The characteristics evolving from various VRLA battery designs

A review of valve-regulated Pb-acid (VRLA) battery Intelec papers 1982-1994 has identified four main areas of interest: developments; performance; theory; and operations. Development and operations are linked together insofar as operations describes the performance of batteries designed from developed VRLA products. Improvements in battery design and system operation are identified to minimise thermal problems. Changes in the internal construction of VRLAs have been reviewed which either directly or indirectly are designed to stabilise and reduce the level of float currents. Grid alloys with better corrosion resistance at elevated temperatures have been reported and their potential benefit to service life has been noted. The theoretical and performance papers constitute the largest contribution to papers published, and one third of this group have addressed the attributes and deficiencies pertaining to gelled versus AGM systems. A considerable amount of useful data has however been reported on the characteristics of VRLAs and this has been used to develop the concept that VRLAs should be considered in terms of the degree of electrolyte saturation within the cell. Using this concept and relationships between: electrolyte saturation; electrolyte specific gravity; overvoltage; open circuit voltage; and float voltage; simple models have been proposed to identify the scope of the characteristics arising within the various VRLA systems. The preferred model for UK telecommunications power supply is identified and experience in service since 1982 has justified this choice.