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BQ28Z610-R1: Doubts about Chemistry ID Matching

Eduardo Barcellos
Intellectual 420 points
Part Number: BQ28Z610-R1
Other Parts Discussed in Thread: BQ25883, BQ28Z610, BQSTUDIO, EV2400, GPCCHEM

Hello,

I have this circuit designed with a BQ25883 as charger and BQ28Z610 as gauge:

I'd like to clear some doubts about Chemistry ID Matching:

As I understand, to do the Chemistry ID Matching I need to:

1. Charge the battery to full
2. Let it rest for 2 hours
3. Discharge it to its minimal voltage
4. Let it rest for 5 hours
5. Log current, voltage and temperature vs. time across the entire process

If so, will my circuit above + EV2400 and bqStudio satisfy all of these requirements except #3?

Thanks for your help

  • 0
    TI__Expert 8365 points

    Hi Eduardo,

    Just to confirm, you are referring to the online GPC ChemID matching tool correct?

    If so then your assumptions are correct. However, I think your circuit + EV2400 + BQStudio should be able to do all 5 steps so long as you attach a load to sys to discharge the battery for step 3.

    Thanks and best regards,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    Intellectual 420 points

    Hi Jackson,

    Thanks for your reply. Yes, it is the online GPC ChemID matching tool.

    With your answer clearnig the previous doubts, our next one is about the charge step of the charge-relax-discharge-relax process for the online GPC ChemID matching tool:

    Can we simply charge the batteries normally using the BQ25883 on the board for this? (plug the USB to the board and charge it to full while logging with EV2400+bqStudio). Or does it need any special attention, setting or hardware?

    And does the batteries needs to start from empty? Or can it start charging from any DoD?

    Thanks again for your time

    PS: It's 2 series batteries.

  • 0 in reply to Eduardo Barcellos
    TI__Expert 8365 points

    Hi Eduardo,

    There shouldn't be any issue charging using the BQ25883. If this is the charger being used in production, it is actually better to do it this way so the tool can learn the parameters of the cells according to how it will be charged in your real application. I would start the charging process from empty though.

    Thanks,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    Intellectual 420 points

    Hello Jackson,

    Thanks again for your reply. Now our next doubt is about the discharge part of the charge-relax-discharge-relax process for the online GPC ChemID matching tool:

    As we read from SLVA725A, we assume that the load we attach to BQ25883's SYS pins for discharging the batteries must drain a constant current of about C/10 amps from SYS during the entire discharge part, and simply attaching a normal load to SYS will not work. Is that assumption correct? (i.e.: For a 1000mAh battery, our load must drain 100mA during the entire time)

    Thanks,

    Ed

    PS: Once again, it's 2 series batteries on our board.

  • 0 in reply to Eduardo Barcellos
    TI__Expert 8365 points

    Eduardo,

    This is correct. For Li-Ion, you should discharge at a C/10 rate down to the minimum voltage as specified by the cell manufacturer.

    Thanks,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    Intellectual 420 points

    Thanks Jackson. We´ll do the process this way then:

    1. Place 2x 18650 batteries on our board (circuit on 1st post) and fully discharge them.

    2. On bqStudio, connect to BQ28Z610 of our board and make sure CHG and DSG of OPERATING STATUS A are set.

    3. Let it all rest this way for 2 hours.

    4. Connect the USB cable to our board to charge the batteries and then click START LOG on bqStudio.

    5. Once the batteries are fully charged (no more current shown on bqStudio), we´ll unplug the USB and let them rest for 2 hours.

    6. Then connect our discharge circuit to the output connector of our board (SYS pins of BQ25883) to discharge the batteries with constant C/10 current.

    7. Once the batteries reach minimum voltage, we´ll stop discharge and let them rest for 2 hours.

    8. Then, stop logging, and submit the files to the online GPCCHEM tool.

    9. Once received response, program the closest chemistry to the BQ28Z610.

    Do you believe it´s all correct?

    Thanks,

    Ed

  • 0 in reply to Eduardo Barcellos
    TI__Expert 8365 points

    Hi Ed,

    This procedure should be correct. I will mark this thread closed but feel free to open a new one if you run into any issues.

    Best Regards,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    Intellectual 420 points

    Thanks for all your help Jackson. We'll try this procedure.

    Ed