Environmental issues in remote telecommunications sites: hydrogen evolution of VRLA batteries in cellular installations

Modern telecommunications deployment increasingly involves the use of remote sites. Equipment is housed in enclosures that range in size and scope from large concrete buildings containing entire switches to small cabinets containing a few lines of transmission equipment. In most cases, reserve energy during AC power failures is supplied from lead acid batteries collocated with the electronics within the enclosure. The fact that all lead acid batteries generate hydrogen continuously during their operation is an important design parameter for both the enclosure, and the equipment which the batteries are designed to support. While much published material has dealt with VRLA battery operational issues such as hydrogen evolution and thermal runaway from a design and engineering viewpoint, this investigation has attempted to represent a users perspective. In determining the capabilities and limitations of both the batteries and their end users the paper attempts to present some real world principles to aid successful applications. While predominantly focussing on wireless, such principles could also apply to other outside plant type applications