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Original question:

BQ76952: Cell Balancing

BQ76952: Host Balancing

Phil Eagleton1
Prodigy 30 points
Part Number: BQ76952
Other Parts Discussed in Thread: BQSTUDIO

Hi,

After finding out the hard way that balancing was disabled in early parts, we have bought and reworked with new parts. We are still struggling with balance control, and when sending a cell number to balance to the device (0x0083) the device returns 0x0000 immediately, and the cell balance counter does not increase.

Please can anyone help me understand the logic, and protections that might be in place to prevent balancing working? I have ensured that voltages are OK, temperature are within limits and even set all protections OFF. 

Please help... starting to feel like this silicon is also faulty.

Thanks

  • 0
    TI__Expert 5090 points

    Hi Phil,

    For starters, can you confirm the version of the device you have now?  You can run the FW_VERSION() command and see what it returns.

    Are you using bqStudio or your own host?

    Make sure you are writing the two bytes into 0x40 and 0x41, then writing the correct checksum and length into 0x60 and 0x61.

    Thanks,

    Terry

  • 0 in reply to -Terry
    Prodigy 30 points

    Hi, I have my own board, which I have connected to the bqstudio via I2C, and I am currently using BQ Studio to experiment with the settings on my PCB.A screen shot from BQStudio is below, FW Version = 36.

    To try and invoke balancing I am writing 0x0001 into the cell active balancing on this page, by double clicking the value and then pressing enter. Is this not the correct way to load this value?

    Thanks,

    Phil

  • 0 in reply to Phil Eagleton1
    TI__Expert 5090 points

    Hi Phil,

    I hadn't tried doing it that way in bqStudio - we don't have many subcommands that can be written with data.  I tried your way and it doesn't seem to be working for me, this may be a bqStudio limitation.  I was using the command sequence tab, to send the subcommand address and data to 0x3e, then the checksum and length to 0x60/61, this way works for me, you might try this approach instead.  Note that to use this you should disable the Auto Refresh (top left of Dashboard page) and disable scanning of the registers (top right of register page), so bqStudio isn't sending transactions between your separate I2C transactions. After sending the sequence, you can manually hit the "refresh" button on the register page to see if the update took.

    Note that you may want to set Settings:Cell Balancing Config:Cell Balance Interval to a long number, such as 255-sec, so it doesn't timeout before you have time to check it.

    Thanks,

    Terry

  • 0 in reply to -Terry
    Prodigy 30 points

    Hi Terry,

    I have run some tests here. I can confirm that sending the balance command using the subcommand write in the command sequence works correctly, and I have successfully run a cell balance.

    In summary - the option to enter a register value on the main screen of BQStudio does not work. You have to enter values using the subcommand sequence.

    Thanks for your help,

    Phil