NOVELTY - The battery separator has a negative active material surface to which a carbon or mineral additive is applied. The additive comprises engineered carbon materials for modifying sulfate crystal formation while reducing detrimental consequences of excessive gas evolution into a negative electrode. The additive includes an aqueous coating solution having 0.5 wt. %-10 wt. % of an ionic surfactant, and carbon black in a finely divided powdered form dispersed into the aqueous surfactant solution. The surfactant is sodium dihexylsulfosuccinate.    USE - Battery separator of a lead acid battery (claimed). Can be used for idle stop start (ISS) battery, hybrid electric vehicle (HEV) battery, and enhanced flooded battery (EFB).    ADVANTAGE - Enhances lead acid energy storage performance of the battery, by modifying sulfate crystal formation while reducing detrimental consequences of excessive gas evolution into a negative electrode. Incremental removal of the carbon additives from the negative active material in favor of utilizing the negative surface of the separator as a carbon additive platform removes carbon from the negative active material to allow for additional active material or reduction in manufacturing complexity and cost, provides surface area for sulfate crystal nucleation without the corresponding loss of negative plate porosity especially in partial state of charge (PSoC) operation, and ensures that gas evolution at the plate proceeds normally without excessive nucleation within the plate pores. The carbon additive may most effectively enhance charge acceptance and improve life cycle performance of the battery, and also enhance charge rate and reserve capacity and reduce lead content of the battery. The separator applied with the additive reduces separator electrical resistance, increases cold cranking amperage efficiency, increases open circuit voltage, minimizes entrapped gas, improves capacitance properties, improves use of active material, and reduces energy consumption and negative plate diffusion, as well as improves operation of flooded and valve-regulated lead-acid energy storage devices.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method of enhancing the lead-acid energy storage performance of a lead acid battery.