The "art" of designing flooded stationary cells for the central office

The central office continues to play an important role in the overall infrastructure of the telecommunications industry. A key requirement of the central office is its need for continuous hours of problem-free operation. The DC battery plant system of the central office, with its distribution and battery, is the backbone of this highly reliable system. The flooded lead-acid battery is a key to the effectiveness of this back-up power system and is extremely reliable when properly designed and implemented. The state of the art design of flooded lead-acid cells for the central office, did not develop over night, nor was it developed solely by one cell manufacturer. Also, cell designs developed and evaluated in the laboratory, did not necessarily prove out in the central office. For example, the past has seen the insidious nature of corrosion result in several unanticipated failure mechanisms in the field. Fortunately, these not so positive experiences in the field, were able to be utilized to further improve cell reliability and therefore optimize cell life for this demanding application. It is the intention of this paper to address the key design features of large flooded lead-acid cells for the central office. The important design aspects of grids, plates, separators, containers (jars), posts/post seals, and how they impact the lives and reliability of cells are discussed. Examples are used to demonstrate proper component design and will be of interest to those involved in the design or the purchasing of battery systems.