New developments in batteries for fiber-in-the-loop applications

The rapid deployment of power in uncontrolled environments and unusual installation configurations for fiber-in-the-loop applications is posing new challenges to battery and battery system designers. Battery string voltages and discharge rates are also higher than in traditional telecommunications applications. Battery materials and designs must be chosen to withstand extreme temperatures, and manufacturing processes must provide greater product uniformity to enhance battery life. At the same time, the system must be designed to control the charging currents even at extreme temperatures under fault conditions to avoid catastrophic failures such as shorting and thermal runaway. The authors describe how a slope/plateau/step approach to temperature compensation and a current limiter are two ways to control the charging currents and extend battery life. With careful system design, valve-regulated lead-acid batteries are the best power source in the near term.