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BQ27Z561-R2: Implementing the learning cycle using the BQ27Z561 fuel gauge IC.

Aachal Patel
Prodigy 10 points
Part Number: BQ27Z561-R2
Other Parts Discussed in Thread: BQ27Z561, GPCCHEM, BQSTUDIO

Tool/software:

Hi,

I am implementing the learning cycle using the BQ27Z561 fuel gauge IC on an LP353035 LiPo battery (3.7V, 400mAh). I have completed the learning cycle up to step 3 (discharging process), and the update status has progressed to 05. However, it should update to 06 after the discharging process, but it has not. Can you help identify the possible reason for this issue?

The Chem-ID I am using, according to the GPC report, is 1123, and the max DOD % is 2.5. Additionally, the Ra table gets updated after the charging process.

GPCPackaged-report 1.zipLog05-06.zip

  • 0
    TI__Intellectual 2020 points

    Hello Aachal,

    Based on your gg file, it looks like your Ra table hasn't updated. Note that update status changes to 06 after the second Qmax update during relaxation. You can try relaxing the battery longer to see if there is a change in Update Status as well as the Ra table.

    After going over your log file, it looks like the R_DIS bit is being set during discharge. This could be due to a ChemID mismatch. Could you send us your srec file and the files you submitted to the GPCCHEM tool?

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Yes Sure,
    Below is the attached file I have submitted to GPCCHEM tool.

    GPC_Files.zip0525.GPCPackaged-report 1.zip

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    The charge rate on the report you sent is too high (3C while the recommended rate is about C/2). You can try charging at a much lower rate to 4.2v and discharge to 2.75V at CV instead of 3V. You can submit another report to GPCCHEM tool after making the necessary changes.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    I have completed my Learning Cycle, and now, while testing the Golden Image with the custom board, I am experiencing sudden jumps whenever the battery gets fully discharged or fully charged. The jumps are occurring only with the custom board and not with the EVK. Even, the full charge capacity of the battery is also reducing every time a charging/discharging happens.

    Can you suggest something over this? I am unable to determine the exact reason for these jumps and the decrease in the battery capacity. Additionally, during the Ra table update, only Ra_0 was updated, and not R_a0x. Should both tables be updated for a successful implementation of the learning cycle?

    I am attaching the Golden file and the log files for both charging and discharging for your reference. Please review them and let me know what might be causing this issue.

    17-06GoldenImage 1.zip8686.Log Files.zip

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    Can you send us a bqStudios Log file, the gg files you used in bqStudio and schematics for your custom board? The attached log files seem to be of a different file format.

    Both tables should update successfully.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hello,

    I have log files from testing this with the custom board, where the EVM was not connected. The generated golden file works properly on the EVM.

     Below is the attached schematic of the custom board.

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    Are these log files from bqStudio? The one you sent us in your previous reply seemed to be a custom format.

    Your schematic seems alright.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    No the log files that I sent in previous reply were custom format.

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    We need a bqStudios log file to debug your problem. We won't be able to use a custom log file. You can use the Start Log function in bqStudio to get a bqStudio log file.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    I am attaching the logs of the custom board with bqStudio as you mentioned.

    The golden image I generated was tested with the EVK using a constant current load and it worked properly. However, when I tested the same golden image with the custom board, I noticed jumps at the end of the discharge process. I observed that to discharge the battery, we were powering up all the modules, resulting in an inconsistent discharge current. Therefore, I changed the load mode from zero to one. Unfortunately, I am still experiencing jumps at the end of discharging.

    I am also attaching the files containing the fuel gauge parameters for your analysis. Please review them and let me know if any other configuration parameters need to be changed.

    28-06_bqstudioDichg.csvdataMemory_Parameters.gg.csv

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    I checked your gg file. Does your pack have a 3s configuration. Your design voltage is set to 4.25V. Design voltage must be set to the # of cells in series * nominal voltage of each cell.

    I also noticed a potential ChemID mismatch, so I would suggest running a new cycle and get a GPCCHEM report. 

    https://www.ti.com/lit/an/slva725a/slva725a.pdf

    Please follow the steps outlined in this document.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    1. Can you explain what a 3s configuration is?

    2. I have confirmed that my battery is a single cell with a nominal voltage of 3.7V. Therefore, the Design Voltage should be 3.7V (1 * 3.7V). When I change the Cell Gain to 4.2V, the battery voltage suddenly drops. Why does this happen?

    3. If I change the Cell Gain manually, will it work?

    4. After generating a new GPCCHEM report, do I need to perform the learning cycle again?

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    1. A 3s configuration is short for 3 cells in series. If your pack has 3 cells in series, your design voltage would be the nominal voltage of an individual cell (as seen in the datasheet) * # of cells in series.

    2. This might imply that the gauge isn't calibrated yet. You can do a current and a voltage calibration to make sure your cell gain, bat gain and pack gain updates accordingly.

    3. We do not recommend manually changing the cell gain. Calibrating the gauge should automatically fix this.

    4. Yes, you would need to perform a learning cycle again.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    1. If I am using constant current, is it necessary to set load mode to 0 in Chem ID process?

    2. If I am using the golden image in the EVK with a power supply to provide a constant current for charging the battery and an electronic load to supply a constant current during the discharging process, it works fine. However, on a custom board, the battery may not receive a constant current while charging and discharging. How will the golden image function in this scenario?

    3. What should be the values of Load Select and Load Mode when implementing the learning cycle with an EVK using a power supply and an electric load for constant current?

    4. Additionally,After the learning cycle was implemented, the status was updated to 02. However, the full charge capacity fluctuates with each cycle. It varies between 330 to 390 mAH, while the Qmax is 400 mAH.

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    1. Is this for the GPCCHEM tool? You wouldn't need Load mode for this process.

    2. This is just for learning cycle purposes. Once you program the golden image, the gauge should be configured for the characteristics of your specific battery.

    3. We suggest leaving it to the default value for constant current.

    4. This is expected behavior. You can see how the FCC changes throughout the course of the cycle using the log file. Small variations are expected.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    1. As you mentioned, the gauge should be configured according to the characteristics of the specific battery. What specific characteristics should be configured? I am using the same battery for the custom board as I used to generate the golden file. If I set the load mode to 0 while performing the learning cycle, do I need to change the load mode to 1 when using it with the custom board?

    2. Isn't a 60mAh variation in FCC considered significant?

    3. During the discharging process, I set the load to -100mA and calibrated it in bqStudio to -100mA. The current is consistent, ranging from -97 to -100mA. However, when setting the load to -40mA and calibrating it, the current varies between -38 to -41 or -44mA. Is this acceptable for the Chem ID process?

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    Achieving The Successful Learning Cycle (ti.com)

    https://www.ti.com/lit/ug/sluubu0a/sluubu0a.pdf

    1. Refer to the documents above to set specific dataflash parameters. You do not need to change the load mode at all since you are applying a constant current load. This also does not affect the learning cycle process.

    2. Is this variation between different cycles or just throughout the course of one cycle? FCC shouldn't be looked at until the end of the learning cycle.

    3. You only have to calibrate this once, set the load to -100mA and calibrate the gauge. Do not calibrate it again.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    1. After performing the learning cycle in the EVK and generating the golden image using the battery LP353035 400mAh 3.7V, I program this golden image into a custom board with the same battery. Do I need to change the configuration? then what configuration? Additionally, the battery on the custom board may not receive a constant current during charging and discharging. How will the golden image function in this scenario?

    2. The variation we observed comes from testing the previously generated golden image. Due to potential parameter mismatches or chem-ID mismatches, as you suggested, I am repeating the process.

    3. Yes, you are correct, I have not calibrated it again. However, when I set the load to -40mA, the current varies between -38mA and -44mA. Is this acceptable for the chem-ID process?

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Mastermind 37761 points

    Hello,

    Today's a national holiday. We will get back to you tomorrow.

    Regards,

    TI Apps Team

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    1. You do not have to change the configuration. This is just for learning cycle purposes.

    2. I understand you are repeating this process, but does this difference come from the same cycle or from comparing between multiple cycles? My point about the FCC still stands, this should not be looked at until the end of the cycle.

    3. You can try setting the load to -400mA and calibrating the gauge. This is a larger than normal range after calibration.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    1. Yes, you are correct; it is for the learning cycle purpose. After generating the golden file, I flash the golden image onto the custom board, do I need to change the load mode to 1 since the battery on the custom board will not receive a constant current during charging and discharging?

    2. I have observed this difference on the custom board during a single cycle after flashing the golden file.

    3. As you mentioned, I need to set the load to -40mA, not -400mA. While calibrating it in the fuel gauge, the minimum current to calibrate is -100mA, and the current varies between -41mA and -44mA. How should I calibrate it in this case?

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    1. Since you are using a constant current load for the learning cycle, you should leave the load mode to the default value. Do not change this value.

    2. This is normal, do not look at the FCC until the end of the cycle.

    3. Calibrate the gauge with a -400mA load.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    I have completed the learning cycle up to step 3 (discharging process), and the update status has progressed to 05. However, it should update to 06 after the discharging process, but it has not. Can you help identify the possible reason for this issue?

    The Chem-ID I am using, according to the GPC report, is 2552, and the max DOD % is 1.82. Below are the log files & GPC report.log12-07.zip

    4237.GPCPackaged-report (1).zip

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    We noticed the R_DIS bit is being set during discharge. This implies that your ChemID isn't accurate. You should also try to discharge at a lower rate, try C/10 discharge. Your Ra tables haven't updated either. 

    Achieving The Successful Learning Cycle (ti.com)

    Follow the steps outlined in this document. Could you also send us the entire log file instead of just the discharge cycle and a datasheet for the battery?

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    I have been using the Chem-ID generated by the GPC report, which best matches. If the update status does not change to 06, do I need to restart the process from step 1 or step 3?

    Below, I have provided the complete logs of the learning cycle and the battery datasheet.

    Step 1 is to discharge at C/2 and then relax.

    dischg_log06-07.zip

    Step 2 is to charge at C/2 and then relax.

    charge_Logs09-07.zip

    After that, discharge at C/6 and then repeat the charge-relax-discharge-relax cycle, recording the logs in a loop.LOG10-07.zip2514.log12-07.zip

    Datasheet of Battery.

     LP353035 400mAh.pdf 

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    Thank you for providing the log files. We are looking into this and will get back to you soon.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    I have attempted to discharge using a C/10 rate, but the status is still not updating to 06. Can you suggest which Chem-ID I should use? I am currently using the updated Chem-ID 2552, and the maximum DOD is 1.82. Attached below is the Chem-ID report.

    3175.GPCPackaged-report (1).zip

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    The GPC report looks alright. Could you send me the log files for your C/10 discharge cycle? We need to see if Rdis is getting set again during the discharge cycle.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi,

    Attached below is the log file for the C/10 rate discharge. Despite this, the status has not updated, and the Ra-table and Qmax have not been updated either. Also I have noticed that RDIS bit was set during discharging.

    discharge_logs17-07.txt

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    After looking at the log, my suggestion would be to reduce the discharge rate a bit. You can try a C/8 discharge instead.

    Regards,

    Siddharth

  • 0 in reply to Siddharth Venkatesan
    Prodigy 10 points

    Hi Siddharth,

    Can you suggest which Chem-ID I should use? I have used the updated Chem-ID 2552, with a maximum DOD of 1.82, but it gets stuck at the discharging step and the status is not updating to 06. The Chem-ID report is attached below.

    0743.GPCPackaged-report (1).zip

    Thanks,

    Aachal

  • 0 in reply to Aachal Patel
    TI__Intellectual 2020 points

    Hello Aachal,

    THe GPC report usually has the best matched Chem-ID, so I would suggest keeping it the same as long as the procedure was followed.

    https://www.ti.com/lit/an/slva725a/slva725a.pdf 

    If C/8 discharge didn't work either, let's try doing this process again, starting from the ChemID selection.

    Send me the zip file you used for GPCChem tool, this should contain the configuration and the data file. We can proceed with the learning cycle process once that's done.

    Regards,

    Siddharth