Flooded lead acid batteries designed for UPS has now evolved to resemble that for telecommunication in that they also utilize retention mats to support the positive active mass. Early designs, developed around the desire to maximize the energy density, did not use such mats. This led to premature battery failure, particularly because the UPS is by design quite interactive with the battery, leading to appreciable cycling. C&D's experience in design and evaluation of life characteristics of different standby battery products is discussed in relation to the evolution of modern UPS battery. The effects of ac ripple, cycling to various depths of discharge, contribution of antimony or calcium grid alloy towards ability to cycle, gas generation and cell maintenance are among the topics covered. Tests show that the high rate cycling, typical of UPS usage, stresses the plate surface and accelerates failure due to shedding irrespective of the grid alloy. Supporting the positive active material with a retention system is critical for extended battery life.
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