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Original question:

BQ34Z100-G1: Problem with LOAD MODE and Learning Cycle

BQ34Z100-G1: BQ34Z100-G1

Emre B
Prodigy 40 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQSTUDIO, , BQ34Z100, BQ34Z110

Hello, I have couple questions about learning cycle.

1. From data memory part, I select the 'Load Mode' as 0, which is stands for 'Constant Current', and 'Load Select' as 'Average Current' . But it does not affect in the Control Status, ControlStatus<LDMD> is in set situation still. Does it cause any problem for the learning cycle, since I'm using the constant current? 

2. My battery type is Lead Acid 12V 1.3Ah. Before starting the learning cycle with sending IT_ENABLE command, is it necessary to wait at least 5 hours?

3. If the learning process is failed after IT_ENABLE command is sent, how can I change the update status as 0 for the purpose of starting the cycle again. Because  bqStudio does not allow me to write anything into data memory. I handle with this situation with programming with the .srec file where I found it in forum. (this file is not fully compatible with my battery) After I program, I'm able to write into data memory with the purpose of entering my battery specifications. Does programming with .srec file, which is not fully compatible with my battery, affect something on next learning cycle that I try. 

4. Added question: Sometimes, after IT_ENABLE cmd is sent, VOK bit does not goes HIGH even though the Voltage goes under the Cell Terminate Voltage which I configured in the IT Config in Data Memory during  the discharge. But QEN is HIGH after IT_ENABLE. 

Thanks a lot. That's all for now :)

  • 0
    TI__Expert 8315 points

    Hi Emre,

    When you say that the .srec is not compatible with your battery I am not quite sure what you mean. Could you provide me with some more info on exactly what you mean by this? Have you run a ChemID match?

    Thanks,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    Prodigy 40 points

    My battery is 1.3Ah. The .srec file that I found was 7Ah around. Also while ChemID of that file was 0x0808, mine is 0x0802.  Since I can not write anything to data memory after IT_ENABLE, I'm programming with this file. After that I'm getting able to write into data memory. The point is that I do not need this file to see something. I want to complete learning cycle. 

  • 0 in reply to Emre B
    TI__Guru** 105760 points

    Hello Emre,

    You should not upload .srec files found on the forum, they are most likely intended for a specific use case. You should download the default srec from the product page and use the as the baseline to upload the chem ID and make changes to data flash.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 40 points

    Thanks a lot for your answer. What about my 2nd and 4th questions? What should I care to start IT_ENABLE? Is OCVTAKEN = 1 or FIRSTDOD = 1 enough to start IT_ENABLE after discharging?

  • 0 in reply to Emre B
    TI__Expert 8315 points

    Emre,

    IT Enable should be sent before discharging when the battery is near full charge. I would suspect this is probably why VOK does not get set as well. I have attached a helpful document to this thread but I would take a close look at the learning cycle section for further details.

    Thanks, 

    Jackson

    5287.Practical_use_of_Single-Cell_Gas_Gauges.pdf

  • 0 in reply to Jackson DiGiovanna
    Prodigy 40 points

    Thank you Jackson! But I'm a little bit confused. Because, technical reference manual directs me more differently against to you said and shared document. 

    According to Figure 11.1 and 11.2 in the bq34z100-G1 Technical Reference Manual (Rev. A) page 58-59:

    -Firstly, battery should be discharged until it is empty. (precondition: RUP_DIS = 0, VOK =0)

    -After 5 hours relaxed, IT_ENABLE cmd should be sent. (see VOK=1 and UPDATE STAT = 0x04 then starts charging)

    But according to in the document that you shared, after battery is fully charged, IT_ENABLE cmd should be sent. And then discharge is needed.

    Like I said, I'm confused :) Which instructions are correct?

    Additionally, my battery's number of cell is 6. The cell size pass as single cell in the document you shared.

  • 0
    Prodigy 40 points

    I could not run the learning cycle as healthy. I've failed every time. I'm adding the log of my last try.

    In my last try meaningless things happened after IT_ENABLE cmd. VOK went high, but after a while dropped to low and RUP_DIS went high. 

    Since VOK is not set after IT_ENABLE most of time before, I've failed. But in my lastly I did confuguration as in def.gg. 

     duringFirstCharge.logdef.gg.csv

  • 0 in reply to Emre B
    TI__Expert 8315 points

    Hi Emre,

    I am looking at the second log right now as well as looking into why those documents have conflicting info. I'll get back to you with what I find.

    Thanks,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    TI__Expert 8315 points

    Hi Emre,

    The 34z100 Learning Cycle works a bit differently than other gauges so you can perform it either way. I would still recommend the flow I sent you in the pdf I sent over. Just be sure to send a RESET command after IT ENABLE. I believe the reason that the learning cycle is failing is that you are non achieving 90% DOD delta between your first two DOD readings. I would recommend charging the device to a greater voltage level before starting the initial discharge. QMax will not update and your learning cycle will continue to fail if this 90% difference between the first two DOD readings is not met.

    That being said, since you are using a PbA battery chemistry, I would look into using the BQ34z110 gauge instead of the BQ34z100 if you are not too far into your design process. The 34z110 is a pin to pin replacement that uses the CEDV gauging algorithm rather than impedance track. The CEDV algorithm is much better suited for Lead-Acid applications.

    Feel free to let me know if you have any further questions,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    Prodigy 40 points

    Thank you for your answer. I noticed some miss in my configuration. I'm planning to start from beginning with logging all things. But I have a couple questions more. If you anwer them, I'll be very pleasured.

    1. I did not look my battery chemistry ID, because there was only one 1.3Ah Lead Acid battery option in the Chemistry list. Is it possible that my battery has different chemistry? For example could my battery chemistry be 0x0808, which is belongs to 7Ah Lead Acid battery?

    2. After RESET cmd is sent, which is sent after IT_ENABLE, is it normal that RUP_DIS bit go high? Should I need to wait that RUP_DIS go low to start charging? 

    3. Is it necessary that discharging at C/5 rate? I'm discharging around C/3 rate to speed up the process. Is it necessary that charge current at C/2. I'm charging with C/3 rate to prevent any damage to occur on battery. 

    4. On my last try which I did with my final configuration, after charging VOK went low, but learning status was still 0x04. So, I decided to start discharging and charging process one more time. Would I should wait more time for the learning status to be 0x05 even if VOK goes low after charging. Or is the cycle failed? 

    Thanks a lot again!

  • 0 in reply to Emre B
    Prodigy 40 points

    After 4th issue on above, learn cycle became 0x05, and then 0x06. As a result, learning cycle had completed with one more charge and discharge process as different from the learn cycle guide.

  • 0 in reply to Emre B
    TI__Expert 8315 points

    Emre,

    Sorry for the delayed response.

    1. You can use the GPC Chem tool at https://www.ti.com/tool/GPCCHEM to check for the closest ChemID match to your cell.

    2. Yes this is normal. All Ra table updates are disable during the first cycle after a RESET command is sent. That bit should go low after your first cycle.

    3. C/3 is a bit high for discharging. You will introduce error when discharging at this rate. C/4 should be ok if you really want to speed up the process though. C/3 should be ok for charging though.

    4. VOK will go low whenever an OCV measurement occurs and will be high whenever your voltage is in the cell chemistry's "flat region" (where OCV measurements will not be valid for DOD updates). Once that measurement is taken you can begin your next cycle. Also just to clarify, this device can have the learning cycle performed starting from empty and thus the update status updates will happen differently than mentioned in the guide. Again simply to avoid confusion, I would not do this and start from full and discharge as mentioned in the guide. Following the guide I sent should yield successful results.

    Thanks,

    Jackson