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The Good, The Bad & The Weak HV Module

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Danny Gonzales, Feb 9, 2015.

  1. Danny Gonzales

    Danny Gonzales New Member

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    Well , it’s my turn to face the “Triangle of Death” on my 2007 Prius with 174,000 miles. But I was in a hurry to get it fixed, so after several online searching, I decided to opt for a reman module pack with 1 year unlimited warranty with mobile installation. The engineer came from Orange County, CA to the Bay Area and I was happy with his service before and after the install.

    However, my curiosity has started and has to be satisfied because I want to take control the next time it happens. I have read, reread and reread again the post on “Gen II Individual Battery Replacement” started by “ryousideways” last April 13, 2013.
    For a start, I have ordered 4 Gen II module packs on ebay whose seller claims static voltage of 7.3V each. Plan on ordering the Hitec X4 or the DC6 chargers along with Techstream and mini VCI.

    I have some questions that I need help with:

    First clue of a faulty module is in the Static Voltage measurement result of the 28 modules which I read is usually the distinctly low readings. Actual measurements below:

    7.61
    7.6
    7.61
    7.6
    6.2<----low
    7.6
    7.6
    7.29<----low
    7.61
    7.59
    7.62

    Question 1: After the balancing the module packs, how would I characterize a faulty module against a weak module with regard to charging and discharging characteristics?
    [​IMG]

    The low static V above showing a reading of 6.12V showed the above discharge/charge characteristics.


    Question 2: Is this module still good after attaining the required charging capacity?

    This one showed a static V reading of 7.61V but after balancing process showed the below characteristics:
    [​IMG]


    Question 3: Is he The Weak and I better replace him. I notice also at the 2nd and 3rd discharge that they differ only 26.6mAh plus a low final charge of 6961 mAh.

    Below chart is definitely “The Good”.
    [​IMG]


    Your comments are greatly appreciated.

    Danny G

    Had to learn uploading charts so did a lot of editing.
     
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  2. nh7o

    nh7o Off grid since 1980

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    Thanks for those graphs. Are those voltages that you observe, in the list of modules, taken from your reman battery? If so, that is not a good sign. Maybe they were from the original battery.

    After cycling the low 6.2V module, what is the resting voltage now? Did it change? If not, then maybe a few more cycles might shift it a bit? This is an experimental field, so all the data points help.

    I think the main thing I have seen from the DIY balancing posts, is that if there is much divergence in a given module characteristic from the norm, it is best to replace. It will probably need replacement down the road, sooner rather than later.

    The one thing that is not being well measured in these balancing cycles is the internal resistance of the module at high current. One way to do that is installed in the car, using the mini VCI. Otherwise, one needs more specialized instrumentation.

    It is the internal resistance that makes for excessive heat in a pack, which is a detriment to adjacent modules. It is possible for a cell to have decent capacity, but a borderline high internal resistance.
     
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  3. Danny Gonzales

    Danny Gonzales New Member

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    nh70,

    I thought plotting the behavior in excel shows a more graphical presentation of what's happening. The REMAN is still doing well after 500 miles and those voltages were from other posts. I am just trying to get a good understanding of the behavior of the BAD and the WEAK compared to the GOOD module.

    I am going full blast on this so I have ordered 4 Gen II modules, a Thunder T6 Quad charger and a mini VCI cable. Down the road, I'm also looking for a whole Gen II Hybrid battery pack and another set of quad charger. I want to setup my own charging system and take personal control of the situation when the Triangle of Death shows up again :). Besides, I promised my granddaughter a car when she goes to College, so a Prius would be my best choice.

    I'll try measuring the Module Resistance as well when I get started with my setup. For sure, I'll have more questions when I get goin.

    Why are you saying "It will probably need replacement down the road, sooner rather than later". Is the car exhibiting any abnormalities or change from the norm now? Not hoping for it but just in case, please post what you observed prior to it happening.

    On my 07 Prius, it showed up all of a sudden with 2 bars left on the gas. After 2 days, I filled her up and to my surprise, the Triangle of Death disappeared. It took about 5 days, then it showed up again. Then my gas mileage dropped from 47 to 37 mpg. It would also rev up and won't pull normal. I found out that when I shut it down, then it would go back to normal. Had it diagnosed and was told Module 10 was weak. I was also quoted $4k to get it fixed with a new Gen II battery. Did a lot of research on how to get it fixed fast and I opted to an Electrical Engr from Orange County who quoted me $750 with 1 year warranty unlimited mileage. I chose him because he's the one that best explained to me how the reman was done. He also had 12 Priuses in the family one of which has 410k miles on it already. He speaks it and lives it too.

    I'll post later a summary of what I have learned so far with the hope that others may benefit from it as we have benefited from others that experienced the problem before us. Love this website.

    Aloha! I love your yellow fin tuna.

    Danny
     
  4. bisco

    bisco cookie crumbler

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    the exact amount of acceptable deviation from one module to the next is unknown. and static measurements are only helpful in locating the current bad cells, not the ones that will be going in the near future. that's why nh7o recommends the vci for testing under load. keep this in mind, you have an 8 year old battery, all the cells are going south sooner or later, kinda like you and me.:cool:
     
  5. Danny Gonzales

    Danny Gonzales New Member

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    10-4 although I'm still in denial.
     
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  6. Danny Gonzales

    Danny Gonzales New Member

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    Joking aside, does this mean that it's "The Good and The Bad" only during the test/balancing stage? And the WEAK, I can only tell through nh70's recommendation?
     
  7. Danny Gonzales

    Danny Gonzales New Member

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    Here u go! First draft of the Balancing Procedure I have summarized from previous posts here. Thanks a million to the PC gurus that have made my preparation/study a lot easier.

    Legend:
    VaB: voltage after balancing
    VaP: voltage after Parallel all modules

    I need to insert Module Series Resistance (per nh70 and bisco's inputs) and Static Voltage (first measurement) along with other incoming inputs readers will suggest.
    Balancing Procedure.png
     
  8. bisco

    bisco cookie crumbler

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    i think that's it exactly, but i'm only going by what i think i've read in the past. a lot of people change out the bad, balance and get 3 months or more, rinse and repeat.
     
  9. nh7o

    nh7o Off grid since 1980

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    The Prius modules have a remarkable level of manufacturing consistency, which means that they will tend to have a narrow range of lifespan, other things being equal. People end up playing whack-a-mole if they only replace just the one module that has caused the DTC in the pack, as another DTC will probably appear before long. How well that works for anyone depends on how much they enjoy the process of module replacement.

    That is why it is probably best to have a high standard for what modules are kept in the pack, and what is discarded. As the grid charger based balancing method becomes more tested, I think it may prove to be better than the system people are using now. Using the mini VCI to keeping tabs on module spread and internal resistance while driving, and balancing the pack as a whole in place, should point out the modules which are failing without removing them from the pack for testing.
     
  10. Danny Gonzales

    Danny Gonzales New Member

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    Thanks bisco & nh70.
    For now, I'm enjoying the learning process but I don't want repeated process of module replacement. I may go through 2-3 times while learning but won't be enjoying it after that as it is not fixing the problem. Looking forward to the Grid Charger based balancing method when it matures.

    Have yet to learn the use of the mini VCI when my order comes in.

    Thanks again guys.
     
  11. CrazyLee

    CrazyLee Member

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    It looks like a lot of bother and time spent trying to get your battery in good condition. Then it seems that you may suffer later battery pack failures down the road. I like the idea of the Grid Charger by keeping the battery balanced.

    If it takes a month to refurbish the battery then it takes way too long. Besides your wife may complain "If you say one more thing about your battery I'm going home to Mother!"

    I am of the opinion that a NEW battery from Toyota is in order. Sure it costs more, but the results are much better with a generous warranty.

    Even resale value is much better.
     
  12. Britprius

    Britprius Senior Member

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    The Toyota guarantee for the battery is far from generous at only one year. While at leased one re builder is guaranteeing there battery for three years.

    John (Britprius)
     
  13. robinredd1

    robinredd1 Junior Member

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  14. mr_guy_mann

    mr_guy_mann Senior Member

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    So, the module that was at 6.2V is bad, replace it. A voltage reading of 1.0 to 1.5V lower than all others is pretty much diagnostic of a failed cell. It will likely drop out when heavily loaded.

    The others could be fine after discharge - charge cycling. Some people just go with what they have based on the discharge capacity. Others will load test the modules with 5, 10, or more amps.

    What they do is to record the module voltage then apply a bigger load (say one or two 12V halogen headlight bulbs) for a fixed time (maybe 30 seconds) and note the voltage just before turning off the load. They look for similar drop.

    Posted via the PriusChat mobile app.