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BQ79616: Establishing Daisy Chain Links for BQ79616 in Parallel Battery Branches

sridharan padmanabhan
Prodigy 30 points
Part Number: BQ79616

Tool/software:

Hello Experts,

Our team is developing a battery management system for a 10 kWh battery pack using the BQ79616 chip.

According to the datasheet, each BQ79616 module can be connected in a daisy chain configuration. To increase the storage capacity, we have added two additional branches in parallel.

Could you please advise on how to establish the daisy chain link between the BQ79616 modules in these parallel branches?

Additionally, please refer to the attached block diagram and confirm if the daisy chain connection shown is achievable with this chip.

Thank you,

Best regards,

Sridharan

  • 0
    TI__Mastermind 42060 points

    Hello Sridharan,

    Instead of using a MCU(BMS), we would recommend to use the BQ79600 bridge device, which provides galvanic isolation between the low-voltage components and the high voltage battery packs. You can communicate with SPI or UART directly through the bridge device. 

    If you prefer having CAN architecture instead, then your architecture is fine.

    Regarding the daisy chain in parallel, this is not something that we have ever seen before. Usually when cells are in parallel a single AFE string is needed, there is no need to have multiple in parallel.

    We would not recommend this configuration.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 30 points

    Hi Luis,

    We prefer to use an MCU (BMS) to process and convert cell data into CAN (or MODBUS) and then transfer it to the Master MCU located at a distance. We will consider the communication bridge interface circuitry as you suggested.

    Regarding the daisy chain linking of parallel branches, do you mean that the BQ79616 daisy chain link is only needed on one of the branches instead of all? If so, we are curious about how the cells in the other branches are monitored. 

    Thank you,

    Sridharan

  • +1 in reply to sridharan padmanabhan
    TI__Mastermind 42060 points

    Hello Sridharan,

    sridharan padmanabhan said:
    Regarding the daisy chain linking of parallel branches, do you mean that the BQ79616 daisy chain link is only needed on one of the branches instead of all? If so, we are curious about how the cells in the other branches are monitored. 

    A single monitor is very common to monitor many cells in parallel, even for non-stackable monitors. When the cells are in parallel, their voltages are shared and you would be able to monitor all of the parallel cells at the same time. It would just appear as a larger capacity cell to the monitor.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 30 points

    Hi Luis,

    Thanks for the clarification. 

    Best regards,

    Sridharan