Methods for state-of-charge determination and their applications

State-of-charge (SOC) determination becomes an increasingly important issue in all the applications: that include a battery. Former operation strategi es made use of voltage limits only to protect the buttery against deep disc harge and overcharge. Currently, battery operation is changing to what coul d rather be called battery management than simply protection. For this impr oved battery control, the battery SOC is a key factor. Much research work has been done in recent years to improve SOC determinati on. Operational conditions differ for batteries in, for example, photovolta ic applications, (hybrid)-electric vehicles or telecommunications. Hence, a given method fur SOC calculation will be more suitable for a certain appli cation than for another. The authors introduce commonly used methods for SO C determination and establish a relationship between the advantages of the different methods and the most common applications. Al; a main illustration , the analysis of Kalman filter technique for lead-acid battery SOC determi nation are presented and some results for other calculation methods as well . (C) 2001 Elsevier Science B.V. All rights reserved.