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bq34z100g1 optimization cycles with scaling

Peter Upczak
Intellectual 965 points

Hello Gas-gauge experts -- 

I now realize that I need to scale my amp readings to fit 90A into the '34z100 clamp at 32.767A. So, a couple of questions:

(1): when I run I.T. optimizations now, should I used the scaled calibration or calibration with no scaling. With no scaling applied, C/10 to C/5 discharge rate is only 1 to 2 amps and a few pennies.

(2): For I.T. optimization, does C/10 result in better data accuracy than C/5 or vice-versa? Or does it matter at all?

thanks! -pete

  • 0
    TI__Mastermind 34775 points

    Hi Pete,

    1. If you're using scaling in your application then run the optimization with scaling.
    2. Choose the one that matches closely to your application. The recommended min is C/10. C/5 is better to take into consideration the self heating of the battery, which is important for IT gauges.

  • 0 in reply to Damian Lewis
    Intellectual 965 points
    Thanks, Damian.
    Since I am scaling only for current, not voltage, are there any other parameters that should be scaled? It's hard to tell for sure from the wording in the docs.

    The LFP26650P pack is 8s4p, 25.6V, 10.4Ah ChemID = K2 Energy LFP26650P (0x401)
    The configuration, data, and IT parameters I use prior to scaling are:
    VOLTSEL=1
    CC gain = 1.50
    CC delta = 1.50
    Design Capacity = 10400
    Design Energy = 3.2v * 2600 = 8320
    CC Threshold = 9360
    Cell Termination Voltage = 2475
    Cell V at Charge Term = 3625
    Initial QMax0 = 10400

    Now with scaling for current, do I need to scale the current-related parameters as well or does the BQ figure it all out for me?
    Cheers! -pete
  • 0 in reply to Peter Upczak
    TI__Mastermind 34775 points

    Hi Pete,

    You have to do design energy scale as well, since your design energy is 3.2V x 10400 > 32767. See page 31 section 7.3.6.5 Design Energy Scale in the datasheet for details.

    The other parameters look ok.