• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 295 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Initial charge on batteries for bq27541 = ?

Wally Lowry
Prodigy 230 points
Other Parts Discussed in Thread: BQ27541

Hi, I am trying to get my arms around all the details of the process before implementing the design of a BQ27541 (GG). I've read SLUA504 (Going to Production With the bq2754x) and I understand the testing of samples and creating a DFI. I understand that calibration for each board/circuit is optional at production.

The thing I don't understand is how does the bq27541 (GG) find or know the initial capacity of the cell, when it is first connected to the cell?  The cells will vary some on their initial capacity from the cell manufacture as they are installed in the pack with the bq27541.  Cells are not shipped at full capacity.  Their may be a procedure for this, but I haven't seen yet.

Thanks in advanced,

Wally

  • 0
    TI__Genius 14985 points

    The bq27541 will take a voltage measurement (OCV, or open circuit voltage) of the cell when the ENABLE_IT command is sent to the gauge, and periodically again when the cell is fully relaxed.  It will look this voltage up on a table and translate that to a SOC (State-of-Charge in %) and a Remaining Capacity (in mAh).  In between these voltage measurements, it will use coulomb counting, real-time impedance measurements, and internal simulations using impedance tables to track the current SOC, remaining run-time, etc.