Additives can be added to lead acid battery electrodes to increase porosity and improve battery power and energy performance. This paper investigates the influence on electrode performance of different sizes and volume percentages of nonconductive additives to provide a clearer understanding of how they affect battery performance. The nonconductive additives used in the electrodes were hollow glass microspheres (HGMs). The solid volume percentages of various sizes of HGMs were varied from 5 to 60%. The discharge capacity for different volume percentages of the HGMs was measured in plates that were hand pasted to similar thicknesses. The utilization of active materials, which is defined as the ratio of the practical discharge ampere-hours over the stoichiometric capacity of the active materials, was plotted with respect to different solid volume percentages of additives. Experimental results were compared with the theoretical values of conductivity models. The change of utilizations with different solid volume percentages of additives compared favorably with the model predictions.