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CCS/BQ40Z60: bq external temp reading jumps ata the beginning of discharge and charge

Emma Wang_DELL EMC
Intellectual 695 points
Part Number: BQ40Z60
Other Parts Discussed in Thread: BQ27510-G3

Tool/software: Code Composer Studio

Hi TI:

     My current BQ is BQ40Z60. NTC is 10k(Thinking DHT0A103F34D2SY, R tolerance=1%, B tolerance=2%).FW for temperature is like below table. Schematic and layout picture are attached.  I attached test data. I tested temperature in 50C ambient temperature with discharge current about 10A. However, temperature is abnormal. there was temperature jump about 4C at the beginning of discharge. And there was large deviation about 12C between BQ temperature reading and reading(thermal couple reading). There was temperature fall at the beginning of charge. My question is how to avoid temp jump or fall when discharging and charging. Could you give me some advice?11191648_120W_50_useful.log.xlsx

Thanks!

6254.BQ40Z60.pdf

Calibration Temperature Internal Temp Offset 0 degC
Calibration Temperature External1 Temp Offset 0.7 degC
Calibration Temperature External2 Temp Offset 0 degC
Calibration Temperature External3 Temp Offset 0 degC
Calibration Temperature External4 Temp Offset 0 degC
Calibration Internal Temp Model Int Gain -12143 -
Calibration Internal Temp Model Int base offset 6232 -
Calibration Internal Temp Model Int Minimum AD 0 -
Calibration Internal Temp Model Int Maximum Temp 6232 0.1degK
Calibration Cell Temperature Model Coeff a1 -11130 -
Calibration Cell Temperature Model Coeff a2 19142 -
Calibration Cell Temperature Model Coeff a3 -19262 -
Calibration Cell Temperature Model Coeff a4 28203 -
Calibration Cell Temperature Model Coeff a5 892 -
Calibration Cell Temperature Model Coeff b1 328 -
Calibration Cell Temperature Model Coeff b2 -605 -
Calibration Cell Temperature Model Coeff b3 -2443 -
Calibration Cell Temperature Model Coeff b4 4696 -
Calibration Cell Temperature Model Rc0 11703 -
Calibration Cell Temperature Model Adc0 11703 -
Calibration Cell Temperature Model Rpad 0 -
Calibration Cell Temperature Model Rint 0 -
  • 0
    TI__Mastermind 24870 points

    Hello Emma,

     

    That is when you applied a high current. There is a gap of 4 seconds in the logging, please switch to 1 second logging and re-run the test to see if the delta is slightly smaller. You are applying quite a large current, so it may be that the cell is heating up fairly quickly at that point.

  • 0 in reply to Kang Kang
    Intellectual 695 points

    Hi Kangkang:

         I will change to 1s logging and test again. But I suppose this is because ground of  NTC will be impacted when discharging or charging. And I also used thermocouple  to test. But there is no jump or fall when using 4 seconds logging and it was smoothing. So I don't  think it is because there is large heating up. I experienced similar problem in BQ27510-G3. The method to solve in BQ27510-G3 is to move to stable ground instead of negative point of battery. So i am curious about is this same problem? I did apply  in a large discharge current that is my application. So I think there is no way to change. Could you help to give me some advice to avoid temp jump or fall?

    Thanks!thermocouple test data.xlsx

  • 0 in reply to Emma Wang_DELL EMC
    TI__Mastermind 24870 points

    Hello Emma,

    I would recommend to lower the terminate voltage if you are able to in your system?

    The other suggestion is to make sure you ran a learning cycle. Can you attach your srec or gg file here?