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Original question:

BQ34Z100-G1: Learning Issue

BQ34Z100-G1: FCC- wrong value

Avi shavit
Intellectual 510 points
Part Number: BQ34Z100-G1

Hello

I  peogramed golden file to a new battery.

The actual capacity i measured is 17.6AH

i have done 3 cycles, in each cycle i got higher FCC

after 3 cycles i get FCC=18.1AH

why is that?

attached the GG file

Regardsgg file bat 8.gg.csv

  • 0
    TI__Guru 52115 points

    Hi Avi,

    How did you get the actual capacity?  FullChargeCapacity(FCC) is the usable capacity of the battery from full to empty. The Impedance Track algorithm applies QMax, impedance, temperature, voltage, and current data to predict the runtime FCC. It will be updated when a QMax update occurs and also during discharge. 

    Andy

  • 0
    TI__Genius 12215 points

    Hi, Avi

        Once the gauges undergoes learning cycle successfully, the update status should be 0x6, which applies limit to Ra and Qmax Update, please refer to the specific limit defined in data flash.

        Due to the limit applies, the Ra and Qmax approaches to the real target value gradually during a couple of beginning cycle for a new battery. I think this is why you see FCC changes gradually in first 3 cycle when you download the golden files to a new battery.

  • 0 in reply to Steven Yao
    Intellectual 510 points

    Hello Steven

    my problem is not that the gauges approaches gradually. my problem is that the FCC at the golden pack is 17.35AH and after 3 cycles this battery gradually increased to 18.1AH although the real capacity (which was measured by external equipment) is just 17.6AH.

    i expected that the FCC will stabilized arround 17.6AH, which was after the first cycle and not continue to rise.

    The update status is indeed 0x6.

    Regards

    Avi

      

  • 0 in reply to Andy Liu (BMS)
    Intellectual 510 points

    Hi Andy

    I got the actual capacity by measuring the capacity from full to empty (empty- according my application) by External equipment.

    Avi

  • 0 in reply to Avi shavit
    TI__Genius 12215 points

    Avi

       I think I have understood your question, actually I mean that the Qmax and Ra would approach to the real value from cycle to cycle, instead of only one cycle, because these values are applied with a filter so that they would change to real value from cycle to cycle instead of only after first cycle. As the Update status has already been 6 when you download the golden file to the target device and enabled IT algorithm.

  • 0 in reply to Steven Yao
    Intellectual 510 points

    Steven

    the real battery capacity is 17.6AH

    FCC after golden pack programing= 17.35AH

    FCC after cycle 1= 17.6AH

    FCC after cycle 2= 17.8AH

    FCC after cycle 3= 18.1AH

    from cycle to cycle it moves away from the real capacity.

    why is that?

  • 0 in reply to Avi shavit
    TI__Genius 12215 points

    Avi

        OK, how do you measure the capacity of the target battery? is this capacity all the same for 3 discharge cycles?

        When you measure the capacity, how did you measure the current? By a DMM or by reading data from the gauge?

       

  • 0 in reply to Steven Yao
    Intellectual 510 points

    I measured the capacity with dedicated and calibrated equipment for capacity measurement (ARBIN).

    the capacity measurement is the same for all 3 discharge cycles.

  • 0 in reply to Avi shavit
    TI__Genius 12215 points

    Can you check if the current measured by the gg if accurate, if the current is measured higher by gg, then the capacity measured by gg can also be high

  • 0 in reply to Steven Yao
    Intellectual 510 points

    yes, the current measured by gg accurate

  • 0 in reply to Avi shavit
    TI__Genius 12215 points

    Avi

        Can you check how accuracy the current measurement is at different level current? also please check if the delta of passed charge from beginning to end of the discharge 

  • 0 in reply to Steven Yao
    Intellectual 510 points

    the diffrent between Equipment current to gg current is 0.3%

    regarding the other thing i'll check it latter and let you know

    could you check the gg file i have sent you?  if you see somthing suspicious

  • 0 in reply to Avi shavit
    TI__Mastermind 24870 points

    Hello Avi,

    Nothing stands out. Have you looked at SOC accuracy? As long as SOC is accurate, FCC may be slightly high based on some overestimation in the smoothing engine. Make sure to check FCC Unfiltered as well.

  • 0 in reply to Kang Kang
    Intellectual 510 points

    Hello

    question regarding few parameters at Data Memory

    Design Energy should be Design capacity* 1 cell voltage or pack voltage?

    If it's 1 cell voltage so it should be =6300 while in my design it's 5400- can it cause to my problem?

    I saw few parameters in my design at IT CFG in Data memory which are not the same as the default value

    Max Res factor= 15 while default= 50

    Min Res Factor= 3 while default= 1

    Design Resistance= 210 while default= 42

    can it cause to my problem ?

    Best regards

  • 0 in reply to Avi shavit
    TI__Mastermind 24870 points

    Hello Avi,

    No, that has nothing to do with the A/D measurements.

    These are parameters for resistance update filters.

    Can you look at SOC accuracy?

  • 0 in reply to Avi shavit
    Intellectual 510 points

    Hello

    Do you have answer to my questions from 5/3 ? see below the question regarding Thia issue

    Hello

    question regarding few parameters at Data Memory

    Design Energy should be Design capacity* 1 cell voltage or pack voltage?

    If it's 1 cell voltage so it should be =6300 while in my design it's 5400- can it causes to my problem?

    I saw few parameters in my design at IT CFG in Data memory which are not the same as the default value

    Max Res factor= 15 while default= 50

    Min Res Factor= 3 while default= 1

    Design Resistance= 210 while default= 42

    can it cause to my problem ?

    Best regards

  • 0 in reply to Kang Kang
    Intellectual 510 points

    Hello

    SOC Accuracy= 0.9%

    this is the difference SOC in % between gg SOC to external Equipment SOC at discharge

    SOC measured each 4 sec during full discharge

  • 0 in reply to Avi shavit
    TI__Mastermind 24870 points

    Hello Avi,

    It seems like the gauge is fairly accurate. It brings me back to the original point, there's no need to worry about FCC accuracy. You could try to read FCC Unfiltered to see if that's accurate.