Coulomb Counting
Definition
Method of estimating state-of-charge by integrating current flow over time (1 coulomb = 1 ampere-second). Primary technique used by BMS for SOC estimation.
Why It Matters
- More accurate than voltage-based SOC estimation under load
- Provides real-time SOC updates during charge/discharge
- Requires accurate current sensor and integration over time
- Must be periodically recalibrated to prevent drift
Common Pitfalls
- Current sensor offset errors accumulate over time
- Not compensating for self-discharge
- Ignoring coulombic efficiency (charge/discharge ratio)
- Not recalibrating SOC with voltage-based endpoints