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BQ27742-G1: Chem ID Configuration and Cold Temp

JDJ
Expert 3171 points
Part Number: BQ27742-G1
Other Parts Discussed in Thread: GPCRB, BQSTUDIO

Hello, 

We have a few questions regarding the BQ27742-G1 after recently getting our Chem-ID from TI.

  1. After updating the chemistry, there was a prompt to update the ‘target bqz container’ (see attached ‘ChemID-Update-Screenshot’). Will this affect the FG config in any way? How do I go about updating the bqz container?
  2. Is there a need to run any learning cycles once the chemistry is updated? What is the procedure?
  3. There appears to be an issue with tracking capacity and SoC correctly at cold temperature (-20C) as shown in the attached picture ‘TI_FG_ColdTempPerformance’. We are using the Arbin capacity as our baseline for comparison. How do I go about calibrating the FG for better low temp. accuracy? Will this improve with learning cycles? We came across the GPCRB tool but are unfamiliar with the procedure. Is this needed for better tracking at cold temp?

Thanks!

  • 0
    TI__Guru 51466 points

    #1: Please update bqStudio from https://www.ti.com/tool/BQSTUDIO. This will have the latest bqz.

    #2: Was this a ChemID that was created by TI for your cells (=the cells were shipped to TI by you) or was this a ChemID that you found by make/model? If it's a new ID from TI then you don't need a full learning cycle for cell resistance (though you need to make sure that Qmax is set correctly, which is not part of the ChemID). For practical purposes, at least a Qmax update is necessary in a shortened learning cycle.

    #3: The ChemID may not be optimized for -20deg.C. Please perform the steps from GPCRb. The output from GPCRb is an updated ChemID (a .chemdat file) and an updated .gg file with updates to the thermal model. Note that it is critical that the instructions in the user's guide for GPCRb are followed with utmost care. It's particularly important that the temperature measurement reflects what happens with the cell at low ambient temperature (e.g. -20deg.C) in your actual product (not just the naked cells) without a temperature chamber blasting -20deg.C air onto the cells. The idea is that GPCRb learns how cell resistance and self heating in your product (in the enclosure with its temperature isolating behavior) changes during a discharge when the ambient temperature is -20deg.C.

  • 0 in reply to Dominik Hartl11
    TI__Expert 3171 points

    I really appreciate the quick and detailed response! 

    The ChemID was created by TI, is -20C a part of the TI FG characterization process? 

    Thanks!

  • 0 in reply to JDJ
    TI__Guru 51466 points

    I just checked. ChemID 5682 was done at 0deg.C, 25deg.C and 50deg.C.

    For -20deg.C, GPCRb and possibly a manual tune may be necessary. It's also critical that the Temp k/a settings are correct. The gauge will learn these over time assuming that the cell resistance values at the measured temperatures are correct.