The goal of this paper is to demonstrate how separator pro- file selection can be used to optimize battery performance and manufacturing efficiencies. Descriptions will be given for novel separator profiles, which may bring even greater benefits in the future. All major lead-acid battery applications will be considered including automotive, motive power and power backup systems, most often referred to as stationary. Before considering separator profile design, it will help to define the primary function of the separator, especially the profile, and then to define the terms that will be used throughout this paper. A lead-acid battery separator is basically an acid resistant, flat sheet, porous membrane with ribs protruding from its surface. The separator must be porous for ions to flow between the anode and cathode. To prevent development of the electrical conductance between the positive and negative electrodes stemming from dendritic formation of lead particles, the separator should preferably be micro-porous. In a flooded or a gelled electrolyte lead-acid battery, the separator typically will have protrusions (i.e., ribs) projecting from the planar surface of the substrate, and typically aligned in the lengthwise direction of the plate. The ribs serve to maintain a fixed distance between the electrodes and ensure sufficient acid volume between the electrodes. In a lead-acid battery, the sulfuric acid functions as the electrolyte, the transport mechanism for ion flow between the electrodes. Secondly, the sulfuric acid is a reactant in the reversible charge/discharge reactions, and can be the limiting factor regulating the rate and termination point of the energy storage reactions. Consequently, as changes are made to the rib design, the quantity of acid between the plates will change, and may subsequently alter the charge/discharge reactions