1950-2001: more than one-half century of learning how to live with each new generation of telecommunication standby batteries

This paper traces the Bell System\´s 50 year adventure with the problems and solutions resulting from each new standby battery technology introduced into widespread system use. It describes the change in 1950, from almost 50 years of lead antimony (PbSb) usage to lead calcium (PbCa) technology. The next 12 years resulted in traumatic voltage irregularities, capacity failures, jar cracking and breakage, serious seal leakage and actual fires and explosions. These problems stimulated 10-20 years of tests, research and development, leading finally to a well understood, reliable, long life, non-antimonial, flooded cell technology. Then, just as this understanding was being digested, valve-regulated lead acid (VRLA) technology was introduced. The promises and realities of VRLA performance and life are described. The search for a non-invasive technique to characterize the "state of health" of VRLA cells, led to a massive capacity/conductance correlation study. The study involving >24,000 cells has validated the correlation between ohmic techniques and VRLA capacity, as measured directly off float. It also led to the realization that premature capacity failure was common in the two American studies of >40,000 cells and a Swedish study of >35,000 cells. Further research has produced a new "balanced cell" concept, which explains some of the failures and has led to both simple, immediate solutions as well as more complex, elegant solutions to prevent cell imbalance. Alternate solutions include introduction of flooded nickel-cadmium (NiCd) batteries into both existing and new installations and field trials currently underway, utilizing prototype high temperature, lithium-polymer technologies in standby distributed power applications.