Battery separator material

A battery separator which is acid wettable but not water wettable and which comprises a substantially uniform mixture of from about 5 to about 20 percent by weight of the separator of polyolefin fiber, from about 2 to about 15 percent by weight of polyester fiber, from 0 to about 20 percent by weight of glass fiber, from about 40 to about 75 percent by weight of diatomaceous earth and from about 7 to about 20 percent by weight of an acrylate copolymer binder which includes a silane coupling agent attached to the polymeric backbone, said separator being characterized by a total pore volume of about 70 percent or higher with an average pore size between about 5 to about 30 microns and an ohmic resistance of about 0.015 ohms per inch.sup.2 or less.