Simple Calibration Circuit Maximizes Accuracy in Li-Ion Battery Management Systems

In Li-Ion battery systems it is important to match the charge condition of each cell to maximize pack performance and longevity. Cell life improves by avoiding both deep discharge and overcharge, so typical systems strive for operation between 20% and 80% states of charge (SOC). Detection and correction of charge imbalances assures that all cells track within the desired SOC window, preventing premature aging of some cells that could compromise the entire pack capacity. Highly accurate measurements are required to determine SOC with Li-Ion cells due to their exceptionally flat discharge characteristics, particularly with the lower voltage chemistries