Operational characteristics of VRLA batteries configured in parallel strings

It has become more common in telecommunications and other standby power applications to initially install the minimum size battery required and to subsequently install additional battery capacity as service loads and power demands increase at local sites. Many installations even provide planned unused space in the installation in anticipation for additional switches, rectifiers and batteries to accommodate future growth in a local area. Typically battery capacity is increased by paralleling one or more new battery strings with the battery already installed. Theoretically, this approach should be acceptable provided that certain precautions are observed. The purpose of this paper is to provide detailed data on the characteristics of batteries, VRLA designs in particular, operated in parallel configurations.