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BQ40Z50-R1: BQ40z50-R1 in production

Max
Intellectual 940 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQ40Z50

Hi

We have designed  a BQ40Z50-r1 4S1P Battery Pack.

i have done a learning cycle in one pack and extracted the srec file from that pack and uploaded in all the remaining packs

In this the battery is charging to its maximum voltage but i have seen some slight glitches in voltage level. Is it normal behaviour or it should be taken care?

The voltage calibration is done on all packs

Expecting the reply at the earliest.

Attached the log file for refernce.

charge log-24-07-21_srec.log.xlsx

Regards

ANANDAN

  • 0
    TI__Intellectual 2146 points

    Hi Anandan,

    Are you using the EVM? If not it's possible that the hardware could be the cause. It could also be due to the charger or the charging process, since it seems like the glitches stop once the charging winds down and the voltage flatlines. Are you able to see this behavior on discharge also?

    In general though these glitches shouldn't cause much of an issue with the gauge behavior. 

  • 0 in reply to Albert Anwar
    Intellectual 940 points

    Hi Albert

    We have not used EVM. We have directly connected to  Power supply and charged the battery.

    We are not seeing this glitches in Discharge.

    Also I have couple of question 

    1.When charging the battery to maximum set voltage the Battery is charged beyond 16.8V(We have exported the srec file and uploaded in this battery)

    2.After importing the srec file, we need to discharge first or need to charge the battery first??

  • 0 in reply to Max
    TI__Intellectual 2146 points

    Anandan,

    I would suspect that the glitches are caused by your charger, given that they don't happen at times when the battery is not being charged.

    1. Do you have a .gg.csv file and a log for this?

    2. If you are performing a learning cycle then you should follow SLUA903 for instructions. If not the gauge should work for charging or discharging after programming the .srec.

  • 0 in reply to Albert Anwar
    Intellectual 940 points

    Hi 

    Attached the .gg file for your reference. We don't have a log for this sequence.

    During charging the Battery when it reaches the Maximum voltage the tapper current reduces and when it reaches around 114mA the battery changes its current to 94mA.This forms a glitch in the Current waveform.

    The Set Charge Term Current-100mA.

    Also Could you suggest me when to extract the .srec file from the Battery pack.(We have completed the Learning Cycle and also done a charge. When it is fine to extract the srec file during charge or discharge).

    4S1P_SAMPLE-03Rajmane_22-Jul-2021.gg.csv

  • 0 in reply to Max
    TI__Intellectual 2146 points

    Anandan,

    The gauge doesn't control the amount of charging current so you may want to ensure that your charger is providing the correct amount of current. If you have a log I could maybe determine with more certainty whether this is a gauge current measurement issue, but if current measurement isn't an issue in other gauge modes I would say it likely isn't.

    It shouldn't matter when to get the .srec file, so long as the learning cycle is complete.

  • 0 in reply to Albert Anwar
    Intellectual 940 points

    Hi Albert

    Attaching The Log file. The current has  been reduced from 114mA to 95mA.

    4S1P_Sample-11_charge cycle_09-Aug-2021.log.xlsx

    Also we are facing the same glitch issue in another pack when the current is 200mA(CV mode).Suggest a way to solve this issue.

    Regards

    ANANDAN N

  • 0 in reply to Max
    TI__Intellectual 2146 points

    Anandan,

    I don't see any glitches in the voltage or the current measurements in the log you provided. Can you explain what exactly you're seeing?

  • 0 in reply to Albert Anwar
    Intellectual 940 points

    Hi Albert

    In the current u could able to see the glitches, During CV mode at  last the battery current reduces from 107mA to 95 mA directly, We are facing the current(rise and fall) when the current reduces below 500mA.

    Also I have faced another issue ,I have charged the battery to its maximum voltage of 16.8V,But the current does not get reduced. The battery does not follow the CC/CV behaviour. The Overvoltage bit has been set and it is terminated.The Charge current remains at 1A constantly.

    Attaching the log file for your reference..

    4S1P_Sample-05_charge cycle_10-Aug-2021.log.xlsx

  • 0 in reply to Max
    TI__Intellectual 2146 points

    Anandan,

    I couldn't find anything wrong with the gauge concerning the current drop. It's likely your charger that is dropping the current, and the gauge is recording this drop.

    Regarding the overvoltage issue, this is also a charger issue. It's up to your charger to follow CC/CV correctly. The BQ40Z50 can monitor the conditions during charging (such as overvoltage) but it can't make your charger follow exact profiles.

  • 0 in reply to Albert Anwar
    Intellectual 940 points

    Hi

    We have used the Same Setup for some batteries too in that we are not seeing this current glitch at end termination current region.

    2.Regarding the second point we have set 16.8V for charging the battery, but it automatically charges more than the set voltage. Whether it is a calibration issue? How much difference shall arise between the Pack voltage and pin voltage?.

    3.In the gg file whether it is necessary to set the OFFSET taken  bit after the learning cycle process??

    4.We have imported the Srec file from a pack in which the battery behaviour is good, But when we  upload that in a new pack we are seeing the glitches in the current .Also it is necessary to do calibration after importing the srec file on a new pack battery??

    Regards

    ANANDAN N

  • 0 in reply to Max
    TI__Intellectual 2146 points

    Anandan,

    You can try recalibrating and see if that fixes your issue. It shouldn't be necessary to modify the offset taken bit after the learning cycle.