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BQ27Z561-R2: The procedure for training a battery utilizing the BQ27Z561 fuel gauge IC and BQ Studio.

Ruchika Bagal
Prodigy 20 points
Part Number: BQ27Z561-R2
Other Parts Discussed in Thread: BQ27Z561

Hi,

I am currently in the process of configuring the necessary parameters to initiate the learning cycle. However, I am encountering challenges in obtaining the correct values for the below mentioned parameters.

  • Charge current threshold
  • Discharge current threshold
  • Charge term taper current
  • Quit current

A critical condition for a successful learning cycle is to ensure that the charge current threshold is less than the termination taper current and quit current. Despite my efforts, I am struggling to determine the appropriate value for the charge term taper current.

The battery which I am using for my training process is LP353035 with 400mAh having typical voltage of 3.7V.

I have experimented with various resistor values which is connected to the JP9 connector in the EVM, each yielding different results:

  1. Resistor with 40.2K: In this scenario, the current dropped to zero from 400mA.
  2. Resistor with 150K: I encountered difficulty in obtaining complete logs of the average current.
  3. Resistor with 220K: Difficulty in obtaining complete logs of the average current.
  4. Resistor with 300K: In this case, the current dropped to zero from 131mA within one second, despite the required elapsed time being 80 seconds.

Given the above observations, what changes I need to make to obtain the correct parameters for the learning cycle.
I am attaching the log files of all the four experiments I did, please go through it.
charging_40.2K.logcharging_150K.logcharging_220K.logcharging_300k.log

Thanks,
Ruchika

  • 0
    TI__Mastermind 18591 points

    Hello Ruchika, 

    Please refer to section 2 of the Achieving The Successful Learning Cycle document. This section goes over how to determine what values you should have configured to perform the successful learning cycle. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,
    The battery I am using is LP353035 of 3.7V and of 400mAh capacity.

    As per the GPC package report, the chemical ID I am programming into the gauge(BQ27Z561) is 2003 with maximum DOD of 2.37%. Even though my battery type is LiPo but the best matching chemical ID which I am programming according to the report is NiCoMn which I can use right?
    The parameters which I have configured according to the document which you have referred above are listed below but those are not satisfying the condition i.e., charge current threshold < term taper current > Quit current.
    Could you please verify these parameters and suggest me if any changes I need to make?

    1. Charge term taper current - 25mA
    2. Discharge current threshold - 40mA
    3. Charge current threshold - 3000mA
    4. Quit current - 20mA

    I am attaching the report and , please go through this.
    0451.GPCPackaged-report.zip

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    Yes you should be using the 2003 ChemID since this DoD% error is less than 3%. Additionally, you should configure the gauge so that the Taper current > Charge current threshold > Quit current. The Chg Current threshold should be set lower than the Charge Term Taper current. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hello,


    I am stuck at the third step of the learning cycle procedure where the bits VCT, MCHG and FC are not getting set in the battery status register. 
    I am using the below given parameters into the gauge data memory for the implementation, could you please verify if the parameters I am using for the procedure are correct or not?

    1. Charge term taper current - 40mA
    2. Discharge current threshold - 35mA
    3. Charge current threshold - 25mA
    4. Quit current - 20mA

    Also, I have tried charging the battery with various resistor values such as 40.2K, 150K, 220K and currently it's 300K that is placed and the observation that I have made with 300K is that the current is directly dropping to zero from 131mA in1second only. The log file for charging of third step is attached here with,
    0027.charging_40.2K.log4212.charging_150K.log7026.charging_220K.log0083.charging_300k.log

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    For the Charge Term Taper current, this is dependent on the charger taper current. It is recommended to set the Charge Term Taper Current to be 10% higher than the charger taper current. 

    For the Discharge Current Threshold, it is recommended to set this to a value below C/10. 

    For the Charge Current Threshold, it is recommended to set this value lower than the Charge Term Taper Current. 

    For the Quit Current, it is recommended to set this value to be less than C/20, and this value must be less than the Discharge Current Threshold and the Charge Current Threshold. 

    So please ensure that these values are configured accordingly. 

    Additionally, what is the reasoning for connecting these various resistor values to the J9 jumper on the EVM? 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    I again failed at the third step of the battery charging where the FC, VCT and the MCHG bit did not set.

    Below I have mentioned the parameters that I am using, please check if I need to change any value:-

    Design capacity mAh 400mAh
    Design capacity cWH 148cWH
    charge term taper current  40mA
    Discharge current threshold 35mA
    Charge current threshold 32mA
    Quit current 30mA
    Charge voltage offset 250mA
    Charge term voltage charging 4200mV
    FC set voltage threshold 4200mV
    FC clear voltage threshold 4100mV
    FD set voltage threshold 3000mV
    FD clear voltage threshold 3100mV

    I have attached two different log files of the procedure that I performed, please go through it and let me know where the error is occurring.

    Learning_procedure.logLearning_logs.log

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    Can you send your latest gg file? Additionally, what is the reasoning for connecting these various resistor values to the J9 jumper on the EVM?

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,
    sure! I am sharing the zip folder of all the gg files that were created and also the log file. Please go through it.

    As our battery capacity is 400mAh, we changed the resistor to 300K to reduce the charging current.

    2287.gg.zip.zip4353.Learning_logs.log

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    You should not be using resistors to control the charging current, and instead should have your charger control the current being used.

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    We've been troubleshooting an issue with our charger EVM. Despite adjusting resistor values, we're encountering a problem in the third step where the FC and VCT bits aren't setting properly and I don't think that the issue lies in varying the resistor values. 

    Our battery specifications are 3.7V and 400mAh so we have adjusted resistor value to set charging current accordingly.

    Could you take a look at the attached log files and help us diagnose what might be causing this?

    0172.gg.zip.zip2248.Learning_logs.log

    Regards,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    Please refer to the following screenshot taken from the TRM. The FC bit is just a flag that gets set based on the values you have programmed for either FC Set % RSOC Threshold or FC Set Voltage Threshold. The gauge can only use either FC Set % RSOC Threshold OR FC Set Voltage Threshold to trigger the FC flag bit, but not both. To use FC Set Voltage Threshold to trigger the FC bit, you must set FC Set % RSOC Threshold to equal -1%, otherwise the gauge will use the FC Set % RSOC Threshold value to set the FC flag bit. 

    Additionally, for the VCT bit to set, all of the conditions highlighted in the following image must be met. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    I have changed the parameter values of the FC bits, but still the value of update status is not updating to 0x05 it's still 0x04.

    The previous value of the FC set voltage threshold and FC clear voltage threshold was 4.2V and 4.1V respectively. Then, I changed it to 3.7V and 3V respectively.

    I also waited for the complete relax duration but still it did not change the bit. Could you please help me in finding what can be the issue in the proper implementation of the learning cycle.

    Below I have mentioned the parameters that I have used.

    Design capacity mAh 400mAh
    Design capacity cWH 148cWH
    charge term taper current  40mA
    Discharge current threshold 35mA
    Charge current threshold 32mA
    Quit current 30mA
    Charge voltage offset 250mA
    Charge term voltage charging 4200mV
    FC set voltage threshold 3700mV
    FC clear voltage threshold 3000mV
    FD set voltage threshold 3000mV
    FD clear voltage threshold 3100mV

    Also, I am attaching the zip folder which contains the log files and the gg files of the test performed, please go through it.

    Learning_cycle.zip.zip

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    I recommend referring to this FAQ titled "Why is the Update Status not updating from 4 to 5?" as I believe this could help you. Please take a look at this FAQ and let me know if this helped here. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,
    I went through the document and the FAQ you recommended and did the changes according to that but still the cycle is stuck at the third step.

    The FC, VCT and the MCHG bits are not getting set after the charge.

    The updated values I am mentioning below, please go through it.

    FD set voltage threshold 3000
    FD clear voltage threshold 3100
    FD set % RSOC threshold 0
    FD clear % RSOC threshold 5
    FC set voltage threshold 4100
    FC clear voltage threshold 4000
    FC set % RSOC threshold 0
    FC clear % RSOC threshold 5

    The value of the TD and TC are same as FD and FC respectively. Also, the value of the taper current which I am using is 40mA and the current threshold parameters i have configured is according to this value of the taper current only.

    Can you suggest me any other way by which I am able to successfully implement this learning cycle? I am attaching the log files and the gg files of the procedure below.

     logs.zip.zip8130.gg.zip.zip

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 21300 points

    Hello,

    Jonny is out of office today. Please expect a delayed response.

    Regards,

    Anthony Baldino

  • 0 in reply to Anthony
    Prodigy 20 points

    Hi,

    Could you please let me know if there is another expert available who might be able to assist me with this issue?

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello, 

    To answer your question on why the FC bit is not getting set, you have the FCSETVCT bit enabled. When the FCSETVCT bit is enabled, the FC bit will only get set once the valid charge termination conditions are satisfied. This also means that the FC bit is NOT dependent on the FC Set Voltage Threshold or the FC set RSOC threshold. This is why when you change the FC Set Voltage Threshold to a lower value, you are not seeing the FC bit get set. The likely reason here you are not completing the learning cycle is because you are not satisfying the Valid Charge Termination conditions listed in the gauge TRM.

    Please ensure that you are satisfying all of these above conditions. Once you satisfy the valid charge termination conditions you should see the VCT bit get set, the MCHG bit get set, and the FC bit get set. 

    Regards, 

    Jonny.  

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    I made changes according to the valid charge termination condition and after applying all those necessary changes the FC, VCT and the MCHG bits are getting set but now I am facing problem in updating the update status from 04 to 05. 

    I also referred to the forum you suggested for the issue in changing the update status from 04 to 05 but it did not help.

    Can you provide me with any other suggestion that can help? I am attaching the log files below, please refer it.

    Learning_21-05-24.zip.zip

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    Prodigy 20 points

    Hi,

    I've made changes according to the valid charge termination condition. After implementing these changes, the FC, VCT, and MCHG bits are getting set correctly. However, I am now facing an issue with updating the update status from 04 to 05. Despite referring to the suggested forum for resolving this issue, I haven't found a solution.

    Additionally, I've noticed that once the battery is in a relaxed state after charging, the FC and MCHG bits are not clearing automatically as expected when the voltage level drops.

    Can you provide me with any other suggestion that can help? I am attaching the log files below, please refer it.

    3678.Learning_21-05-24.zip.zip

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    After looking at the log file that you had sent over, it looks like your voltage and current is quite unstable for the learning cycle (see image below). 

    Your voltage and current plot should look more like the following: 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,
    There is another setup with the same battery where I am implementing the learning cycle. However, I am encountering an issue with this battery: the REST bit is not setting after a complete relaxation period following the charging step. The configuration parameters for this battery are the same as for the previous one. Could you please check the attached log files and help identify the issue?
    5707.LOG.zip
    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    Looking at your log file you sent over, it looks like this is still similar to my last response (see graph below). 

    Please refer to my previous response on the correct voltage and current plot. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    I wanted to ask what can be the reason for this fluctuation in the voltage and current values. I am using TENMA power supply to supply constant current to the battery for the charging and TENMA electronic load for providing the constant current during the discharging process.  Despite observing stable readings on the device displays, the fluctuations persist.

    The battery i am implementing the learning cycle on is LiPo of 400mAh, 3.7V with chemical ID 2003 and maximum DOD of 2.37%. Should I keep the relaxation period of the battery 5 hours or it should be more than that? Because the update status has still not changed to 05 after multiple attempts.

    Additionally, I have one dialog charger circuitry connected to the fuel gauge EVM which is being used for the charging process.

    Can you suggest what is causing this instability in the voltage and current values?

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    The fluctuation in the voltage and current values is likely caused by the charger you are using. Additionally a potential reason you are not getting update status to change to 0x05 is that in the log file you have sent it looks like you are not completing the full process, please see the image below for what the learning cycle voltage and current should look like. 

    Additionally, another potential reason for update status not changing to 0x05 is that you are not achieving the 90% change in DOD required. This 90% change in DOD is based on the design capacity of the cell that you have configured into the gauge. In order to achieve this, it is important to complete the learning cycle with the charge voltage and terminate voltage specified by the cell datasheet, and not the values for your system. This should help ensure that you are achieving the 90% change in DOD. 

    Regards, 

    Jonny. 

  • 0 in reply to Robert
    Prodigy 20 points

    Hi,

    My update status has changed to 05, but this occurred after the second discharge cycle instead of following the relaxation period after charging, as expected. I have few questions regarding the same and also about the chemical ID we are using.

    1. Despite the update status being updated, the Ra table remains unchanged. According to the reference manual, this table should update during the discharge cycle. Why is this not happening?

    2. According to the GPC package report, the chemical ID programmed into the BQ27Z561 gauge is 2003, with a maximum DOD of 2.37%. Although my battery type is LiPo, the best matching chemical ID is for a NiCoMn battery. Could this mismatch between the battery type and the chemical ID be causing the issues I'm facing?

    3. In another setup on a different PC, I programmed a different chemical ID (1123) from the GPC report, which has a maximum DOD of 2.57%. In this setup, the FC, VCT, and MCHG bits are not setting after charging, even though I configured the same parameters as in the previous setup. Could the different chemical ID be the reason for this discrepancy? 

    I am attaching the GPC report below so that you can check the suggested chemical ID's I am using in two set up's.

    5086.GPCPackaged-report.zip

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello Ruchika, 

    The update status changing to 0x05 does not mean that the Ra table has been updated. This is explained in the Achieving the Successful learning cycle document I have previously provided. 

    You should use the chemID that is the best match for the cells that you are using. 

    Additionally, please see my previous responses on the potential reason you are not able to complete the learning cycle. 

    Regards, 

    Jonny.  

  • 0 in reply to Robert
    Prodigy 20 points

    Hi, 
    I have referred to the document and have done the procedure according to that, but I am not able to determine why my Ra table is not updating.

    Can you suggest what can be the possible reasons for this issue?

    Thanks,

    Ruchika

  • 0 in reply to Ruchika Bagal
    TI__Mastermind 18591 points

    Hello, 

    Are you comparing the Ra table from before the learning cycle to the Ra table from the gg file after the learning cycle to see if the Ra has been updated? What is the C rate that you are discharging at? 

    Regards, 

    Jonny