Valve-regulated lead/acid battery designs and charging strategies —are they linked?

Charging algorithms are often closely tailored to or are specified by particular applications, e.g., standby, engine start, traction, etc. When valve-regulated lead/acid (VRLA) batteries are put into these applications, the battery must fit the charging program, regardless of its design. Design principles for VRLA batteries that relate to charging in general are presented and discussed. This is followed by a discussion of the ‘VRLA paradoxʹ—a design requirement for the proper functioning of these batteries, but one that makes charging considerably more difficult than for similar flooded lead/acid batteries. Thermal effects as they relate to battery design and charging are explored, along with the impact of the conditions of the applications. Charging strategies that are best suited to VRLA batteries are examined and recommendations are put forward for both float and cyclic duties; in both cases these recommended approaches are considerably more aggressive than those currently in popular usage. In cyclic charging, the critical role of the charge termination method is explored.