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BQ27500-V130: IT ENABLE not being set, Update Status 0 not updating during learn cycle

user3793349
Prodigy 190 points
Part Number: BQ27500-V130
Other Parts Discussed in Thread: BQEVSW, BQ27510, BQ27500, GPCCHEM

Hello, 

I am working with the 27500-V130 EVM and trying to create a golden image for a new cell we are using.  I have been trying to run the learn cycle over the last couple weeks and have two issues, which are probably linked.  

1).  Any attempt I make at initializing impedance tracking does not seem to work.  When I click the initialize button as part of the 4 step learn procedure, the control register never updates to 0021.  However, VOK and QEN get set.  Control always shows 000B or 000C or other values that i have no idea what they are [NOT 0021].  If I try to manually write 0021 to the flash, when I click enter it just reverts to whatever the value was.  

2).  Update Status 0 never changes after discharge, charge and discharge ultimately leading to failure of creating golden image. 

Some information regarding my set up:

- The cell I have is a 305mAH Li/NCA cell, and customer provided "closest chemistry is 210".  So I chose the 0210 chemistry.  That is all i know about cell. 

- I selected internal temp sensor and have an 8.2K resistor connected between BI/OUT and PACK -.  BAT_DET register is set (wasn't previously setting until I connected external resistor)

- All my configurations have been set up [4.1V charge, 305mAH capacity, constant power output etc...]

- Registers seem to be showing proper operation, which is confusing me more on why IT_ENABLE and UPDATE STATUS 0 are not working.  CHG and DSG set during charge and discharge, VOK and QEN get set before charging and after I click the "initialize IT" button and fuel gauge on bottom left goes from 0-100 when charging and from 100-0 when discharging [how accurate it is I dont know].  

Lastly, I am not following the 2hrs after charge and 5 hrs after discharge, these times are much longer.  I have followed same timing on all my attempts:

1).  Start with fully charged and relaxed battery.  Discharge down to 3V with C/5.  [rather than 5hrs, system sits overnight]

2).  Next morning click "Dsg/Wait Done" and "Initialize IT" and charge to full 4.2V with C/2 and click "Charge/Wait Done" after 2 hrs so FC bit doesn't clear.  Then system sits overnight.

3).  Next morning begin discharge to 3V with C/5.  At this point, I can see UPDATE STATUS is still 0.  As far as I have gotten.  

Any ideas on something/things that I am doing wrong?  

Mike

  • 0
    TI__Guru* 76230 points
    Hi,
    If IT is not enabled, there is no way learning would succeed. You need to check to see why it isn't being enabled. When you send the IT enable command, what happens? Do you get an error? A screen shot of your bqEVSW and a copy your data flash gg file would be needed for further analysis . How do you know the chem id provided you is the close match? Did your vendor send you the gpc report that our tool provides to know how close a match is your cell is?

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    TI__Guru* 76230 points
    Also, why are you using the bq27500? that is a legacy old device. I would recommend using the bq27520 or the bq27510.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 190 points

    Thank you for response. Just for upfront clarification, can you confirm I am "sending IT enable command" correctly? By this I mean just clicking the INITIALIZE button in the 4 step BQeasy window. Is there more to it than just clicking INITIALIZE? [When I mentioned I manually tried also, I went to the dataFLASH window, gas gauging tab and updated the IT ENABLE value to 0021 and clicked WRITE ALL. Is this incorrect also? When I click INITIALIZE, it just greys out and moves on to next step. No errors or any acknowledgment.

    Vendor sent nothing other than just a statement saying chemistry closest matches 210. If the problem lies here, I would have to get more information from them.

    Also, we are updating some hardware here for using custom cells.  Design uses legacy gauge. 

  • 0 in reply to user3793349
    TI__Guru* 76230 points
    You need to send IT enable by sending command 0x21 in the control access (maybe it is manufacture access field on this gauge). ie on the register window, you go to the field for control access and simply type 21 and hit enter. The method you are using is incorrect. Again i have to reiterate that this gauge you are using is older and a better fit would have been the bq27520 or bq27510 which have improvements from the bq27500.

    You can run the test your self to determine if it is a good fit using our online tool gpcchem. This will help identify your chem id, before you start your learning cycle but you need to ensure you know how to enable impedance track correctly before starting your learning cycle.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 190 points

    Im sorry to keep making you explain further, but can you explain where control access/manufacturer access field is located?  Is pic below what you are referring to?  I can click on that, enter 21 and it takes, however if i click refresh it reverts back to 0130 value in there.  Do I just enter in 21 and begin charging and not click anything?  Right now my set up is still connected to the discharged cell, Im not actually doing a learning cycle yet.  Also [second pic] what is the point of the INITIALIZE button then?  Do I click this before entering in 21 into the control field?  

  • 0 in reply to user3793349
    TI__Guru* 76230 points

    Hi

    I see you have QEN flag set meaning impedance track has been enabled. It was either enabled from typing in 21 and hitting enter in the control field you  circled in ref or the initialize button you also circled. Now that you IT enabled you can now start the cycle as long as you have the chem id programmed on the gauge. If  learning fails, there could be a series of reasons that could be the cause. I would encourage you to log the data and send over including the gg file should learning fail. With the Continuous log file we will be able to determine if the chem if you chose is a good fit and one can check the gg file to make sure you have things set propely.

    To understand the learning cycle properly, i would recommend reading through the attached pdf.

    8640.LearningCycleOverview_.pdf

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    Prodigy 190 points
    Yes, per my original post this has been the source of my confusion. QEN and VOK registers set like they should be [VOK is set/cleared with charge/discharge I believe] however, the update status never gets updated from 00.

    I did notice under the chemistry 0210 group, cells listed are of much larger capacity. My cell is only 305mAH. Are those 4 or so cells that are listed under the 0210 group some examples, or the only cells that fit that group?
  • 0 in reply to user3793349
    TI__Guru* 76230 points
    You can have chem ids for a large capacity battery work for a small capacity cell. Their characteristics would be similar. The difference would be in qmax and cell resistance which is what the gauge is supposed to learn. So at this point, you need to first make sure the chem id you are using is a good match for your cells. Run the gpcchem tool (instructions are on the page of the tool) and make sure you are using a good chem id for your learning cycle.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 190 points
    Ok, Ill run this again and log. Now I have a better understanding and realize my IT ENABLE is being set, and has been. Now just have to see what's causing UPDATE STATUS to stay at 00. Everything seems to be set up correctly and follows charge/discharge of cell so not sure what issue there is. 8640 learning cycle overview document is another verification for me to follow, thanks.
  • 0 in reply to user3793349
    TI__Guru* 76230 points
    ok goodluck. Hopefully you are successful this time around. Let me know if further questions arise.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    TI__Guru* 76230 points
    It is likely your chem id might be incorrect, and that is why I am saying do the gpcchem test first to make sure and not just rely on what you were told by your vendor. Either way, even if the test fails this time around, you will be able to use that log files to check with the gpcchem tool your best chem id match.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 200 points

    If my design parameters are 4.1V charge [that is what I entered in the setup as system full charge voltage], do I charge to that or still charge to full 4.2V during the learning cycle?

  • 0 in reply to Mike Rogus
    Prodigy 200 points

    So I have run the charge cycle. Upon beginning, VOK and RUP_DIS were clear. I initialized IT ENABLE and QEN was set. Upon starting charging, VOK was set. at the end of charge when meter showed 100%, FC bit was set.

    After relaxing, VOK cleared. RUP_DIS was clear also. I clicked Chg/wait Done. UPDATE STATUS 0 is still 00.  Side note, the control register shows SLEEP set.  

    Last question, in DataRAM tab, the Nominal avail capacity and full avail capacity are both 299mAH.  Remaining capacity and Full charge capacity topped out at 292mAH.  In the Data Flash tab, the Qmax Cell 0/1 fields show 305mAH.  Is update status never setting due to being below 305 on everything?  

  • 0 in reply to Mike Rogus
    TI__Guru* 76230 points

    You must charge to 4.2 to ensure the 90% of design capacity passed charge  is met for qmax update.

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    Prodigy 200 points

    Hi, so I submitted the data for gpc tool and it came back with 2130 as best chemical ID.  2130 does not exist in the chemical ID list in the BQeasy tool.  Following that theres a summary list with 11 additional IDs, but again only 2 or 3 are avail in the BQ chemical list.  

    What determines my chemical selection in the tool, or what if its not in the list?

    Thanks much,
    Mike

  • 0 in reply to Mike Rogus
    TI__Guru* 76230 points
    Hi Mike,
    If the tool returns a chem id that is not in the list , then you need to update the tool. The updater will be on ti.com. In actuality, you can use any chem id that is under 3% max dod error.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 200 points

    OK thank you.  I ran the chem updater and used chemical ID 2130 per the TI report.  Ill try running the learning cycle again and see if this allows UPDATE STATUS 0 to update.  This seemed to be my only issue so hopefully its resolved with the new chemistry selection.  

    Mike

  • 0 in reply to Mike Rogus
    TI__Guru* 76230 points

    ok. Let us know how else we can be of help.

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    Prodigy 200 points

    Hi, 

    So i have run the first part of the learn cycle with the updated chem ID selection based on the TI report.  Still not updating??

    -Started with completely discharged and relaxed cell.  VOK and RUP_DIS were clear.

    -Charged cell to full 4.2V and <taper current setting.  QEN and VOK set during charging.  FC set near end of charging.  VOK cleared in 30 minutes into relaxing.  (from what I read, VOK clearing means first Qmax update occured, and UPDATE STATUS should be 0x01]  On a side note, not sure why VOK cleared so fast, based on my DMM, voltage still looks to be changing at a rate greater than 1uV/s

    In the data flash tab, under fuel gauging UDATE STATUS 0 and UPDATE STATUS 1 are both 00.  Screen grabs below.  i HAVE NOT clicked "Charge/wait done" button under the bqEasy learn cycle screen yet...  Just observing VOK and UPDATE STATUS

  • 0 in reply to Mike Rogus
    TI__Guru* 76230 points
    Hi Mike,
    Continue running the cycle, let the test complete. If you still don't have any updates occur at the end, attach the log and gg and srec files.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 200 points
    Ok I can do that. Ill have to finish this one out and then go again, as I have not been logging thus far.

    Can you confirm what the srec and gg files are and how to extract those?

    Thanks!
  • 0 in reply to Mike Rogus
    TI__Guru* 76230 points

    the srec or senc  is an image of the firmware of your chip. You can extract an senc file  using bqevsw. the gg file is a text file containing all the non-private parameters of the gauge

    bq20z gg and senc upload.pdf

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    TI__Guru* 76230 points
    Hi Mike,
    The EVM user guide has instructions on how to extract the gg file using bqevsw

    www.ti.com/.../sluu287a.pdf

    to extract an srec, send command 000f as shown in figure 10 of the evm user guide. this will put the device in ROM mode. Then click the file menu, extract senc.
    Hope this helps. I just realised the earlier document i attacahed is for an smbus device so there are subtle differences as this is an i2c device

    thanks
    Onyx