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BQ34Z100: Accuracy of the Impedance Track algorithm in 14S configuration

Pietro Vignali
Intellectual 925 points
Part Number: BQ34Z100
Other Parts Discussed in Thread: BQ40Z50, ,

Hello,

we have already managed to design and work with other impedance track gauges (bq40z50) and we understood that for the accuracy of the algorithm the gauge monitors the single cell voltages to detect their voltage drop at rest and under load in different temperature and load scenarios.

We are now designing a 14S pack and since we want to implement the Impedance Track algorithm we are currently evaluating the usage of bq34z100 (or g1).

Looking at the documentation I notice that the bq34z100 does not monitor the single cells, but only the pack voltage.

Is the Impedance track algorithm somehow less accurate because of the lack of the single cell voltage details ?

Thanks and regards

Pietro

  • 0
    TI__Guru** 105770 points

    Hello Pietro,

    The same algorithm is used for both gauges, the bq34z100-g1 will divide down the top of stack voltage to simulate for the number of cells used. This prevents the gauge from having any safety alerts for cell imbalances. The algorithm should perform well with either gauge, the bq34z100 just has less functionality due to the top of stack method for high cell counts.

    Most of the Impedance Track accuracy depends on the learning cycle and the chem ID used.

    Sincerely,

    Wyatt Keller 

  • +1 in reply to Wyatt Keller
    Intellectual 925 points

    Thank you Wyatt, it is more clear now.

    The application is an ebike battery pack where we do not expect a continuous discharge current but rather a fluctuation of the discharge current, with continuous pulses of different amplitude and frequent relax moment.

    Considering that the chem ID of the cells we will use is already available in the chemDB, do we need to process a particular learning cycle to obtain an accurate golden image for the bq34z100, or the usual method already used for other gauges as explained in your several application noted (like for instance for the bq40z50R2) fits well ?

    Thanks in advance

    Pietro

  • 0 in reply to Pietro Vignali
    TI__Genius 11535 points

    Hi Pietro,

    You will need to run a learning cycle for your own application using the method outlined in our application notes

    Best,

    Jessica