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Charging NiMh battery pack with BQ2004 - new thread

Discussion in 'Power Electronics' started by farukh037, Mar 13, 2018.

  1. farukh037

    farukh037

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    Mar 13, 2018
    Hi Anard,

    I am also sufferring from the same problem. i want to charge NiMH and Nicd battery of 9.8Ah and 4.4Ah respectively. Both are of 10 number of cells.
     
  2. farukh037

    farukh037

    11
    0
    Mar 13, 2018
    this issue comes when i select 12 cell by selecting RB1 as 200k and RB2 as 40K.
     
  3. farukh037

    farukh037

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    0
    Mar 13, 2018
    Dear Bobk,
    Hope you are good!

    i have seen that you have a great knowledge about the IC BQ2004. Kindly help me on the issue.

    Regards!
     
  4. farukh037

    farukh037

    11
    0
    Mar 13, 2018
    with no battery. I am selecting 10 cells by selecting RB1 as 200K and RB2 as 50K for my 10 cell NiMh Battery. i am using -delta voltage termination. current flowing is OK. but the termination is not constant.
     
  5. farukh037

    farukh037

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    0
    Mar 13, 2018
    I designed a battery charger with BQ2004H for 10 cells Nimh battery 10AH. I found the charger will always stop fast-charge before it's completely charged and the time seems shifts in the table in datasheet. For example, I set TM1 and TM2 as low/low, fast charge safety time should be 650min, but it always stopped/ terminate before the battery is fully charged. Anyone can give me an idea about it?

    a) Charge rate : C/8

    b)Termination: -ΔV method and C/8

    c) Auto discharge and Temperature termination are not using.
     
  6. farukh037

    farukh037

    11
    0
    Mar 13, 2018
    Dear Bobk,
    Thanks for your response.

    inductor with a value of 110uH of 3.9A is used with 10uF of Capacitor with ground. i am using these value with the reference to evaluation board of BQ2004E/H. Circuit diagram is attached here with.

    Regards.
     

    Attached Files:

  7. farukh037

    farukh037

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    Mar 13, 2018
    In evaluation board, 100uH inductor is using with 10uF capacitor. i think it is not a big difference.
     
  8. farukh037

    farukh037

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    Mar 13, 2018
    when disabling the voltage termination mode by connecting VSEL pin to GND or VSS, IC take complete time (650 min) to charge the battery pack. otherwise by leaving VSEL as floating (negative delta voltage termination) IC terminates the fast charge within 10-30 mins.
     
  9. BobK

    BobK

    7,645
    1,663
    Jan 5, 2010
    I think your charging rate is too slow for delta-V termination. This is normally used at C/2 to C charging rates.

    Bob
     
    farukh037 likes this.
  10. farukh037

    farukh037

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    0
    Mar 13, 2018
    Capacity of battery is 10 Ah. Should I charge it with 5A current for C/2 charge rate. I think its too much.
     
  11. BobK

    BobK

    7,645
    1,663
    Jan 5, 2010
    No, that is fine for a fast charge.

    Bob
     
  12. farukh037

    farukh037

    11
    0
    Mar 13, 2018
    Hi Guys,
    My problem of Early Termination is resolved. My charger is working perfect now. The problem was that i was using an unregulated VCC for charging IC, replacing this unregulated switching base IC with Linear regulator IC "L78L05" has resolve my issue.
     
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