushion in the effect of having to go back doing the same job.

    I did replace the complete modules on blocks 10, and 11 in a Camry hybrid some weeks ago.

    All blocks were reading 16..volts, while block 10, gets to 20volts, and sometimes stays stagnant.

    Replacing all the block modules affected has fixed the problem.

    IMG_20180214_115115.jpg IMG_20180212_111133.jpg IMG_20180212_122253.jpg

    Pictures above were for the Camry hybrid. Same procedures for your Prius too.
     
  19. jadziasman

    jadziasman Prius owner emeritus

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    You seem to have an axe to grind. Bad personal experience with a pack repair that you're not telling us about?

    Fun because it was a new and novel experience. Fun because it was challenging. Fun because I succeeded on the first try.

    Yes, the battery was pulled because one module failed. I deemed three others weak. One repair only. The repair took three weeks - I didn't need to use the car at the time and my recent high school graduate daughter didn't need a car yet. I understand that not everyone has the luxury of having a spare car to take the time to do the repair correctly.

    The repair lasted seven months before I sold it and there were no signs that the repair was about to fail when I sold it. I didn't just slap in a replacement module and pray that it worked. I leaned heavily on the knowledge of the pioneers who made this repair and documented their adventures for which I am grateful.

    Part of my decision to unload it was that my daughter needed a reliable car to drive to campus and while at campus (she's a university student now). Instead of a buying new HV pack for the beater Prius, I purchased a nearly new 2015 Mitsubishi Mirage for her which has worked out well since December 2016.
     
    #19 jadziasman, Feb 20, 2018
    Last edited: Feb 20, 2018
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  20. kenoarto

    kenoarto Senior Member

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    Three weeks is a helluva long time to do a car repair!!! And the fact that you didn't trust your daughter driving it speaks volumes. These conversations are interesting and educational, but "fun" is the last word most people would use when doing car repairs. FWIW: my 2005 is still running quite well on the original HV battery, but I am watching and waiting...
     
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