SLUAAR3 December   2023 BQ27426 , BQ27427 , BQ27Z561 , BQ27Z746 , BQ28Z610 , BQ34Z100 , BQ40Z50 , BQ40Z80

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Voltage Correlation
  6. 3Voltage + IR Correction
  7. 4Coulomb Counting
  8. 5CEDV
  9. 6Impedance Track
  10. 7Algorithm Comparisons
    1. 7.1 Calculating SOC Error
      1. 7.1.1 Calculating True SOC
      2. 7.1.2 Finding Calculated SOC for Voltage Correlation & Voltage + IR Correction
      3. 7.1.3 Finding Calculated SOC for Coulomb Counting
    2. 7.2 Comparing SOC Error
  11. 8Summary
  12. 9References

7.1.2 Finding Calculated SOC for Voltage Correlation & Voltage + IR Correction

For voltage correlation and voltage + IR correction, an 11-point OCV Table was used. Instead of having the SOC reported in increments of 10%, linear interpolation was used to report a more accurate SOC.

For voltage + IR correction, the internal resistance of the battery was calculated from the first discharge after a relaxation period. After the internal resistance is calculated, any measured voltage during a discharge is normalized using Equation 7.

Equation 7. Normalized Voltage=Measured Voltage+Measured Current*Internal Resistance