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Battery charging behavior.

Discussion in 'Electronic Design' started by Boki, May 24, 2007.

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  1. Boki

    Boki Guest

    Hi All

    One of our wireless short range communication module, its charging
    behavior is:

    0~2.9V trickle charge. seems control by h/w

    3V~3.8V fast charge. should be initilized the fast charge by s/w.

    3.8V~4.2V trickle charge. must be controlled by s/w.

    Question, why need trickle charge at low voltage range.
    at 0~2.9V range, the charging LED will not turn on. Why need to turn
    off ?

    One more question, it seems after charging complete, there will be
    some current drawn, therefore the total voltage of battery will go
    down, when go down to a threshold it will recharging again.

    Any info I can study more ? thank you very much!

    Best regards,
  2. budgie

    budgie Guest

    If you are discussing Li-XX chemistry (the voltages sure sound that way) then
    the trickle below 3v is the standard way to bring the cell into the
    safe_to_charge_normally region. Current *has_to_be* very low when the cell is
    undervoltage, for safety reasons. Similar charge restraint is required when the
    cell is under-temperature.
    Depends how much current and where it is going.
    Again, if Li-XX then have a good read of the data sheet for a charge controller
    chip - such as the MAX1737.

    If not Lithium chemistry, ignore the above.
  3. Boki

    Boki Guest

    Yes, I am using Lithium battery, very useful, thanks!

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