The charge equalizer. A new system to extend battery lifetime in PV-systems, UPS and electric vehicles

Investigations of battery banks in PV-systems, UPS and electric vehicles show that the inherent different properties of single cells leads to premature failures of the whole battery. Single cell monitoring is no way to overcome this problem. The new "CHarge EQualizer" (CHEQ) introduced in this paper keeps all cells in the same state of charge at all times by transferring energy between the cells. For different applications specially suited realizations of this fundamental principle will be shown. The main advantages of the CHEQ are the protection against overcharging and deep discharging of individual cells, extension of lifetime, decrease of maintenance costs, and the availability of the full nominal battery capacity.