Industrial lithium ion batteries: from the laboratory to real telecom application

Papers presented at previous Intelec conferences have shown that lithium ion batteries present significant benefits to telecom operators. They offer zero maintenance and will provide long operating life, even under high temperature conditions. More importantly, lithium batteries are very light and compact, and these are two precious characteristics for telecom operators, especially in the context of greater power needs and decreasing allowable battery space and weight (pole-mounted cabinets, right-of-ways...). The main issues that must be addressed in commercializing this technology are safety and compatibility with existing chargers. This paper discusses the packaging of lithium ion cells into modules that allow direct replacement of common VRLA batteries in outside plant applications. The modules incorporate electronic controls that provide for operational safety and plug-and-play functionality with existing telecom rectifiers. The main features of the electronics are discussed, including cell balancing, current limiting, and other protective devices. Saft is also working with a large telecom operator in North America to install a number of demonstration systems in active network nodes. Details are provided for locations, cabinet types, and battery dimensional and capacity requirements. As discussed in the earlier papers, Saft is operating long-term floating tests at temperatures up to 60/spl deg/C. Those tests have been running for well over 2 years, with excellent results. The latest experimental data are provided, along with substantiation of extrapolated life claims.