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

3 Voltage + IR Correction

Voltage + IR Correction expands on voltage correlation by taking into account the IR drop that occurs when a load is applied to a battery. The amount of IR drop depends on the internal impedance of the battery, the amount of load current, and the temperature of the battery.

GUID-C92E045F-91DB-44BC-80FB-395063BA158B-low.png Figure 3-1 Voltage + IR Drop Graph

The downsides with Voltage + IR Correction is that this can have a greater error when gauging aged cells and or when the battery is exposed to low temperature, since the internal impedance increases. However, Voltage + IR Correction improves on some of the drawbacks to voltage correlation. SOC is able to be adjusted for discharge rate and temperature towards the end of discharge.