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Original question:

BQ76952: Host Cell Balance problem

BQ76952: Host Cell Balance problem

Zhang Gong
Prodigy 190 points
Part Number: BQ76952

Tool/software:

Dear Ti，

We have an issue with host cell balance，When i use 0x0083 CB_ACTIVE_CELLS() command to strart balancing,i found the cell volt data collectes by bq76952 become incorrect,show as follow image:

The control logic is to balance non-adjacent cells that meet the balance conditions every 1s,as bit set 0x55555555 or 0xAAAAAAAA.

The schematic show as follow image:

Looking forward to you reply.

Best wish

  • 0
    TI__Genius 17835 points

    Hello Gong,

    Thank you for sharing your schematic and data/images. Section 2.5 Voltage Measurement Accuracy During Balance in the Cell Balancing with BQ769x2 Battery Monitor Family application note may help explain some of the inaccuracies you are seeing.

    I think smaller resistors may potentially help in your case as we personally recommend a maximum input resistor value of 100 ohms.

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 190 points

    Hi Alexis，

     Thanks for reply ，I think that now my circuit has been designed exactly according to the manual and meets the requirements, but this does not seem to solve the issue; And the voltage error is more than 100mv, not about 10mv mentioned in the instruction manual. What other aspects do you think might be contributing to this issue?

    Best wish

  • 0 in reply to Zhang Gong
    TI__Genius 17835 points

    Hello Gong,

    Can you please share with me your .gg file as well to take a look? 

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 190 points

    Hi Alexis，

    Sorry for the late reply,I was back from my holiday. And here is the .gg file.

    configuration1.gg.csv

    Best wish

  • +1 in reply to Zhang Gong
    TI__Genius 17835 points

    Hello Gong,

    Hope you had a nice holiday! Thank you for sharing your .gg file. I noticed that in VCELL_MODE (Settings:Configuration:Vcell Mode), you only enabled Cell 1 to Cell 9, and Cell 16, however, on your schematic, you are using VC0 to VC11 and VC16.



    Please try enabling all the correct cells and see if that helps. Vcell Mode is important in disabling protections as well as telling the part, which cells are adjacent during balancing, so it knows which channels to turn off.

    Best Regards,
    Alexis