Lead-Acid Battery: Float Behavior of the Lead-Acid Battery System

(Manuscript received April 30,1970) The design of any battery involves many factors, some to be dealt with empirically and some by analysis in light of more fundamental understanding. These factors combine to determine end behavior and, consequently, utility; detailed considerations of them with regard to the Bell System lead-acid battery appear elsewhere in this series of papers. Here, we consider the more general topic of float operation of lead-acid batteries with as much concern for fundamentals as seems appropriate, using the behavior of typical rectangular lead-calcium grid cells to illustrate the treatment. Although stationary lead-acid batteries, used for load-averaging and reserve power in the Bell System, are commonly maintained by connection to a constant voltage bus, a procedure known as floating, there is surprisingly little published information about the details of this process and the effects of cell and electrode characteristics on its operation. The standard text on storage batteries1 makes only brief mention of float operation and, in fact, provides very little information even about the overcharge behavior of cells. The purpose of float is, of course, to maintain a battery in a full state 1321