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BQ34Z100: The taper current setting problem

Teresa Chiu
Prodigy 690 points
Part Number: BQ34Z100

Hi expert,

My customer meet some problems on the taper current setting. This validation is based on the EVM with K2B24V10EB battery test.

Could you help to check is there any setting is wrong?

1. FC Flag behavior is not consistent with taper current setting,

Taper current is set at 200mA, but FC FLAG will change from 0 to 1 when current decrease to 1447mA.

2. The FC flag is high(1), but the charging current is not zero.

20190919.gg.csv

CHARGE-20191016.xlsx

  • 0
    TI__Genius 12215 points

    Teresa

        Please set FC Set to -1, RMFCC in configuration register to 1

  • 0 in reply to Steven Yao
    Prodigy 40 points

    Hi Steven,

    Thanks for the quick response.

    As you can see the attached gg file, we've tried the gauge setting as you recommend.

    The RMFCC bit is set as before, the only difference is FC set% change from 100 to -1.

    But it seems doesn't work.. Is there any mis-understanding or do you have further suggestion?

    1. FC Flag behavior is not consistent with taper current setting.

    2. The FC flag is high(1), but the charging current is not zero.

    EMA-CHARGE5A FC CHECK -20191107.xlsEMA-GG-20191107.gg.csv

  • 0 in reply to kim Wang
    TI__Genius 12215 points

    Hi, Kim

        I see in your log file, the FC is set in this line:

    1669 11/7/2019 11:05 8346.059 0x0016 0x0003 100 10952 10952 29232 176 180 79 100 29200 4800 0x09E3 0x2280

       The current already tapered to 176mA, which is exact 80s(2 consecutive current taper window) after the current approaches to 200mA.

       The SOC is rounded up to 100% when it pass across 98.984% to 99.03%, this is a round up issue.

       The reason for SOC stays longer at 100% before FC bit is set is because of the current was tapering down after SOC rises above 99%

  • 0 in reply to Steven Yao
    Prodigy 40 points

    Hi Steven,

    FC sets to -1 seems works when taper current approaches 200 mA.

    But we are wondering if there would be any side effect when TCA Set % set to -1.

    Because when 99% change to 100% the flags change from 0x2180 to 0x2080. Which means there will be almost 10 min not charging before FC set to 1 (0x2280).

    Another issue we found is that after FC set to 1 the charging curent doesn't report 0. Could you provide some suggestion?

    Kim. 

    4645.EMA-CHARGE5A FC CHECK -20191107.xls 

  • 0 in reply to kim Wang
    TI__Genius 12215 points

    Hi, Kim

        The bq34z100G1 is a pure gas gauging device, it does not control a physical charge and discharge path of the battery pack, the host may access the desired bit in bq34z100G1 to determine whether to charge or stop charging.

       For your case, the host can read FC bit and terminated charging when FC is set.

       TCA bit only affect CHG bit to be on of off.

       Charging current is a function of temperature defined as JEITA T1 to JEITA T4 in datalflash. FC bit does not affect Charging Current regsiter