Charge equalizing and lifetime increasing with a new charging method for VRLA batteries

Abstract

A new charging method for valve-regulated lead-acid (VRLA) batteries is presented which limits the maximum of all block voltages in a battery string. A commercially available VRLA battery was equipped with cell-pressure and cell-voltage sensors. The new method was applied to the battery in comparison to conventional IU- and IUIa-charging methods. Voltage and pressure measurements during these experiments show clearly that the conventional charging methods lead to excessive overcharge of single cells correlated with irreversible water losses. These problems are efficiently avoided by the new charging method. Capacity data from cycling operation prove as well that the new charging method guarantees charge-equalizing between the inhomogeneous cells while avoiding additional hardware.