New designs of valve-regulated lead-acid batteries for rack mounted telecommunications applications

A new type of monobloc battery was launched onto the telecommunications market in 1993 for 24" deep, 23" telecomms racks as the first of a series of second generation products designed from the authors' experience and user experience of earlier types originally launched in 1982. This paper describes the advantages compared with more conventional products. These include a long narrow footprint for cabinet applications and front terminals for ease of connection and voltage monitoring. The lid is bonded to the box with a specially developed epoxy adhesive which is also used to provide intercell seals and encapsulation of the group bars; intercell welds are unnecessary. This gives advantages of improved energy density and elimination of negative group bar corrosion as a failure mode. The long thin style of battery case, together with outside facing plates, give improved heat transfer which reduces the chance of thermal runaway. Thermal imaging data from this type of battery and more conventional shaped blocs will be used to illustrate this point. The battery element was designed to give a high capacity and a long life. Bell NWT 000766 test results are presented to confirm a 12 year life at 25/spl deg/C. This design philosophy has now been extended into 19" rack systems with 18" deep cabinets through the VJ series of products.