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BQ34Z100-G1: Full Charge Capacity update wrong

jiang liu
Intellectual 280 points
Part Number: BQ34Z100-G1

My pack is 6S1P .I get Chemistry ID from GPG ,DOD error less than 3%.
My steps as follow:
1、Set Chemistry ID
2、Set Qmax Cell 0 = 4000mAh
3、Set Number Of Series Cell = 6
4、Enable IT
5、Charge pack to full
6、Relax for more than 2 hours. Update Status =0x05
7、Discharge the pack to minimal device acceptable voltage at C/6.Update
Status =0x06 .Full Charge Capacity =True FCC= 3795 .
8 、Relax when VOK = 0 ,Full Charge Capacity and True FCC jump to 2572  ,True RC jump to  -1223 .

In my opinion , Full Charge Capacity may not current in
initialization,but after learning cycle Full Charge Capacity should
update .I don't  know why it return to 2572 when Relax.

  • 0
    TI__Mastermind 25955 points
    Hi Jiang,

    Gauging:

    If the chemID is proper (DOD error less than 3% should definitely qualify here), there may be a configuration issue. Please inspect your Data Memory configuration, especially the values for Design Capacity and Design Energy. Design Energy = (nominal single cell voltage) * (design capacity in mAh)

    Hardware:

    Please check your hardware connection to the battery and ensure it is solid.

    If these steps do not resolve your issue, please send the SREC from your device and the log of the test described above.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Intellectual 280 points

    I set Design Capacity = 4000mAh and Energy. Design Energy = 3.7*4000 .

    Yesterday and today ,I did three tests and all are unsuccessful . First I Program a new image file from   and set Rest .

    Then I follow  the steps form 1 to 6 above .

    After charging to full  CHG = 0 , FC= 1 ,but when VOK = 0 ,  Update Status =0x04 .Qmax learning is unsuccessful . The common performance is DOD0 = 0 and Qmax DOD0 = 0 when VOK = 0 . Is it reason of learning unsuccessful? 

    Other than this ,I have other questions .

    1、I find  after voltage calibration  Flash Update OK Cell Volt unequal to  2800 × Number Of Series Cells × 5000/Voltage Divider  ,so I set  Flash Update OK Cell Volt =2241 which is equal to 2800 × Number Of Series Cells × 5000/Voltage Divider. Is it right?

    2、I can no find Quit Relax Time at DF?

    3、 In my GPC_report.txt ,It said "Warning: Max R deviation ratio can not be checked because discharge hr-rate is above 12.  Hr rate = 13.9781325346597" . Discharge at 0.5A , how to Calculation hr-rate ? 

  • 0 in reply to jiang liu
    TI__Mastermind 25955 points
    Hi Jiang Liu,

    Yes, the learning was unsuccessful. The points were not qualified.

    1. This value should work for LFP or Li-ion
    2. This parameter is not accessible, but has been included in the datasheet for completeness
    3. Please ensure your discharge rate is C/10.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Intellectual 280 points

    About my first question of True RC jumping to -1223 ,it maybe because the initial value of True RC is negative and the initial value of True FCC is 1000mAh less than Qmax.Can you tell me what the initial value of True FCC related to? I find the initial value of True FCC is different when IT ENABLE using same Design Capacity.
    About my second question of DOD = 0 at step of 6 that make Qmax updating failed ,today I increase Taper Current to 1000 that make getting Charge Termination earlier.It Seems to solve the problem but I don't know why.
    Other than this I have some question.
    1、after IT ENABLE ,VOK= 1 , DOD0 = Qmax DOD0,wating a while VOK = 0 ,OCVTAKEN = 1 , Qmax DOD0 update. My question is after IT ENABLE whether need to wait a while until VOK = 0 though pack is relaxed.
    2、when Update Status = 6 ,Qmax = 3930 and Remaining Capacity = 55 which are right for my pack ,but Full Charge Capacity = 3671 that is less than Qmax.Is it right?
    3、when Update Status = 6 , Ra Table is 0055 and Ra0x Table is ffff which is not update ,Is it right ?
    4、When discharging the Grid Number is less than 4 ,Ra Table 5 is update ,It seems different of SLUA450 about Update of Resistance."Resistance is updated in the Data Flash (in DF.Ra Table) after each 11.1% of DOD charge is exceeded".Can you tell me how is this going?
    Below are sres and log of today.6404.Data.zip

  • 0 in reply to jiang liu
    TI__Mastermind 25955 points
    Hi Jiang Liu,

    I will analyze the data and provide an update on Tuesday or earlier.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    TI__Mastermind 25955 points
    Hi Jiang Liu,

    1. Setting Taper Current = 1000 mA basically forces the gauge to set FC whenever the voltage is greater than Charging Voltage for 2 consecutive 40s windows (default). This could cause your device to set FC prematurely.
    2. FCC is usually less than qMax. qMax is ideal and maximal. No load. No taper current.
    3. This is correct. The gauge is using the learned table. The next time the gauge learns (updates), it will update the 0xffff table.
    4. For Cell0 R_aM where:
    If 0 ≤ M ≤ 8: The data is the resistance normalized at 0° for: SOC = 100% – (M × 10%)
    2. If 9 ≤ M ≤ 14 : The data is the resistance normalized at 0° for: SOC = 100% – [80% + (M – 8) ×
    3.3%]

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Intellectual 280 points

    Thank you for your reply.

    In my test ,Qmax is Closer to the true capacity = 4000 ，but Full Charge Capacity is 12% less than true capacity. I don,t know why Full Charge Capacity is smaller and smaller .After last discharge(discharging at C/5) , Full Charge capacity = 3673 ,voltage = 20190 , DOD = 15848 ,Remaining Capacity = 54 ,but after this discharge(discharging at 1.3C), Full Charge Capacity = 3499 , voltage = 20778 ,DOD = 15542 ,Remain Capacity = 0 ,True Capacity  = -41 .Is there any possible season about Full Charge Capacity getting smaller ?

  • 0 in reply to jiang liu
    Intellectual 280 points
    In addition, there is another phenomenon，after discharging at 1.3C，when VOK = 0 , Remaining Capacity = 99 .But waiting for server hours ,I
    found Remaining Capacity change to 0 .
  • 0 in reply to jiang liu
    Intellectual 280 points

    There are some other question:


    1、At the end of charge or discharge ,Full Charge Capacity 、Remaining  Capacity 、True FCC jump down.Waiting for VOK=0 ，they are back to normal.Why those value jump?

    2、 In my tests ,the time from the end of charge or discharge to VOK=0 is aways several minutes,Is it normal? 

    3、after VOK = 0 ,value of capacity 、QmaxDOD and so on also change over time .Is it normal?

  • 0 in reply to jiang liu
    TI__Mastermind 25955 points
    Hi Jiang Liu,

    1. RemainingCapacity() and FullChargeCapacity() will change depending on the present load and temperature. These shifts are occurring after very different loads are being applied (0.5C vs 1.3C). In more detail:

    The bq34z100-G1 acquires and updates the battery-impedance profile during normal battery usage. It uses this profile, along with SOC and the Qmax value, to determine FullChargeCapacity() and StateOfCharge() specifically for the present load and temperature. FullChargeCapacity() is reported as capacity available from a fully charged battery under the present load and temperature until Voltage() reaches the Terminate Voltage. NominalAvailableCapacity() and FullAvailableCapacity() are the uncompensated (no or light load) versions of RemainingCapacity() and FullChargeCapacity(), respectively.

    2. Yes, this value takes time to set. Of note, QmaxDOD0() is only valid when VOK is asserted.

    3. Yes, these values change over time. QmaxPassedQ returns the passed capacity since the last Qmax DOD update whereas DOD0() will return the depth of discharge during the most recent OCV reading.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Intellectual 280 points

    Thank you for your reply.
    I still have doubts about capacity.
    1、As you said FullChargeCapacity() depends on the present load and temperature.In my
    test current = 0 temperatur = 30°C after charging and VOK = 0 .Current is zero can be
    understand as light load? Why FullChargeCapacity is 12% less than Qmax ?
    2、In SLUA450 ,Qstart = 0 for a fully charged battery .In my test because True FCC is
    small ,after fully charging ,True RC >True FCC,Qstart = -241 . How should I understand
    this phenomenon?
    3、There are my tests log and srec.The phenomenon during a discharge is True RC jump to
    298 to 22,and Remaining Capacity Reduce slowdown .Why is it going on?During discharge
    which capacity can I trust?8816.Data.zip

  • 0 in reply to jiang liu
    TI__Mastermind 25955 points
    Hi Jiang Liu,

    You will receive less capacity with a heavier load.

    Depending on the load mode, the FullChargeCapacity() will depend on the present load. The values from the present load are saved in Avg I Last Run and/or Avg P Last Run.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    TI__Mastermind 25955 points
    Hi Jiang Liu,

    Haven't heard back since this answer was suggested - hope the issue is resolved. If not, please let us know.

    If this answer resolved the issue, please hit the green 'resolved' button to help improve question/answer searchability on the forums. Thank you!

    Sincerely,
    Bryan Kahler