Chapter 7 - Stationary applications. I. lead-acid batteries for telecommunications and UPS

Abstract

This chapter presents the types of lead/acid batteries for stationary applications, focusing on valve-regulated lead/acid (VRLA) designs. Batteries with capacities up to 200 Ah usually have flat positive plates; for higher capacities, tubular designs are also used. Lead/acid batteries were first used in stationary, stand-by applications more than 130 years ago. For a long period, there were only flooded batteries; however, nowadays, UPS and telecommunications applications use valve-regulated designs. Large, utility-scale applications, such as load leveling, continue to use flooded batteries, but increasingly, valve-regulated batteries are chosen even for these applications. During stand-by service, the battery should be maintained in a completely charged state by applying a float voltage that is slightly higher than the battery open-circuit voltage and that provides the energy for all the side reactions in the battery. These reactions are, in general, grid corrosion and oxygen evolution at the positive plate and hydrogen evolution and, in case of valve-regulated batteries, recombination of oxygen at the negative plate. The choice of the optimum float voltage at different temperatures is an important factor in maintaining valve-regulated batteries in a healthy state. The chapter also discusses two ways for improving the power performance of lead/acid batteries—namely, reduction of the electrical resistance of the current collector parts, optimization of the active materials, and the cell design. For applications where cost and long service life have lower priority, an extremely high power density has been achieved. The measures that improve power give lower cycling performance and vice versa. Recent developments have shown that very high power can be combined with excellent cycle life through the adoption of novel cell design.