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BQ76930: BQ76930

Part Number: BQ76930
Other Parts Discussed in Thread: BQ78350-R1A, , MSP430FR6989

Hi, 

I am considering to use the BQ76930 cell battery monitor for a configuration of parallel cells, I want to use it with the BQ78350-R1A to form a complete BMS.

I would like to know if it is possible to connect several BMS (built with the previous components plus a companion controller) in parallel to control each combination of packs which are going to be connected in parallel. I attach an image to be more comprehensive.

I don't want to use only one BMS for all the structure because it would require to connect all the internal points of the series cells, so for that reason my question is more related to use several BMS in parallel, with the intention that each BMS controls only a branch.

Do you consider that is needed to add a blocking diode to protect each pack?

Thanks in advance. 

  • Hi Jose,

    It is theoretically possible to have multiple packs in parallel, but we don't have any documentation for how to achieve this. The main concern that I can think of is that if the stack voltage varies between the packs, then one pack will begin charging the others.

    A blocking diode on PACK+ or PACK- wouldn't be a very robust solution as it would function to prevent the packs from interacting with each other, but it would also prevent charging from a charger as well.

    Regards,

    Max Verboncoeur

  • Hi Max Verboncoeur,

    Thanks for your answer. I have more questions related with the communication between the BQ7835-R1A and my main controller (MSP430FR6989):

    - 1.- Can I make the connection directly between the SMBus pins of the BQ7835-R1A and the I2C pins of the MSP430FR6989 or I need extra hardware or software to do that? Do I need to adapt the pull up voltage level?

    - 2.- Can I connect the pull up resistor of the SMBus (BQ7835-R1A) to a 3V3 level?

    - 3.- Can I use the SPI pins of MSP430FR6989 to communicate with the SMBus of the BQ7835-R1A? If it is possible how can I do it? Do I need specific hardware?

    Thanks in advance. 

  • Hi Jose,

    I recommend that you create a new thread for new questions regarding a different device, that way the questions can be quickly assigned to the correct team and the thread is more visible to anyone who may have the same or similar questions in the future.

    Regards,

    Max Verboncoeur