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Original question:

BQ76PL455A-Q1: About the serial communication

BQ76PL455A-Q1: cell failure

user6018308
Prodigy 70 points
Part Number: BQ76PL455A-Q1

I'm using BQ76PL455A-Q1 for measuring cell voltages and cell balancing.

However, certain cells of our battery (cell level / Lithium-ion, 18650, 4.2V, 2.5Ah, assembly level  / 16 series and 4 parallels) was broken at almost 0V.

I still don't know whether or not there is a cause in the IC. so let me know.

Commands we transmit to the IC are as below.

Are there any factors that cause the broken cell to be unbalanced in the following commands ?

 F2 10 10 E0 3F 35
 F1 0E 10 54 5F
 F1 0C 08 55 35
 F1 0A 00 57 53
 81 00 0A 00 2E 9C
 92 00 10 10 20 B4 00
 92 00 10 10 C0 B5 88
 92 00 52 FF C0 59 AC
 91 00 3D 00 3C 6C
 91 00 3E BC 3D 2D
 91 00 07 00 2E CC
 91 00 0D 10 29 A0
 94 00 03 FF FF 01 00 90 7D
 92 00 90 FF FF B9 BC
 92 00 8E 00 00 D8 0A
 91 00 13 08 20 0A
  92 00 14 FF FF F8 69
  92 00 14 00 00 F9 D9
  82 00 14 00 00 38 1A
  81 00 02 00 29 5C
  • 0
    TI__Genius 17370 points

    Hi User,

    Are you using the EVM or custom hardware? Can you test with our GUI or example code to ensure the hardware is working correctly?

    Regards,

    Taylor

  • 0 in reply to Taylor Vogt
    Prodigy 70 points

    Hi Taylor,

    Thank you for reply.

    We used both the EVM and custom hardware.

    At least, there is no unbalanced cell when using the EVM with your GUI.

    When we tested by using custom hardware with the commands shown earlier,

    certain cell of our battery assembly was broken.

    In the initial testing, it looked like working correctly (we could get cell voltages),

    but after several testing, cell failure occurred suddenly.

    So, first we would like to know whether the commands we used was appropriate.

    Please confirm the commands.

    Regards,

    Yoke

  • 0 in reply to user6018308
    TI__Genius 9401 points

    Hi Yoke,

    I recommend starting by debugging the hardware. You can compare the EVM circuit to your custom PCB to check you are following our recommendations. When you are checking this you can also review our recommendations in the "Balancing Circuit" section of the "BQ76PL455A-Q1 design recommendations" document (http://www.ti.com/lit/an/slua791a/slua791a.pdf).

    To identify if the issue is either hardware of software, you can test your board using the GUI for this device and if you don't see the issue anymore then you can focus on the software. If it is a software issue, then please review section 7.3.7 "Passive Balancing" in the device datasheet with the description of the cell balancing function and registers. 

    Best regards,

    Leslie