How does the BMS calculate and monitor SOC and SOH?
A Battery Management System (BMS) calculates and monitors SOC (State of Charge) and SOH (State of Health) by combining real-time electrical measurements with mathematical models and estimation algorithms.
These two parameters are essential for understanding battery performance, safety, and remaining lifespan in lithium-ion and LiFePO4 battery systems.
What is SOC in a BMS system?
SOC represents the current available energy inside a battery, usually expressed as a percentage. A BMS continuously estimates SOC using voltage, current, and temperature data.
Main SOC calculation methods
- Coulomb counting: measures charge in and out over time
- Voltage-based estimation: uses open circuit voltage correlation
- Model-based estimation: combines electrical battery models
What is SOH in a BMS system?
SOH indicates the overall health of a battery compared to its original rated capacity. It reflects degradation caused by cycle aging, temperature stress, and internal resistance increase.
Main SOH estimation methods
- Capacity fade measurement
- Internal resistance tracking
- Cycle life modeling
How BMS calculates SOC and SOH in real systems
Modern BMS systems combine multiple data sources including voltage, current, and temperature sensors. These inputs are processed using algorithms such as Kalman filtering, coulomb counting, and machine learning models.
SOC and SOH estimation is continuously corrected during charging and discharging cycles to improve accuracy over time.
Why SOC and SOH monitoring is important
- Prevents overcharging and deep discharge
- Improves battery safety and reliability
- Enables predictive maintenance
- Extends battery lifespan in industrial applications