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BQ27520EVM: 关于BQStudio 配合 BQ27520EVM 进行电池曲线学习的几个问题 Several questions about BQStudio and BQ27520EVM for battery curve learning

user6300248
Prodigy 90 points
Part Number: BQ27520EVM
Other Parts Discussed in Thread: BQSTUDIO, , BQ27520-G4

TI 技术支持您好，我已经准备好BQStudio 以及 EVM的环境，正在进行下一步的学习，有几个问题想咨询一下您：

Hi TI technical support, I have prepared the BQStudio and EVM environment, and are learning the next step. I have a few questions to ask you:

问题一：BQ27520EVM 开发版的PACK+ 、PACK- （连接充电器的 + 、 - ）允许的输入电压范围是 2.7～4.3 ，但是我们的电池充电电压必须在4.4V 才能充满。 我能否调整CHARGE的电压4.4V 接入EVM？

Question 1: The allowable input voltage range of PACK + and PACK- (+,-connected to the charger) of the BQ27520EVM development version is 2.7 ~ 4.3, but our battery charging voltage must be 4.4V to be fully charged. Can I adjust the voltage of CHARGE to 4.4V to access EVM?

问题2：关于学习周期目前我有两份文档，一份是BQStudio的SLUA903–July 2018   Achieving The Successful Learning Cycle 。  另外在BQ27520EVM开发版的 Users Guide 中也有关于学习周期的内容。 然而，经过我的研究，我发现两份文档的描述有不同点 ，我应该参照哪一份？

Question 2: Now I have two documents about the learning cycle. One is SLUA903–July 2018 Achieving The Successful Learning Cycle by BQStudio. In addition, there is a content about the learning cycle in the Users Guide of the BQ27520EVM development board. However, after my research, I found that the descriptions of the two documents have little different. Which one should I refer to?

问题3: 我倾向于按照文档SLUA903–July 2018   Achieving The Successful Learning Cycle 中的步骤进行学习周期。 在第一个环节我就碰到了问题，在5页的最底下，文档中的描述如下：

Question 3: I tend to follow the steps in the document SLUA903–July 2018 Achieving The Successful Learning Cycle. I encountered a problem in the first link. At the bottom of the five pages, the description in the document is as follows:

* Send IT (Gauge) enable command (0x21), or use the GAUGE_EN command to set the GAUGE_EN in
manufacturing status register and QEN flags in IT Status register. Then send the reset command
(0x41), or select RESET, to set the RDIS flag and disable resistance updates during this initial
discharge cycle. In this case, since IT has already been enabled, there is no need to disable it again
during the entire learning cycle. Once IT has been enabled, verify the Update Status has changed to
04 in the Gas Gauging, State section of Data Memory.
* Discharge the battery until the voltage reaches the Term Voltage.
疑问点1:在开始第一个环节之前电池是否必须满容量
疑问点2:当我点击BQStudio中的IT_ENABLE按钮后。Update Status 标识位并未被设置
疑问点3:CHEM ID 未指定是否有较大影响？是否导致了疑问点2？

Q1: Does the battery have to be full before starting the first link
Q2: When I click the IT_ENABLE button in BQStudio. Update Status flag is not set
Q3: Is there a big impact if the CHEM ID is not specified? Did it cause  Q2?

  • 0
    TI__Guru 52115 points

    See my comments below.

    Question 1: The allowable input voltage range of PACK + and PACK- (+,-connected to the charger) of the BQ27520EVM development version is 2.7 ~ 4.3, but our battery charging voltage must be 4.4V to be fully charged. Can I adjust the voltage of CHARGE to 4.4V to access EVM?

    Andy:  It should be okay to use the 4.4V charging voltage. However, I would suggest you check the battery specification and make sure the charging voltage is proper.

    Question 2: Now I have two documents about the learning cycle. One is SLUA903–July 2018 Achieving The Successful Learning Cycle by BQStudio. In addition, there is a content about the learning cycle in the Users Guide of the BQ27520EVM development board. However, after my research, I found that the descriptions of the two documents have little different. Which one should I refer to?

    Andy: The first one is a general guideline for gauge devices. It has a lot of details but some details might not be applied to all the devices. The second one is focusing on the learning cycle using bq27520.  I would suggest you read through both.

    Question 3: I tend to follow the steps in the document SLUA903–July 2018 Achieving The Successful Learning Cycle. I encountered a problem in the first link. At the bottom of the five pages, the description in the document is as follows:

    Q1: Does the battery have to be full before starting the first link

    Andy:  No.

    Q2: When I click the IT_ENABLE button in BQStudio. Update Status flag is not set

    Andy: Check the QEN bit in the Control Status. You should see it becomes 1 when you send the IT_ENABEL command.

    Q3: Is there a big impact if the CHEM ID is not specified? Did it cause  Q2?

    Andy:  A proper chemistry id must be programmed prior to the learning cycle.  Otherwise, the learning cycle will most likely fail.

  • 0 in reply to Andy Liu (BMS)
    Prodigy 90 points

    Thank you for your reply ！！

    The following is the learning cycle enumerated by  the users guide of BQ27520EVM. But I still  have a few questions about the details.

    ### (5A-5B) 1. Start with a discharged,                  ---> Q1: Just connect the battery and discharge without any other steps?
    relaxed battery                                                        ---> Q2:  I should verify control status : RUP_DIS、VOK = 0  after relaxed step ?
    2. Run IT_ENABLE command from                        ---> Q3: After I click IT ENABLE,  I should verify Bit  QEN  = 1 . wether Update status0  == 0x04 is needed? 
    the commands window
    3. Charge cell to full capacity                                 ---> Q4: In this step ,should i verify FLAG  FC =1 ?           
                                                                                   ---> Q5: Is it necessary to add a relaxation step here? 
    4. Discharge at C/5                                                
                                                                                   ---> Q6: Is it necessary to add a relaxation step here?                               
    5. Check to see that
    UPDATE_STATUS data flash                                ---> Q7:Is  Update status0 in [ Data Memerory ->Gas Guaging -> State] only change once is this step?
    value is 2

    ###(5C1) Write Ra Table, Qmax, Cycle Count and Update Status to gauge    ---> Q8:Is this operation done automatically by the BQStudio ? what should i do ?

    ###(5C2) Reset Gauge                                         ---> Q9: Click RESET button in BQStudio，Are there any other flags I need to verify？How can I know if the                                                                                                  learning cycle is complete successfully ？

    ###(5C3) Read flash, save golden .SREC,.BQFS, and .DFFS files   --->  Q10:Is the only thing I need to do at this step is to click the “ Create Image Files”                                                                                                                                button  in Golden Image ? 

    I'm so sorry I have so many questions about this, but in order to complete the whole battery calibration, I have to figure out every aspect of it. Is there anything missing in the above understanding of the entire process? If yes, Could you please also point out ? Thank you for your patience and look forward to your reply as soon as possible. Thank you again!

  • 0 in reply to user6300248
    TI__Guru 52115 points

    Take a look a the Section 2.6 of the app note below.

    http://www.ti.com/lit/an/slua902/slua902.pdf

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 90 points
    Hi, Andy Liu ! Thanks for the documentation ,  here is the section 2.6 
    1. Enable impedance track (0x21), issue a reset command (0x41).
    2. Discharge the cell to empty and let it relax for 5 hours.
    3. Charge the cells to full ensuring that the current goes below taper current and fc bit gets set, then let it
    relax for two hours. Qmax updates at this point and update status goes to 01. At least 90% of the cells
    design capacity has to go into the battery for qmax to learn. The learning cycle must be done at room
    temperature.
    4. Discharge the cells to empty using the typical discharge rate of your application. It must be between
    c/5 to c/10 rate otherwise learning will fail. Resistance tables will get updated during this discharge
    cycle.
    5. Let the cells relax for 5 hours. Update status would have changed to 02 before the end of relaxation
    indicating learning cycle was successful. If Update status is not 02 at the end of learning, go back to
    step 3 and repeat the process one more time.
    At third step, after battery has fully charged, the FC flag also show high. When flag VOK、 RUP_DIS is 0,
    the update status is still 0 . There is no automatic change to 1 as described above 。
    Q1：What may cause the update status to not change to 1 ？ What will happen if this does not become 1 .
    Q2:  I  write this value as 1 manually and then go to the next steps ,does it ok ?
     
    Looking forward to your reply， thanks ！
  • 0 in reply to user6300248
    TI__Guru 52115 points

    At least 90% of the design capacity has to go into the battery for QMax to learn. 

    Make sure the Term Voltage is set to the minimum voltage of the battery as specified in the manufacturer’s datasheet. Also, discharge the battery to that minimum voltage as well.

    You CANNOT change update status by yourself.

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 90 points

    Hi,andy:

    I have referred to the SLUA902-Start Guide for the BQ27520-G4 document for two cycles of learning, but both cycles of learning have failed. My steps are as follows:

    1. Set the chemical ID acquisition to 1785 with a deviation of 6%. programming Chem id
    2. Set the data parameter as follows:
    ### Design Capacity: 5700 mah
    ### Taper Current: 70 ma
    ### Dsg Current 45 ma
    ### Chg Current: 40 ma
    ### Quit Current: 10 ma
    ### Terninate Voltage: 2750 mv
    ### Final voltage: 2750 mv

    3. start log
    5. start learn cycle.

    The learning cycle as seen in Figure 8 is as follows:
    1. Enable impedance track (0x21), issue a reset command (0x41).
    2. Discharge the cell to empty and let it relax for 5 hours.
    3. Charge the cells to full ensuring that the current goes below taper current and fc bit gets set, then let it
    relax for two hours. Qmax updates at this point and update status goes to 01. At least 90% of the cells
    design capacity has to go into the battery for qmax to learn. The learning cycle must be done at room
    temperature.
    4. Discharge the cells to empty using the typical discharge rate of your application. It must be between
    c / 5 to c / 10 rate otherwise learning will fail. Resistance tables will get updated during this discharge
    cycle.
    5. Let the cells relax for 5 hours. Update status would have changed to 02 before the end of relaxation
    indicating learning cycle was successful. If Update status is not 02 at the end of learning, go back to
    step 3 and repeat the process one more time.

    Here are the problems I encountered:
    In the third step:
    Q1: The charging current has dropped to 20ma, the FC flag is still not set
    Q2: update status is not automatically set to 1
    Q3: Which value does Qmax update depend on? Is it data memory-> gas guage-> state-> Qmax cell?

    Q4: ra table is not updated in the fourth step

    I can't tell which part I did wrong, please provide support. It is best to add my WeChat or qq to communicate directly, I can shoot you a video. This problem has really troubled for a long time, could u please help me to solve these problem ,thanks

    qq: 376873271
    WeChat: 13738618437
    Email: 376873271@qq.com

    Thank you again !

  • 0 in reply to user6300248
    TI__Guru 52115 points

    To find out what happened to the FC bit in your learning cycle, I need to see a bqStudio log file. Could you provide it?