This study investigates the influence of the organic expander component (Vanisperse A) and of BaSO4 on the performance of negative lead-acid battery plates on high-rate partial-state-of-charge (HRPSoC) cycling. Batteries operating in the HRPSoC mode should be classified as a separate type of lead-acid batteries. Hence, the additives to the negative plates should differ from the conventional expander composition. It has been established that lignosulfonates are adsorbed onto the lead surface and thus impede the charge processes, which results in impaired reversibility of the charge-discharge processes and hence shorter cycle life on HRPSoC operation, limited by sulfation of the negative plates. BaSO4 exerts the opposite effect: it improves the reversibility of the processes in the HRPSoC mode and hence prolongs the cycle life of the cells. The most pronounced effect of BaSO4 has been registered when it is added in concentration of 1.0 wt.% versus the leady oxide (LO) used for paste preparation. It has also been established that BaSO4 lowers the overpotential of PbSO4 nucleation. The results of the present investigation indicate that BaSO4 affects also the crystallization process of Pb during cell charging. Thus, BaSO4 eventually improves the performance characteristics of lead-acid cells on HRPSoC cycling. (C) 2009 Elsevier B.V. All rights reserved.