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    NI-MH Battery charger circuit help

    Friends
    I need a charger circuit for 12x 1.2volt,2100Mah NI-MH Batteries .(14.4V)
    here what will the out put voltage and current for charging this 12 batteries ?
    which switching transformer for suitable this application ?
    Can you help?

    maxim10373

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  2. #2
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    Re: NI-MH Battery charger circuit help

    Hi,

    These are interesting, not sure if you've seen them. Both say NI-MH are prefereably charged at a C/10 rate.

    BU-408: Charging Nickel-metal-hydride
    NiMH Battery Charging Basics

    I think besides peer reviews of suitable ICs/switching supplies, it's good to go through manufacturers - such as TI, Analog, etc. - NIMH battery charger product parametric search lists and compare a few to see if any are ideal, if an IC is part of what you're looking for.

    I don't know much about this, but I'd guess you'd need something that can put out about half that capacity, so a 1 Amp supply would be ample, if at most it will only ever provide C/3.3 = 2.1/3.3 = ~0.64A (+ any housekeeping current used). And for C/10 = 0.21A minimum charging current required (+ any housekeeping current used).

    One of the links says at 20ºC, minimum charging voltage is 1.41V per cell = 16.92V for 12 cells in series.

    These seem quite complicated to charge and worth understanding the process and pitfalls well before starting.



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