High Power Lithium-ion battery: First Field Trial Results of an advanced Backup System for Advanced Cellular Networks

Based on 14 years experience with batteries in both MSC (mobile switching centre) and BTS (base transceiver stations), Vodafone D2 Germany is looking for alternatives to VRLA batteries especially in outdoor cabinets, to answer their changing requirements in terms of life and reliability, operational needs, impact on OpEx and CapEx, and environmental compatibility. The major challenges inside outdoor cabinets are high temperatures, leading to short battery life time, and limited space available for equipment. Li-ion batteries seem to be an alternative, and Saft has developed a rack-mount battery system with an improved lithium-ion cell, which brings it to the levels of compactness, scalability, reliability and life expected for today's cellular base stations. In 2004, at the final stage of product development, Vodafone D2 tested one prototype in a live base stations to assess their compatibility with existing rectifiers and loads. This paper explains the evolving base station backup requirements from Vodafone. The technical developments on Li-ion cells (high power performance, safety, life time) will be briefly exposed, and system integration and the resulting characteristics of a telecom rack-mount battery will be shown. Finally, protocols of tests conduced with the live Vodafone base station will be presented