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BQ35100: Some questions of Calibration error etc.

Motoyasu Hattori
Genius 10965 points
Part Number: BQ35100
Other Parts Discussed in Thread: EV2400, BQSTUDIO

Hi, My customer has some questions as follows: Could you please answer it?

*1.
He starts to evaluate BQ35100 with EV2400, but has not success calibration voltage yet, and following error is occurred.

「Calibration cell voltage entered is out of range. This value is in millivolts. Please check value and retry.」

Please let us know how to resolve this issue.
Software information is as follows:

bqstudio ver. 1.3.86
EV2400 ver.0.28
Bq35100 ver. 1.02 Build 10

 

*2.
Once he does ON/OFF power of BQ35100, GE(Enable)=High/Low, SOH(State-Of-Health) goes down every State of Health MAX Delta. Could you please let us know how to resolve this issue?

 

*3.
He plans to use Panasonic CR-AG, but there is no Panasonic CR-AG Version in Chemistry Programming model of BQSTUDIO. Could you please let us know how to make this model?

 

*4.
He plans to monitor primary batteries in SOH mode. Could you please let us know any materials to explain BQ35100 SOH in details?
He found the sentence on technical reference manual as follows, but he can not understand it.  So please advise us.

SOH = DOD(TermV) – DOD(OCV, temperature)
TermV is a DF constant determined by the manufacturer to be discharge voltage below which the cell cannot provide the power required by the device.

Thanks and best regards,
M.HATTORI.

  • 0
    TI__Mastermind 19195 points

    Hi Mtoyasu,

    1. What voltage are they applying? Can you upload the .gg here
    2. Could you upload logs showing this issue.
    3. If the cell is not found in the database then cells will need to be sent to TI for characterization.
    4. To explain the equation, if the ternV DOD is 80% and current DOD is 60% then SOH will be at 20%

  • 0 in reply to Nick Brylski
    Prodigy 80 points

    Hi, I am  MIZOBUCHI (I am one of Hattori-san's customers)

    I am sorry for taking a long time to have response.

    I will answer your questions instead of Hattori-san and have new questions.

    1. We were applying 2.8V. In this voltage, calibration error was occurred. But When applying 3.0V, calibration was successful. 

     Is this the reason why "BAT" pin and "REGIN" pin of BQ35100 EVB-795 are common ?  Is 2.8V low voltage for starting up BQ35100 ?

    2. This event has been resolved.

    3. We could not  find "CR-AG" in the database of the latest Chemistry ID. Who should we send "CR-AG" cell to for characterization ?

    to Hattori-san?, to you ?  We will use CR-AG as parallel connect (2 pieces), in this case, is it needed to send 2 pieces? 

    4. We understood your answer. One more question about this matter, how can we configure "the term V DOD" on GUI of BQSTUDIO ?

    5(new). When configuring parameters (Cell Design Capacity, Cell Design Voltage, Cell Terminate Voltage), SOH did not change. But when configuring Max Load, SOH changed. Is this phenomenon correct ?

    Thanks and best regards,

    K.MIZOBUCHI

  • 0 in reply to K.MIZOBUCHI
    TI__Mastermind 19195 points

    Hi,

    1:

    Here are the steps for voltage calibration:

    1. Enable Calibration Mode on the device by pressing the CAL_TOGGLE button on the Commands panel.
    2. Verify that the CalMode flag is set in the Control register.
    3. Set the Series Cell Count parameter on the Gas Gauging screen to the appropriate value.
    4. Reset the gauge using the RESET button on the Commands panel.
    5. Calibrate the stack voltage.

    Taken from here: https://www.ti.com/lit/ug/sluubh7/sluubh7.pdf

    3: I will reach out to your FAE, customers cannot submit chemID request on their own.

    4: You should configure 0x4204 Cell Terminate Voltage in DF

    5: Can you try sending  a reset command after adjust termV?

    Best regards,

    Nick

  • 0 in reply to Nick Brylski
    Prodigy 80 points

    Hi, 

    1. We were trying to calibrate  the voltage by the steps for voltage calibration you suggested. In case of voltage 2.9V and 3.0V, calibration was successful. But 2.8V was failed. Is there any limitation to configure the calibration voltage  ? We use the BQ35100 EVB-795.

    3. Thank you .  I think Hattori-san belongs to technical section of TI Japan. First, I will ask him.

    4.  this issue was resolved.

    5.  We are on checking it.

    6(new).  Can we use the gauge of BQ35100 with 2 Li-Mn02 cells in "parallel connection" ?  If it is possible, please tell us how to use. Is there any limitation to use ?

    Best regards,

    K.MIZOBUCHI

  • 0 in reply to K.MIZOBUCHI
    TI__Mastermind 19195 points

    Hi,

    1. The default value for Flash Update OK Voltage is 2800 mV, you may want to set it lower than this for updating at 2.8V.

    6.

    The gauge will work with two cells in parallel at the same time. This is why the gauge learns a scale factor. With two cells in parallel the impedance will be about half what it would be with one cell. With this method the gauge treats the pair as the cell. 

    The issue would come in if one of the cells gets replaced. The gauge has no way of knowing if one of the two is about to die. We cannot give an SOH for each cell, only the stack. 

    Best regards,

    Nick

  • 0 in reply to Nick Brylski
    Prodigy 80 points

    Hi,

    1. We configured "Flash Update OK Voltage" to 2.8V and below, but We could not calibrate at 2.8V and below. Are there any restrictions other than  "Flash Update OK Voltage" ?

    6. Do we need to configure any resisters of BQ35100 when we measure SOH by using two cells in parallel ?

    7(new).  Are "MAX Load" and SOH related ? Do we need to configure "MAX Load" to measure SOH  ?

    Best regard,

    K.MIZOBUCHI

  • 0 in reply to K.MIZOBUCHI
    TI__Guru** 105740 points

    Hello,

    Can you share a screenshot of bqStudio when you try to calibrate? The Glash Update OK voltage should be lower than any operating voltage of the gauge.

    No parameters need to be changed for 2 cells in parallel since it's voltage based correlation in SOH mode.

    Max Load does not need to be modified.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 80 points

    Hello,

    Thank you for your reply.

    ・Please see the attachment (screenshots of bqStudio)

    ・ I think your comment about Max Load is different from another comment （title: BQ35100: Programming Battery Chemistry）

    I would like to have your comment about title: BQ35100: Programming Battery Chemistry.

    ・One more thing, let me confirm about calculation for SOH in SOH mode.

    According to "5.2 SOH Mode in SLUUBH1",we can see the equation

    SOH = DOD(TermV) - DOD(OCV, temperature) for computing SOH.

    DOD(TermV) will be at Qmax. Qmax is Full chemical capacity.

    Is equation correct ?

    I think that equation bellow will be correct.

    SOH = DOD2(TermV) - DOD2(OCV-dV, temperature).

    dV = Ra x Max Load. Ra is internal resistance of cell.
    DOD2(TermV)is at FCC. FCC is usable capacity.

    If it is correct, Ra and Max Load are required to get SOH.
    I think Ra table is in Chem ID, Max Load is required to configure by manufacturer.

    Is this way of thinking uncorrect ?