Thermal management design of battery compartments of outdoor telecommunication cabinets

Telephone operating companies have a long history of powering switching systems with batteries. Instead of large central offices, current trends are towards remote switches, closer to the customer. This poses new problems, since manpower is now required at multiple locations. Further, the ambient temperature within the remote terminals is heavily influenced by the outside environment, described by a -40°C to +65°C temperature range and solar loading, which are telephony industry standards. The life of a battery is directly related to the load applied, proper recharging and, most of all, the ambient temperature of the battery which must be kept at optimum conditions. Batteries for back-up service normally are stored in compartments attached to or inside outdoor cabinets. These compartments are exposed to solar loads, and must be kept at optimum temperatures, 77°F (25°C), as prescribed by the manufacturers. Furthermore, these compartments must allow for the proper venting of fumes that may be given off by the batteries in the course of their operating life. This paper describes the thermal analysis of typical battery compartments (above and below ground). Furthermore, the different approaches open to engineers for the design and development of thermal management systems are presented with some examples. Both passive and active means of thermal management are included in the discussion