Performance of valve-regulated lead/acid test cells for float operation using modified positive active materials

Three types of valve-regulated lead/acid cells have been made with positive active material prepared from: (i) tribasic lead sulfate; (ii) tetrabasic lead sulfate; (iii) tetrabasic lead sulfate with graphite added. The cells have been subjected to float operation. They undergo premature capacity loss. The circumstances of this effect, the possibility of recovery of the capacity, the role of the graphite, and the impedance spectra of the cells are discussed.