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How I Recondition Cells

Discussion in 'Gen 2 Prius Main Forum' started by tracy ing, Jun 19, 2022.

  1. JohnPrius3005

    JohnPrius3005 Active Member

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    Amazing. To me it seems that positively identifying a bad module - as you have clearly - and accurately deducing the failure - a bad cell - is critical to building/reconditioning a working battery. To have a good battery you need good modules. To have good modules you need good cells. Hence those who sell modules claiming they are good simply because they have high voltage are at best guessing, or at worst completely deluding themselves and buyers. Hence the profusion of the whack a mole scenario in “reconditioned” batteries. This is why doing it scientifically - as you are - is the way to get practical results. Outstanding lessons for us all.
     
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  2. tracy ing

    tracy ing Active Member

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    That is why I never buy loose module unless all are from one prius, 28 modules, all the same date code and serial number series, they cant all be bad, I have only bought loose modules like that once, all the rest I sourced from cars in salvage and removed myself after checking they were factory modules in sequence.

    If I bought single loose modules I want 30 day money back with seller paying return shipping.
     
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  3. JohnPrius3005

    JohnPrius3005 Active Member

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    I’m sitting outside a junkyard in LA right now about to buy 4 Prius wheels and another HV bat from a 2014 wreck.

    If you were going to start checking an reconditioning cells afresh, today, if you have the time I would really appreciate a full list of equipment you would buy. I can deduce some of this from your posting, and I can see the only real way I’m going to have positive results with any modules I recondition is be doing exactly what you are doing.

    And do you have any of those “grid” chargers you mentioned that you are willing to sell? I made a few with Mean Well LED drivers and they work fine for what they are, and the charging current is so low that it doesn’t cause any excessive heating of the battery.

    Aloha. John
     
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  4. tracy ing

    tracy ing Active Member

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    I dont have anything for sale. As for equipment, well you need a meter, you need a way to charge and discharge.

    The device I use to charge, which can also discharge, but wont make any graphs, is about impossible to find anymore, i know, i just looked. Appears discontinued, so for a base charger solution, I would ask others here for suggestions, you should be able to set it for the following

    Charger
    For 6 cells, designed for NIMH and has end of charge detection that preferably you can set, eg 400 millivolts or whatever.
    Charge amps from 0.1 to 6.5 amps
    Limit it by TIME ( i never use that)
    Limit it by Amp Hours In (I use that all the time).
    Optional, limit by temp, i have that, i have never used it.

    The charger I use does NOT come with a required power supply, which they expect you to provide HOWEVER there is a plug in base designed specifically for it and impossible to find and if you do, we are talking 200 to 300 dollars for all of it, if you can find it.
    X1 PRO Multi Charger, although someone at a RC hobby place may have one on clearance you never know.

    If the charger can also discharge, then again, you would prefer 0.1 to 6.5 amps
    Graphing would be a plus


    For a solution to monitor and graph the charge, but not control the charge or provide charging that will also support discharging, and provide graphing, I use the West Mountain Radio CBA 2 which is old and has been replaced by a newer model, out of stock but supposedly inbound. CBA V - Computerized Battery Analyzer is the new one for 190 to 230 bucks, the extra money allows you to fine calibrate the unit (not needed unless you are really anal) and some sensing cable, dont know what that would be for, maybe temps, you would have to find out. The calibration is you check the battery with a meter and it says 7.102 and the cba 5 says it is 7.107. For 190 you cant fix that, for 230 you can.

    I think the chinese resistant tester is a good tool if you can drop 70 bucks, it can help you steer away from any obviously damaged modules before you waste time on them, all of mine test 6 to 7, i have a 9 and 10 and i wouldnt even mess with them now that i have the meter.

    YR1035+ is the model
    LeTkingok 4 Line YR1035 Battery Internal Resistance Test Meter

    As for my stuff that I have from years passed, it is a violation of Federal Law to sell anything that has been subject to a recall by the CPSC, thats why I have nothing to sell :)

    pro.jpg
    pro2.jpg
     
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  5. tracy ing

    tracy ing Active Member

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    If I has seen that 80 dollar combo I would have cleaned out all their inventory lol
     
  6. tracy ing

    tracy ing Active Member

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  7. JohnPrius3005

    JohnPrius3005 Active Member

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    Thanks Tracy, You are super generous giving me and everyone else reading this such a thorough education. Yeah, I've got into the habit of buying multiple units of things I like and use often or plan to use often. (right now this is mostly chainsaws, chainsaw chains and bars, and Prius HV bats!)

    I'll follow up on all your pointers. Likely I'll have a bunch of questions. Don't know that I'll get through the 5000 page book though ;-)
     
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  8. Prius92

    Prius92 Member

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    It's been interesting reading this, but I'm still waiting on some others to chime in as it seems the forum is split between discharging only to 6 volts and discharging deeper, to 3 volts.

    I will say this though...if discharging below 6 volts was harmful as even I initially expected, a high voltage battery pack would become a very expensive paperweight if the owner was called to a few years of military service or something else that caused the car to sit a couple years. There is a story of a Honda Insight that was in a barn for 15 years, and they were able to revive the battery back.

    If Toyota had batteries sitting in warehouses while GenII's and GenIII's were being built, I highly doubt they had each and every single one connected to chargers while waiting for cars, or spares for future replacements.

    Also, if you have a few modules that aren't any good from a 6v discharge/charge cycle, wouldn't it be better to try the 3 volt cycle a few times than tossing them?
     
  9. tracy ing

    tracy ing Active Member

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    In the end, Panasonic and industry, that have billions of dollars in this, say dont do it.

    As for deep self discharge, honda dealers were informed to start and charge the car using a defined process, i believe it referred to 3,000 rpm but i dont recall.

    As for prius, I am sure someone can chime in as to what toyota has directed them to do, the honda has a standard 12 volt starter as a backup, unlike the prius, and can start and charge the pack up.

    I tried the lower than 6 volt outlined by others and saw zero improvement in various cells of various condition, but all of those cells had already been subjected to some sort of recondition by me first. I never tested a virgin cell.

    The actual lower limit is under 1 volt, but I will say 1 volt, as I see no reason to go below it. When someone posts WHY and HOW this going below 1 volt does something beneficial ,then I will revisit it.

    With the global widespread adoption of the NIMH over two decades, if lower than 6 volt worked, it would be widespread knowledge, not voodoo magic in some internet posts here and there

    I am not aware that sitting even for years would cause a new in stock battery, or even a used one in good shape, to so deep discharge in voltage well below 6 volts.
     
    #49 tracy ing, Jul 25, 2022
    Last edited: Jul 25, 2022
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  10. Prius92

    Prius92 Member

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    BU-807: How to Restore Nickel-based Batteries - Battery University
    .

    Yes, the US army tests are for NiCd batteries, but NiMH batteries are of similar structure. It even states to keep the current low to prevent cell reversal, as others have mentioned before.

    Also that site says the army discharges airplane batteries, which are nickle based, to ZERO volts for 24 hours before recharging.

    The whole point is to break up crystal formation. The repeated charging to around 80% of SOC and discharging down to around 40% state of charge in the vehicle causes this to occur over time, leading to lost capacity.

    This is what I've been doing with great results, though it's on pause until a new discharger arrives.

    1. Fully charge the battery.
    2. Discharge the battery to 6 volts.
    3. Fully charge the battery again.
    4. Discharge to 6 volts at 10A. Record capacity.
    5. Discharge to 3 volts at C/10, or 650MAh.
    6. Charge at 5A to 8.6 volts, then reset charger to charge at 650MAh overnight (note, no swelling/heat will occur at this low of current).
    7. Discharge to 6 volts, note capacity again, and repeat the long discharge/charge cycle at least once, sometimes 4 times until capacity is at least 2,500MAh.

    As others have said, one lousy module will ruin the entire pack, because from what I understand the BMS see capacity of the 14 blocks, and will limit ALL of the blocks to the capacity of the lowest block. 2,500MAh isn't much, but understand we are working with modules that are up to 18 or so years old.

    Here are some numbers, first is capacity from one charge and discharge to 6 volts, 2nd is another, and third is down to 3, volts note the capacity improvement.

    Cell 2 2649 3144 4317 [Improvement] 495MAh 1173 MAh
    Cell 4 2155 2330 3898 175 MAh 1568 MAh

    You can see just how much more improvement there was going down to 3 volts..
     
  11. JohnPrius3005

    JohnPrius3005 Active Member

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    Interesting. I flew planes for many years. Our main concern with the NiCd bats was thermal runaway. Cost and loss of capacity was comparatively irrelevant although this might not be meaningful to this discussion.

    Would you mind posting details of the equipment you use to conduct your process? I’m very interested in developing an effective means of doing Prius bat reconditioning for my own vehicles. I really am learning a lot here.

    Also I’m very interested in knowing what equipment is best for graphing, and what equipment allows an accurate measure of capacity.

    Obviously there are some strongly held beliefs and understandings here but one method doesn’t necessarily invalidate the other. From my background I tend to strongly favor Tracy’s techniques since the manufacturer - Panasonic - and NiMH industry would seem to have the deepest insights. But I’ll also happily concede that results speak for themselves and Prius92 you are clearly pursuing interesting avenues and not just shooting in the dark.

    Again, thanks for the insights. Intelligent debate and testing of theories is most educational.

    Aloha. John
     
    #51 JohnPrius3005, Jul 26, 2022
    Last edited: Jul 26, 2022
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  12. tracy ing

    tracy ing Active Member

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    I have seen all that before
    There is no CADMIUM in a prius module
    All of that article refers to CADMIUM crystals and then interjects a lot of supposition to nimh.

    Breathing high levels of cadmium damages people's lungs and can cause death. Exposure to low levels of cadmium in air, food, water, and particularly in tobacco smoke over time may build up cadmium in the kidneys and cause kidney disease and fragile bones. Cadmium is considered a cancer-causing agent.

    There us no cadmium in prius cells
     
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  13. tracy ing

    tracy ing Active Member

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    intergranular corrosion of the coherent twin boundary is the issue NOT some phantom crystallization.

    Removal of them requires a 10,000 volt nano second pulse repeatedly, I have not figured out how to introduce that, as of yet.

    fyi that batt university site is full of bad info on all batt types

    “Pure nickel is mostly corrosion resistant. But when we charged it at the cathodic (passive and lowest energy) side, which is even less likely to corrode, we did, surprisingly, see visible corrosion trenches on coherent twin boundaries,” says Mengying Liu, graduate student at the department of materials science and engineering at Texas A&M University

    Coherent twin boundaries are areas in which the material’s internal structure pattern forms a mirror image of itself along a shared border. They occur when crystal formations on either side of an atom-wide border line up without disorder or disarray. These types of boundaries naturally occur during crystallization, but can also be the result of mechanical or thermal influence.

    For years, researchers have operated on the assumption that coherent twin boundaries resist corrosion. They have even worked to create metals that have more of these boundaries in an effort to reduce corrosion.

    “This finding takes decades of assumptions on metal corrosion and flips them on their head,”

    “In an effort to reduce corrosion, people have been making metals that contain as many coherent twin boundaries as possible. Now that entire strategy will have to be reconsidered.”

     
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  14. tracy ing

    tracy ing Active Member

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    Another issue is oxygen taken place in the HOLE in the nickel where the hydrogen is supposed to go, this can only be fixed by using high temps that would destroy the battery altogether.

    If crystals were an issue in NIMH there would be a ton of peer reviewed papers on the subject, post them here, I'll wait.
     
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  15. tracy ing

    tracy ing Active Member

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    Coherent twin boundaries are areas in which the material’s internal structure pattern forms a mirror image of itself along a shared border. They occur when crystal formations on either side of an atom-wide border line up without disorder or disarray. These types of boundaries naturally occur during crystallization, but can also be the result of mechanical or thermal influence.

    YOU HAVE TO REMOVE THE CRYSTALS BEFORE THE CORROSION, REMOVING THEM AFTER IS LIKE STOPPING SMOKING ONCE YOU HAVE CANCER
     
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  16. JohnPrius3005

    JohnPrius3005 Active Member

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    Tracy, you've clearly dug very, very deeply into this. Doing so has given you a strong understanding of the processes at work. And apparently your investigations and research continues. This is awesome. For someone like me - looking to get extra life out of degraded modules effectively - I can only be appreciative of what you do and hopefully use the result of your efforts to recondition my Prius modules realistically. As I've said, identifying failed modules and discarding them without wasting time trying in vain to recondition them, is extremely valuable. Reconditioning those modules that do not include failed cells in an effective manner is likely the only practical way to get further life from these batteries. I like your methods because they are clearly based on solid science rather than speculation, and I'll enthusiastically adopt those methods where I can. Much of the rest is very interesting also.

    Aloha. John
     
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  17. tracy ing

    tracy ing Active Member

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    This is from one of HUNDREDS of peer reviewed industry supported research papers, this one has 337 reference works footnotes by hundreds of other researchers

    Nowhere is CRYSTAL formation in NIMH an issue

    Find the paper about CRYSTALS where someone with a scanning electron microscope shows them in NIMH and also points to them as an issue with performance , I wont hold my breath



    upload_2022-7-26_9-55-37.png

    The word crystal shows up once in that paper

    The mechanism of reaction for Co in alkaline solution
    is rather complicated [ 38 ,221 ], but a simplified version for electrochemical engineers can be used as
    a guideline. Co in a +2 state is not a good conductor for electrons or protons, and it is only slightly
    soluble in 30% KOH. Co can be oxidized into the +3 state through solid-state reaction [ 222 ], and it is
    a good conductor for both electrons and protons due to the half-filled proton plane between two Co-O
    layers in the CoOOH crystal structure; however, the reaction is not easily reversible. The presence
    of Co4+ through a solid-state reaction can be detected at charge rates greater than C/5, and it can be
    reduced back to Co3+ at a potential of 1.05 V versus Cd-electrode [220 ]. There are three general methods
    for incorporating Co into the positive electrode of Ni/MH batteries, which leverage the irreversible
    oxidation of Co2+ in the normal operation voltage range (>0.63 V versus Cd-electrode [220 ]).
     
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  18. JohnPrius3005

    JohnPrius3005 Active Member

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    Yes, at some point repair becomes either impossible or not feasible, and replacement with new is the only practical way forward. "A man's gotta know his limitations" - Clint Eastwood as Harry Callahan ;-)
     
  19. tracy ing

    tracy ing Active Member

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    Common sense tells you the lower than 1 volt to remove crystals is a fantasy. There are no CRYSTAL REMOVAL chargers for NIMH on the market

    There are DESULFATING modes in chargers for lead batteries, why ? To get more money from the user because they can point to research that proves desulfation works

    There are CYCLING modes for NIMH chargers, mine has them, cause they can point to research, and get more money for a charger that has CYCLING.

    There are no crystal removing nimh chargers, cause its a myth, to produce such a mode or charger would lead to class action lawsuits lol.

    Common sense
     
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  20. tracy ing

    tracy ing Active Member

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    If I had used the charge algo I have used here, where I got 100% capacity back, and altered it, and taken the batteries down using the methods others promote to "get the capacity back" by going lower than 1 volt, then who was right, my algo ? or their algo incorporated into my algo lol

    You will never prove what they are telling you because they cant provide a baseline module (before after) to compare to another algo because their algo does the same thing but goes lower, possibly causing some type of long term damage, we dont know.

    If their algo is right, then I should be able to apply it to mine AFTER my algo, where the cell only makes 90%, and get some more back right ????

    I didnt, I lost a few percent, I tried it, my module was injured by the process
     
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