BQ78350-R1A: I'd like to know how to let the part learn SOC faster.

Hello Makoto Teramoto,

CEDV gauges have a production flow as follows.

1.Identify the gauge based on application

     - Determine if system or pack-side IT gauge.

- Use system side gauge if the battery is detachable and pack-side if the battery and the gauge will always be attached together.

2. Calibrate the voltage, current , temperature measurements, cc offset and board offset if available

  - Set up the environment as shown

  - Use bqstudio to perform V,I,T

  and cc-offset and board offset calibration

3. Configure the data memory parameters referencing the technical reference manual(TRM). Most important parameters are:

-   EDV2, EDV1 and EDV0 corresponding to 7%, 3% and 0% SOC at room temp.

-Taper current. Values between C/10 and C/20 should be used.

-Discharge current threshold. This should be less than taper current

-Charge current threshold. This should be less than taper current.

-Quit current. This determines the gauge’s relaxation state. This value should be less that dsg and chg current thresholds and less than or equal to C/20.

-Design capacity: Rated Nominal capacity of the cell.

-Design voltage: Rated Nominal voltage of the cell.

-Charging voltage.

4. Perform a learning cycle
   
   • 6 different cycles are required for this test while logging V, I, T.

   Discharge from full to empty using the typical high rate of your application at room temperature (25oC)

   Discharge from full to empty using the typical low rate of your application at room temperature (25oC)

   Discharge from full to empty using the typical high rate of your application at high temperature your application will see(typically 50oC is used)

   Discharge from full to empty using the typical low rate of your application at high temperature your application will see(typically 50oC is used)

   Discharge from full to empty using the typical high rate of your application at low temperature your application will see(typically 0oC is used)

   Discharge from full to empty using the typical high rate of your application at low temperature your application will see(typically 0oC is used)

   • Submit the files to gpccedv
   • Program the returned 7 CEDV coefficients (EMF, C0,R0, T0, R1, TC, C1) in the gauge

5. Extract golden file

   • The golden file is extracted using bqstudio.
   • It could be srec which is a standard Motorola format file.
   • It could be flashstream file:bqfs or dffs. Bqfs contains the instruction flash and data flash while dffs contains only the data flash parameters.

6. Evaluate accuracy at room and low temperature with actual load profile

   • Coulomb count the passed charge from full to empty to get the true FCC.
   • Calculate the remaining capacity by subtracting the sum of the charge out battery from the true FCC.
   • Calculate the true SOC by dividing the remaining capacity by the true FCC and compare that to what the gauge reports.

Regards,
Jose Couso