Development of valve-regulated lead acid batteries for power storage

The authors developed valve-regulated lead-acid batteries for power storage with long cycle life, designed for accumulating excess power that is cheap during the nighttime and for making peak cuts in daytime power and for leveling the loads. To increase their cycle life, the units were made to conform to a new set of specifications, such as (1) an positive plate composed of a highly corrosion-resistant grid alloy and a high density active material, (2) a negative plate with an additive to increase charge performance, (3) the horizontal installation of the battery, (4) use of a new retainer, and (5) optimal charge conditions. The developed batteries achieve unprecedentedly excellent characteristics, with a cycle life of 3,000 cycles (DOD70%, 10HR, 25 /spl deg/C) and a charge/discharge power efficiency of 85%.