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BQ40Z50-R1: How to learn calibration for SOH

Cherry Zhou
Mastermind 22235 points
Part Number: BQ40Z50-R1

Hi team,

The SOH load rate is set to 5, 0.2C charge and discharge, and then the ratio of SOH FC@25C Q to design capacity is SOH, 91%. The customer has the following questions:

1. SOH FC@25C Q is related to what states?

2. How to learn SOH FC@25C Q very close to the design capacity, ratio is close to 1?

3. Does SOH FC@25C Q change with charge and discharge? Is it continuously falling or changing?

Could you help check this case? Thanks.

Best Regards,

Cherry

  • 0
    TI__Genius 10370 points

    Cherry,

    1) SOHFCC_mAh is the results of the impedance track simulation. The difference between SOHFCC and FCC is SOH forces the sim to be at 25degC and C/5 discharge rate. So as the battery ages QMax will go down and resistance will go up. Thus SOHFCC will go down. 

    2) You would need to modify your design capacity to set the initial SOH % you would want. The bq40z50-R4 Firmware has a new feature to learn the "max value" SOH FCC is so every battery will start at 100%. 

    3) Yes SOHFCC is re-simulated every time FCC is re-simulated. I would not expect it to change very rapidly unless there is a change in QMax or Ra table. The biggest learning point is when you program in a golden image into a different battery. You could see some delta there as the new battery is learned by the gauge. 

    Thanks,

    Eric Vos