Mobile charger as Ni-MH charger

Discussion in 'General Electronics Chat' started by Arup, Apr 13, 2006.

  1. Arup

    Thread Starter New Member

    Apr 13, 2006
    3
    0
    Hi,
    I've a LG mobile phone fast desktop charger lying around with the following ratings
    input 12V, 0.3A
    output 4.2 V 0.5
    it has 3 pins at the output, the battery fits into a slot over it and has a bicolour LED for charge indication (red - charging, green - done)
    the circuit consists of 3 ICs
    K1A494AP - PWM controller
    LM358N - OP AMP
    GMS81C1102 - 8 bit CMOS microcontroller.

    My question is can this charger be used as a Ni-MH charger after modding the output voltage to 1.8/2.0 V.
    also what is the function of the third pin on the charger and the battery?

    Thanks and regards
    Arup
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,590
    777
    best answer is: maybe
    it depdends on the circuit.

    the third pin is usually connected to temperature sensor.
     
  3. paultwang

    Well-Known Member

    Mar 8, 2006
    80
    0

    A quick note: Your phone charger probably recharges a lithium ion battery. I am not sure if you can apply the Li-ion recharge pattern to NiMH batteries.
     
  4. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
    Thats pretty much the way I understand it as well. Not 100% on LIon charging, but I think is a constant voltage charge (4.2v per cell which would tie in with your figures) and Charge detection based on a drop off in current.
    NiMH however (like NiCads) use a constant CURRENT charge with detection using either a slight drop in cell voltage at full charge, or the rise in cell temperature. I believe NiMH also like a fast charge.
     
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