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BQ34Z100-R2: Using System-Side and Pack-Side Fuel Gauges at the Same Time?

Part Number: BQ34Z100-R2
Other Parts Discussed in Thread: BQ25750, BQ40Z60, BQ34Z100

Tool/software:

Good Afternoon,
I am working on a battery-powered device that utilizes an OTS battery pack. System-side, I will be implementing a battery fuel gauge (BQ34Z100-R2) and charging circuit (BQ25750).
I am not intimately familiar with the internal structure of our OTS battery pack, but am aware that it also utilizes an integrated management system/fuel gauge, BQ40Z60, that I have the option of interfacing with. The reason for having two fuel gauges in my design now is that, in the future, we may switch to a different OTS battery that does not have an integrated manager.
My question: Is it acceptable to operate my device with a pack-side BQ40Z60 and system-side BQ34Z100-R2 present at the same time? What about a pack-side BQ40Z60 and system-side BQ40Z60 at the same time? Will the performance of both fuel gauges remain uncompromised? What sorts of things will I need to consider when implementing my design that are unique to this type of setup?

Thank You!

  • Hi,

    The BQ34z100 is a top of stack fuel gauge that does not cell balance or have any protection. In order for the gauge to function properly the cells need to be balanced. Ideally our gauges should all be pack-side and "married" to the battery, this is so the gauge can learn parameters specific to that particular cell. 2 fuel gauges, system and pack side, should not affect each other.

    Regards,

    Evan