Hybrid battery reconditioning

Discussion in 'Gen 2 Prius Technical Discussion' started by Four1Seven, Aug 16, 2020.

  1. Four1Seven

    Four1Seven Junior Member

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    Hello I’m trying to charge/discharge/recondition a 2007 Gen 2 hybrid battery. What is the best setting for the charger to use? Amp, Max, Min, times, etc? I planned on doing it 3-5 times and then balancing them all when they are all full by connecting them all together in parallel and letting them equalize out. Any tips would be greatly appreciated.

    Thanks guys!

    Ty
     

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  2. edthefox5

    edthefox5 Senior Member

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    all while battery is still in the car? You removed the harness while the battery is still in the car wow that’s lot of crouching and work.
    So much easier with the box out,

    Balancing is done with them in series while doing a full pack charge.
    Just connecting them in parallel does nothing there already connected in series,
     
    #2 edthefox5, Aug 17, 2020
    Last edited: Aug 17, 2020
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  3. jamber

    jamber Junior Member

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    I'm also in the process of doing my first reconditioning on a 2006 that has already had one rebuild before. Ridiculously high learning curve this is. Thankfully there's over a decade of posts here which can take far too long to go through.

    This post from 2013 gives a pretty good answer to your question about the settings and explains the final steps for equalizing/balancing the batteries well. I've changed the charging settings a bit for my setup which I'll explain.

    Charge at 2 amps up to 7250mAhr
    Discharge at 0.7 amps down to 6 volts
    DSCH<CHG for 3 cycles.
    Other settings: I set the timer limit to 720 minute cut off. I also set the cool down period to 10 minutes.

    I first extended the cooldown period to be longer to be safer, allow the voltages to normalize better, plus I live in a hot climate. More importantly I lowered the charge rate from 5 amps to 2 amps. Many others have had no issue with 5 amps, but others including myself found better results from a slower rate. This is due to Peukerts Law which says that you can get more potential energy if you don't draw it all at once. I like to think of it similar to weight lifting; you get better results (conditioning) from a steady pace with a good weight rather than simply pumping all the energy into a couple reps with super heavy weights.

    Here's a thread where I originally learned about the law and a good post about why lower amperage is better:
    Here's a graph demonstrating the Peukert effect in Panasonic nickel-metal hydride batteries I found on Google.
    [​IMG]

    By reducing the energy going into the cell you reduce the heat energy produced and bubbling. When it bubbles that means the material is deteriorating which is not good if over-done. When charging the cell doesn't produce much heat until it gets to capacity then it will inflate from the hydrogen expanding. When discharging the cell produces heat at a steady pace. Don't let it get over 43 c and also only balance with it clamped in the pack or on a vise. A couple fans is necessary.

    When discharging this is when you get the mah reading that shows how much energy is in the cell, which is what we are trying to increase. Do not charge below 6v or you'll risk damaging the cell. There are 6 batteries inside each cell, which is why this is said. I found some people even saying to not charge below 6.2v, but my charger doesn't do tenths.

    The bulk of the conditioning happens when you are topping off the battery. I'm currently at 7250 mah but I'm considering going higher to 7500 mah. I've found other threads where they produced even better results from doing this, though I'm a bit concerned about doing this to cells that are over a decade old. I've watched my cells get pretty fat at 7250 however it is less fat than original charges done to them at 5amps, and maybe the few cycles that they have already been through would allow them to handle a fourth cycle at a higher capacity.

    I only have one balancer (definitely getting another asap) which is an HTRC that doesn't have computer connecting features, which is something I wanna do because I like data analytics. The IMAX B6, which is what you got, has that feature. I've got that one bookmarked to buy.
     
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  4. sam spade 2

    sam spade 2 Senior Member

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    None of the "reconditioners" can really reclaim a failed battery.....although some will claim otherwise.
    Regardless of what procedure you use, it might not gain you much on a 13 year old battery.

    THEN.....connecting a bunch of cells in parallel when their individual condition is not known is a BAD idea.
    If one of them fails in such a manner that it shorts out, all of the others will pump a HUGE spike of current through IT......and an explosion or fire might result.
     
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  5. Four1Seven

    Four1Seven Junior Member

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    Thank you so much for all the information. My problem now is the charger doesn’t seem to stop at the maximum set of 7250mah. It keeps going deep into the 8’s before discharging. Is my charger messed up or what do you think is causing this? Also how do you recommend balancing them? How do I know it’s time to do that?

     
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  6. edthefox5

    edthefox5 Senior Member

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    Has to be balanced as a pack which requires a 240 volt charger at a very low fixed current.

    hybridautomotive.com
     
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  7. jamber

    jamber Junior Member

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    I'm not completely sure how to set it properly without one in front of me, but from what I understand from reading the manual online the charger is automatically calculating how much energy is in it based on the Delta V setting.

    From a couple searches I'm finding people are just adjusting the IMAX B6 until it "works" for them, which doesn't seem right to me. Please report what you figure out.

    My charger doesn't have a delta-v limiter on it only a time, voltage, and mah limiter. I just finished the first charge with a 7500 mah limit @ 9 v limit on a cell that hasn't been cycled yet. It stopped before 7500 on 7363 mah @ 8.44v . Which is good and means that it reached full potential capacity. I didn't see any swelling so I believe that the slower rate of charge is what made it acceptable. Also I read somewhere that the max voltage you'd want to put on a NiMH cell is 1.45 x 6 = 8.7 volts.
     
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  8. sam spade 2

    sam spade 2 Senior Member

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    Which will give you a pseudo-balance.
    A proper balance must be done one cell at a time........or in parallel with a fuse for each cell.
     
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  9. valsor

    valsor Junior Member

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    You can't really balance a cell inside a Prius module which is sealed. What I learned is that all you need is to form-charge a module for 4 hours after charging it to capacity, then all 6 cells inside will balance by itself.
     
  10. jamber

    jamber Junior Member

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    Could you elaborate what form-charging is?
     
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  11. dolj

    dolj Senior Member

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    He just did:
    or to slightly expand that statement:

    All you need is to form-charge a module; that is, you need to charge it for 4 hours after charging it to capacity, then all six cells inside will be balanced, more specifically top-balanced. Quite simply a top-balanced module is one where each individual cell contained within the module will be fully charged. In order to do this safely, you need to charge at 0.05C, which for a 6.5 Ah Prius module is 325 mA and it is highly recommended that cooling of the charging modules is applied during the charge.

    Normally a forming-charge is the first charge applied to a new battery in order to ensure it is fully charged and top-balanced before being placed in service.
     
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  12. C Wagner

    C Wagner Member

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