• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 62 subscribers
  • Views 202 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ76952: Battery balance problem

Zhang Gong
Prodigy 190 points
Part Number: BQ76952
Other Parts Discussed in Thread: BQSTUDIO, EV2400

Hello experts!
I had some problems with the BQ76952's cell balance function. When I use the host-controlled cell balance, I use the command 0x0083 to write 0x0001 to turn on the balance of the second cell to meet the voltage difference of 40mV. At this time, the voltage of the first section will increase by a lot, about 2000mV, and the second section will decrease by 2000mV, which will not happen after closing the balance. I would like to ask what causes this. The following is my configuration and part of the schematic diagram, please help me to check if there is any problem.
1, balan cfg: 0x08,
2, balance Max cells: 0x08
3, cell balance Interval: 0x16
4, cell balance min cell temp: 0x05
5, cell balance max cell temp: 0x50
6, cell balance config: max internal temp: 0x504530.16S_AFE Circuit.pdf
7, [loop_slow][CB_loop_slow] is set to 1/8
8, power cfg: 0x0040

  • 0
    TI__Mastermind 25980 points

    Hi Zhang,

    Do you have a waveform showing this? Also, writing 0x0001 to 0x0083 should start balancing on the first cell, not the second, which may be why you're seeing the cell voltages changing in a way you don't expect. 0x0002 would start balancing on the second cell.

    One thing I noticed in your schematic that may be unrelated is that R121 is recommended to be 0-Ohms. The B0 node, or the negative terminal of the bottom cell should be directly to VSS.

    Regards,

    Max Verboncoeur

  • 0 in reply to Max Verboncoeur
    Prodigy 190 points

    Hello! MAX
    Thank you for your answer, and this issue has been resolved, I have another problem, but I have a short turn on and off problem when I use the command to control the FET shutdown (this does not happen if the FET is shut down due to a fault trigger). Below is my relevant configuration and oscilloscope screenshot, please take a look at this problem. Thank you!
    CFETOFF_config 0x02
    DFETOFF_config 0x02
    DCHG_config 0x00
    DDSG_config 0x00
    FET_CHG_PUMP_CONTROL 0x05
    FET_OFF_DELAY 0x00
    pretect config 0x0000
    When I use the command to control the FET, I first check if FET_EN is 1, if it is not 1, I send 0x0022, and then send the command 0x0097 and send the corresponding bit to turn on or off the corresponding FET.

  • 0 in reply to Zhang Gong
    TI__Mastermind 25980 points

    Hi Zhang,

    Can you monitor the Battery Status (0x12), Alarm Raw Status (0x64), and FET Status (0x7F) registers and take a log of their values while this behavior is occurring? Also, if you are using or have access to an EV2400, using bqStudio to take a log and export a .gg config file would also help.

    Regards,

    Max Verboncoeur