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Thread: NiMH battery packs with balancing port

  1. #1

    Default NiMH battery packs with balancing port

    I didn't conduct extensive search just short one on large online market place. What I could see there is as well as no battery pack built from NiMH cells geared with port for balancing. This might be reason why none of balancers of my interest has program for balancing nimh packs. I wonder where could be the root-case of this situation, would for instance the price of pack increase by factor 2 upon adding balance port? I doubt cells will never run out of balance in NiMH battery pack.

  2. #2

    Default Re: NiMH battery packs with balancing port

    The problem with NiMh batteries is that the state of charge "full" cannot be determined on the basis of the single-cell open circuit voltage or with a specific end-of-charge voltage as with a LiIo battery. That should be the main reason why there are no NiMh battery packs with balancer connection.

    If the NiMh batteries were equipped with balancer connections, the control of the chargers would have to be adapted extensively.

    A separate individual cell evaluation of the delta peak of each individual cell would be theoretically conceivable. As soon as a cell was recognized as full, almost the full charging current would have to be discharged at this cell.

    Another approach would be to generally only charge such batteries with single chargers connected in series only via the balancer connections.

    In both cases, a considerable additional effort for the charging equipment.
    A further development of the chargers in this direction is no longer to be expected from the charger manufacturers because of the generally diminishing importance of NiMh battery packs.
    Last edited by sbj; 06-01-2020 at 12:51 PM.

  3. #3
    *Flashaholic* HKJ's Avatar
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    Default Re: NiMH battery packs with balancing port

    Quote Originally Posted by Oiyuk Ti View Post
    I didn't conduct extensive search just short one on large online market place. What I could see there is as well as no battery pack built from NiMH cells geared with port for balancing. This might be reason why none of balancers of my interest has program for balancing nimh packs. I wonder where could be the root-case of this situation, would for instance the price of pack increase by factor 2 upon adding balance port? I doubt cells will never run out of balance in NiMH battery pack.

    The balancing is done by slowly charging the cell, any extra charge will then be converted to heat.
    The standard 16 hour NiMH charging can do that, but it is also possible to do a fast charge followed by a top-off charge.
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  4. #4
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    Default Re: NiMH battery packs with balancing port

    Prior to the introduction of low self discharge NiMH, balancing the cells in a pack really wasn't a concern.

    The self discharge aspect in some ways helped to balance these packs out.

    I am certainly not an expert in this area, but I was faced with a similar problem on a 4S cell NiMH AA pack recently.

    My simplistic conclusion was that LSD cells sort of force individual cell charging, which I didn't want to do.

    The path that I went down instead was to use a non LSD cell type in the pack.

    This was my conclusion after reading a lot of on line info, as well as info from HKJ and AACycler web sites.

    My goal was somewhat simplistic though - I am happy enough with 100 cycles and tossing them.
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