For many decades, the lead-acid battery has been the most widely used energy-storage device for medium- and large-scale applications (approximately 100Wh and above). In recent years, the traditional, flooded design of the battery has begun to be replaced by an alternative design. This version - the valve-regulated lead-acid (VRLA) battery - requires no replenishment of the water content of the electrolyte solution, does not spill liquids, and can be used in any desired orientation. Since the VRLA battery operates in a somewhat different manner from its flooded counterpart, considerable...