Is it possible to achieve CC(Constant Current) using AX3112 to charge Li_Ion Batteries?!

Discussion in 'Power Electronics' started by gilsg7, Jul 11, 2016.

  1. gilsg7

    Thread Starter New Member

    Feb 26, 2016
    2
    0
    We are using AX3112 for Charging Lithium Ion Batteries and now we are facing a problem that we are not getting proper current. It is varying. Please suggest a solution. I have attached the datasheet of AX3112 and we have used the same reference design for four cells.
     
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,966
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    What current are you trying to get? What current(s) do you get? What was the battery voltage at the time? Schematic?
     
  3. BobTPH

    Active Member

    Jun 5, 2013
    785
    114
    Why not use one of the many LIIon charger chips instead? These handle the entire charging regimen, transistioning from constant current to constant voltage to top-off.

    Bob
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    It can be dangerous to charge Li ion batteries using a constant current.
    Suggest you follow Bob's advice and use a dedicated charger chip before you blow up a battery and burn the place down. :eek:
     
    RamaD, ci139 and #12 like this.
  5. gilsg7

    Thread Starter New Member

    Feb 26, 2016
    2
    0
    The charging current is 1Amps
    we are planning to use 4 lithium ion batteries in series.The battery should be charge in constant current and constant voltage.
    up to 4.1V the battery should be charge in CC (1Amps)and 4.1 to 4.2V in CV mode.
    we got the constant voltage but not the constant current.
    please help to figure it out
     
  6. BobTPH

    Active Member

    Jun 5, 2013
    785
    114
    If you plan to charge 4 cells in series, you need balancing cricuitry as well. Buy a commercial charger that does this right.

    Bob
     
  7. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,546
    1,252
    Constant current limiting as a way to protect a power supply output from an accidental overload, and a true constant current output for a specific application such as battery charging are two entirely different things. While the chip you are trying to use has a form of current limiting built in, it is not appropriate for battery charging and does not provide a constant output current when in current limiting mode. Again, it is the wrong part for the job and will not do what you want.

    ak
     
  8. Theevan Venugopal

    New Member

    Dec 30, 2015
    16
    3
    Thank you for your reply AK. Actually the problem is the IC can be used for the purpose of charging Li-Ion Batteries. We still have trouble to sort it out. Hope you may gone through the attachment of circuit in the above comments.
     
  9. ci139

    Member

    Jul 11, 2016
    341
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    ????????????????????????????????????????????? are you aware the(re's a) built in protection for some Li-Ion packages
     
  10. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,546
    1,252
    And you will continue to have troubles. Actually, the problem is that it is the wrong part for the job.

    The current sense transition level has a tolerance of +/-12%. That's a lot, and does not include the accuracy of the current sense resistor. To guarantee that the batteries' peak charging current is not exceeded, you have to decrease the design point by around 15%, and know that the actual charging current might be 30% below optimum. Not very efficient.

    Separate from that, you are assuming that the device will transition from CC mode to CV mode at a set output voltage value, but there is nothing in the chip to do that.

    "can be used" and *should* be used are not the same. Maybe you can beat it into submission, but it never will perform with the stability and safety of a part designed from the ground up to do this task.

    ak
     
  11. BobTPH

    Active Member

    Jun 5, 2013
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    I must admit that I did used a pair of pliers to pound in a nail once.

    Bob
     
  12. ci139

    Member

    Jul 11, 2016
    341
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    not enough power = (a) switch not closing fast enough e.g. device fault , overheating , poor contact (b) false frequency or/and duty (c) poor schottky
     
  13. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,966
    387
    too few electrons to complete the message?
     
  14. ci139

    Member

    Jul 11, 2016
    341
    38
    no i forgot to toggle the javascript back on (would allow finishing your msg. in real time . . . switching off the javascript while typing on a slow PC)
     
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