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  1. #1
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    Help modify Tpower 4211B based liion battery bank circuit

    hi
    i have bought a xiaomi battery bank 10400 mah but it is fake. one of its cell is filled with sand.
    others are of poor quality hardly 300-500mah each.

    i looked at circuit board. there is an ic from tpower tp4221B . this is smart ic for liion battery charging.

    i checked the cells voltage when it fully charged them .cells were charged to 4.2 volts then it stopped . charging current was 500 mah . input charger and its cable is fully capable of 2 ampere current (and tested as well ). so it means its charging at this little rate.

    now i have soem good liion batteries but they are to be charged at 4.35 volts not at 4.2..
    i looked at the ic specs it supports 1.3 Amp of charging current , 1 amp discharge, and supports both 4.2 and 4.35 volts chemistry liions.

    it has been a lot of time since i did electronics. please help me in finding achieve above two purposes.

    pictures of the circuit are uploaded .

    some refrence to the data sheet are given below.

    http://www.zjwic.com/upload/day_1412...1810438939.pdf
    http://shopper.life/diy-xiaomi-10400...l#comment13297

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  2. #2
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    Re: Help modify Tpower 4211B based liion battery bank circuit

    Quote Originally Posted by khankll View Post
    i have bought a xiaomi battery bank 10400 mah but it is fake. one of its cell is filled with sand.
    others are of poor quality hardly 300-500mah each.
    Hee, hee, haw, haw, ho, ho! Typical cheap Chinese garbage.

    some refrence to the data sheet are given below.
    The datasheet for the battery cell is written in Chinese. I do not know why they correctly say 4.2V but wrongly say 4.35V.
    A cell that is not charged to 4.2V has reduced capacity. Maybe these cells reach their "rated" capacity only when they are dangerously over-charged.



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    Re: Help modify Tpower 4211B based liion battery bank circuit

    Quote Originally Posted by Audioguru View Post
    Hee, hee, haw, haw, ho, ho! Typical cheap Chinese garbage.


    The datasheet for the battery cell is written in Chinese. I do not know why they correctly say 4.2V but wrongly say 4.35V.
    A cell that is not charged to 4.2V has reduced capacity. Maybe these cells reach their "rated" capacity only when they are dangerously over-charged.
    the batteries are good one .. and are being charged to 4.3 volts correctly using another charger..

    i need to modify this ic/board
    1: to charge at max or near max of its capability.
    2: charge till 4.3



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    Re: Help modify Tpower 4211B based liion battery bank circuit

    If you charge to 4.3V then most Lithium battery articles say the cell is over stressed and will not last long.



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    Re: Help modify Tpower 4211B based liion battery bank circuit

    no certain cells are rated for 4.3 volts. my nexus 5 charges to 4.318 volts then stops .. verified by multimeter as well as a software from play store ampere ..


    certain liion above 2600 require this ..



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    Re: Help modify Tpower 4211B based liion battery bank circuit

    Anybody can over-charge a lithium battery above 4.20V but it reduces its life.



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    Re: Help modify Tpower 4211B based liion battery bank circuit

    ^
    lets focus on the issues raised ..

    anyone who could read the data sheet ang give some clues to the solution to two issues indicated above?



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    Re: Help modify Tpower 4211B based liion battery bank circuit

    Try some things
    Check for connection between:
    VDD and SW - if have - put resistor divider at the BAT pin - it is input only, to simulate 4.2V from actual 4,3V; got me?
    VDD and BAT - if connection here, it is bad



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    Re: Help modify Tpower 4211B based liion battery bank circuit

    Quote Originally Posted by Tihomir Grozev View Post
    Try some things
    Check for connection between:
    VDD and SW - if have - put resistor divider at the BAT pin - it is input only, to simulate 4.2V from actual 4,3V; got me?
    VDD and BAT - if connection here, it is bad
    sorry i couldnt get you..
    the battery that i want to use wiht this is samsung icr18650-30a SDI (3000mah .. fully charged voltage 4.35 . fully discharged voltage 2.7 .. howver i am ok with this circuit discharging till 3 volts as its boost circuit output is not within usb limits at that volatge)

    i cannot decipher chinese datasheets of this product.. and couldnt find better then the two quoted in original post.



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