The new generation of batteries for telecom applications

Under the pressure of deregulation, technology mutations and cost reductions, the telecom networks are evolving rapidly. One characteristic, though, remains crucial: the reliability of communication must be irreproachable. Moreover, communication quality has become a prerequisite to high speed data exchange and a competitive advantage, if not a liability issue, in the rivalry between telecom operators. Faults per 100 main lines, a good indicator of communication quality, decreased of 1% per annum in the past five years in the USA. A remarkable adaptation of telecom networks to new economical and technical rules is happening in the access part of the network, where terminal equipment is being installed closer to the end-user. As a consequence, switching equipment is now being installed more often in compact and remote cabinets, where space is a premium and temperatures can be extreme. The batteries that ensure continuous quality of service during power outages, had, in their turn, to evolve. Remoteness demanded longer maintenance free periods, miniaturization required optimized energy density and uncontrolled environment needed batteries to sustain extreme temperature variations. The purpose of this paper is to compare the performance of various technologies for such remote telecom applications. There exist different types of Ni-Cd technologies: pocket plate, sintered, plastic bonded electrodes. We will primarily focus on the features that are common to all of them: long life, intrinsic reliability, minimum maintenance, mechanical integrity, resistance to electrical abuse, wide operating temperature range, tolerance to temperature variations, safe recycling and, as a result of the previous characteristics, low life cycle cost. This paper will also focus on the performances of the two Ni-Cd technologies that are currently being deployed in the field, across the five continents. Their specific strengths will be fin-ther discussed. Namely low electrolyte consumption and relatively low price, for the pocket plate technology, and high energy density, for the sintered-PBE technology. Ni-Cd is definitely part of the latest generation of telecom batteries. And the next generation is under development, closely following. We will briefly document the potential for lithium ion and nickel-metal hydride batteries for future telecom installations.