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BQ78350-R1: mWh reading

Needhu Gunasegaran
Intellectual 2890 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76930, BQSTUDIO

Hi Team,

Could you please answer the following question from the customer.

In a current project we use the bq78350-r1 together with a bq76930.

Unfortunately, reading the mWh (0x10 FullChargeCapacity) does not work. The designed capacity is always displayed.
If the register is switched to mAh with CAPM = 0, the mAh will be displayed correctly.

Can you explain how we get the mWh displayed correctly?

Thanks,
Needhu

  • 0
    TI__Guru 54715 points

    Hi Needhu,
    By default the design capacity mAh is the same as the Learned FCC, 4400 mAh.
    The design capacity cWh is 6336 which corresponds to the default voltage x the default capacity x 4 cells, although the default is 3 cells.
    If you set CAPM you read 47520 mWh, and you can't tell if it is using Learned FCC or design capacity.

    If you change the Learned FCC the result appears the same.  To get FCC (command 0x10) to report the proper value you must send a reset so that it uses the new value.  Then changing CAPM changes the reported value from mAh to cWh.  If the gauge is running and learns, it will have the updated value and will calculate correctly, no reset is expected or needed.

    Hi Needhu,

    I edited above to correct the unit.  bqStudio displays mWh but command 0x10 reports cWh.