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CCS/BQ40Z50-R1: BQ40Z50R1 chemistry ID error is very big

user6188395
Prodigy 20 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: TEST2,

Tool/software: Code Composer Studio

HI experts!

I measured my battey charge/discharge chemical ID.

My battery pack is 3S28P(10.89v) / 137.2ah.

The single battery model is SAMAUNG inr21700-50e

I measured it two ways.

[Test1] -> single battery manufacturing standard charge and discharge

Charging 0.5c (2450mA) / 0.01c (49mA) stop charging, charging cut-off voltage: 4.25v, rest for 2 hours.

Discharge 0.1c (490mA), discharge cut-off voltage: 2.5v, standing for 5 hours.

[Test2] -> battery pack standard charge and discharge (3S28P)

Charge 0.5c (68600mA) / 0.01c (1372mA) stop charging and rest for 2 hours.

Discharge 0.1c (13720mA), standing for 5 hours.

I put the test data uploaded to www.ti.com.cn/.../gpcchem, TI give chemistry ID error is very big, don't know why?Please teach me.Thank you very much!

In addition, I will attach two kinds of test data.Please review it.

4900mah cell test.zip4900mah cell gpc_chemid_data_test6-report.zip137.2ah 3s28p test2.zip137.2ah 3S28P gpc_chemid_data_test2-report.zip

  • 0
    TI__Mastermind 24870 points

    Hello User,

    Can you try to remove the charge portion and just have the "relax" - "discharge" - "relax" portion in 4900mah_cell_test.zip file?

    The GPC tool tries to parse and remove the charge portion, but I am wondering if that part is getting the wrong parsed portion.

    Thanks for your clear description of the problem.

  • 0 in reply to Kang Kang
    Prodigy 20 points

    Hi kangkang,

    Thank you for your answer. I have found chemical ID 2250
    I have another question. 

    The single battery model is SAMAUNG inr21700-50e（4900mah），28 batteries in parallel

    Total design capacity: 4900mah*28=137200mah, exceeding the bq40z50-r1 requirement of MAX 32767mah Register value, including cwh

    Please help to guide how to solve this problem.

    thank you

  • 0 in reply to user6188395
    TI__Mastermind 24870 points

    Hello,

    That is a very large cell. I'm afraid the only solution we have will drastically reduce gauging accuracy.

    You can technically scale the current such that 1 mA reported is the same as 10 mA, that will reduce 137200 mAh to 13720 mAh, however it may still overflow for cWh computations.

    I am not sure if the sense resistor can handle such a big battery either. What is the level of current you will apply (min and max)