A new approach to intermittent charging of valve-regulated lead-acid batteries in standby applications

For many years, intensive research has been undertaken to increase the life of valve-regulated lead-acid (VRLA) batteries. Overcharging results in excessive temperature in the battery, which degrades the chemical composition of the electrolyte. When the battery reaches the end-of-charge state, the energy being supplied to the battery is no longer consumed in the charge reaction and this additional energy is dissipated as heat within the battery. At this point, the oxygen cycle accelerates, which leads to temperature rise inside the battery. State-of-the-art control technology is required to control the charging of the battery and prevent the battery going into thermal runaway. This paper discusses the charging strategies for VRLA batteries in standby applications. Intermittent charging decreases the continuous overcharge which arises in the case of float charging. But the charging regime to be used in an intermittent charging is a great dilemma to ensure the full recharge of the battery. This paper describes a new efficient method of charging batteries employing an intermittent charging technique called ´interrupted charge control´. Laboratory tests and results are presented.