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BQ40Z80: + bqstudio

Vladimir Raikhman
Prodigy 20 points
Part Number: BQ40Z80

Hello

Number of cycles and SoH has been changed!

I have updated some protection parameters to 8 batteries with BQ40Z80 BMS.

After update (some of Protection parameters was changed and Write_All was performed), Cycle Number that was more then 100 changed to 30.

In  addition, state of health was changed after update on a couple of batteries from 93 to 99%.

The battery analyzer Version : 1.3.101 Build 1.

writing of which parameter could affect Cycle Number and SoH?

Thanks in advance,

Vladimir

  • 0
    TI__Guru** 105770 points

    Hello Vladimir,

    What values did you change and how did you upload the changes?

    Nothing the cycle count should not change unless it's been reprogrammed. If you modified a .gg file and then uploaded it that would change the cycle count also.

    Sincerely,

    Wyatt Keller

  • +1
    Prodigy 20 points

    Hello Wyatt

    I did write the hole gg file, that I had exported from one battery to other.

    Just realized that it is writable register!

    Thank you

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Additional question - 

    when writing the gg file, what parameter can influence the current battery SoH?

  • 0 in reply to Vladimir Raikhman
    TI__Guru** 105770 points

    Hello Vladimir,

    The Ra and Qmax changing can affect the SOH.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Hi again

    In general, if I export the gg file from one battery and write the whole file to another battery, it will destroy the Calibration parameters also.

    Am I right?

    Can I use such a battery?

    Can I restore  a original parameters in some way or all the measurement of such battery will be incorrect?

    Thanks in advance!

    Vladimir

  • 0 in reply to Vladimir Raikhman
    TI__Guru** 105770 points

    Hello Vladimir,

    By default the calibration data will not be uploaded to the gauge from a .gg file. You can select it using the advanced import option.

    It depends how different your calibration values are. If you calibrate each pack and you accidently wipe the calibration information, I would recommend re-calibrating the values.

    Some customers average the calibration values from many packs and use this in their golden image (srec).

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Thank you Wyatt!

    we are using 5S2P configuration of 18650 and also 21700 batteries .

    as a life-time test we are running cycles with target load and charge the packs with 3A charger.

    till now we performed 100 cycles and it is clear degradation of cycle time of ~15%.

    I mean - the same target runs with the same pack 15% less in time, comparing to cycle 1 and even 50.

    SoH had degraded not more then 4%.

    Which parameter, in your opinion, could influence cycle time?

    The CUV in our case always was 3V...

    Can I send the gg file for your review?

    Thanks in advance

  • 0 in reply to Vladimir Raikhman
    TI__Guru** 105770 points

    Hello Vladimir,

    Make sure you use the correct bqz with the gauge, it should autodetect. If you have to manually select the bqz you may be using the incorrect one, this can lead to data flash corruption.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Hi 

    the BQ is autodetected without problems.

    Could you try to advice about my questions about degradation, parameters and gg file?

    Just repeating in case you cannot see it before:

    "

    we are using 5S2P configuration of 18650 and also 21700 batteries .

    as a life-time test we are running cycles with target load and charge the packs with 3A charger.

    till now we performed 100 cycles and it is clear degradation of cycle time of ~15%.

    I mean - the same target runs with the same pack 15% less in time, comparing to cycle 1 and even 50.

    SoH had degraded not more then 4%.

    Which parameter, in your opinion, could influence cycle time?

    The CUV in our case always was 3V...

    Can I send the gg file for your review?

    "

    Thanks in advance,

    Vladimir Raikhman

  • 0 in reply to Vladimir Raikhman
    TI__Guru** 105770 points

    Hello Vladimir,

    I'm not sure I understand your questions. Is cycle time the time it takes to discharge the battery? CUV does not influence the cycle count.

    Is the 100 cycle count and 15% degradation what you programmed? But it's only 4% SOH degraded?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Hi Wyatt,

    - cycle time the time it takes to discharge the battery

    - CUV will stop cycle time. correct?

    - we have ran 100 cycles. and saw that after 100 cycle, the time was shortened.

      so I wonder what could be a reason if SoH looks ok.

    Thank you for your support!

  • 0 in reply to Vladimir Raikhman
    TI__Genius 10370 points

    Vladimir,

    Cycle count counts up when you discharge a percentage of design capacity in mAh. So if your battery is 1000. and the cycle count threshold is 90% going from 100%-10% (in mAh) will count cycle count +1. Alternatively if you cycle 100%-90% 10 times this will also count cycle count +1. As you cycle the battery your QMax will decrease and your resistance will increase (normal aging). This means you will charge and discharge shorter amounts of time since the battery will accept less capacity. 

    If you are doing non-stop cycling for 100's or cycles. the gauge is most likely not learning the battery impedance as it ages. this will cause inaccuracy in general. I suggest running a Charge, relax, discharge, and relax test to see what Qmax and Ra update to. Once you get a proper updates then SOH should be more accurate.

    Thanks,

    Eric Vos

  • 0 in reply to Vos
    Prodigy 20 points

    Thanks!

    how much relax time would you recommend between charge/discharge/charge?

    so you suggest to record also Ra and QMAX for further analysis. right?

    Have a good day,

    Vladimir

  • 0 in reply to Vladimir Raikhman
    Prodigy 20 points

    in addition: what will be the most reliable aging indication? SoH, QMAX, Ra?

    thanks again

  • 0 in reply to Vladimir Raikhman
    TI__Guru** 105770 points

    Hello Vladimir,

    The gauge uses Qmax and Ra tables for the SOG calculation. The max times for a OCV update after a charge is 2 hours, after a discharge is 5 hours. An OCV will be taken when a 4uV/s is met. You can check the REST bit in the gauge when an OCV occurs. You can use the Qmax bit to see if a Qmax was updated. And you can use VOK to determine if the cycle is good for a Qmax update.

    You can find more information about the Qmax update bits in SLUA903.

    Sincerely,

    Wyatt Keller