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2 x bq76930 stacking

Tiger Chen
Intellectual 750 points
Other Parts Discussed in Thread: BQ76930

hi, 

can i have 2 separate bq76930 to measure 20 cell battery ?

i am designing bq76930 + mcu in single module which is able to log 10 hours of cell information, and export to pc with csv format, how if i connect 2 modules to 20s battery pack ? 

e.g. the 1-10s battery cell connect to bottom module, and 11s-20s battery cell connect to top module, both module will not link together, in this situation can i still turn on balance feature ? if i set target balance voltage to 3.7v although the cell 1 of top battery pack is not connect to cell 10s of bottom battery pack, can i still use this method to make both pack balance ? any risk i may encounter ? 

thanks,

tiger

  • 0
    TI__Guru 54715 points
    The bq76930 was not designed to stack but it may be possible. If building modules be sure the FETs in each module can support the whole pack voltage. Communication will need to be isolated between your MCU and the common host (PC?) since the 2 modules will be at different voltages.
    If you are not building separate modules but one block, you will need isolation between the ICs and on any interface lines you take between the 2 devices. Your FET driver would need to combine the signals to control the FETs.
    Depending on how you set up your balancing algorithm in the MCU, having the modules balance independently could be OK. You may need some oversight in the host however to recognize if one module is operating at a lower voltage than the other and tell the high voltage module to balance longer.