Failure mechanism of valve-regulated lead acid battery for deep cycle application

The failure mechanism of valve regulated lead acid (VRLA) battery for deep cycle application was studied. The cycle life of the batteries produced in the same batch was tested with various charge regimes, and the failed batteries were disassembled and analyzed by X ray diffraction(XRD). The results show that when the battery is charged at low current and constant voltage, its failure mode is the sulphation of negative plate and the softening of positive plate; when the battery is charged with optimized regime, its failure mode is the softening of positive active material while the corrosion grade of grid is low. The methods for extending cycle life of VRLA for deep cycle application is also presented according to the discussion of failure mechanism.