Lead acid battery separators, warp resistant separators, batteries, systems, and related methods

An electrode and separator assembly comprising:

• a positive electrode plate defining a first surface area, the positive electrode plate comprising a grid and active material;
• wherein said grid comprises a first grid edge and a second grid edge, and wherein said grid has a grid thickness less than approximately 1.0 mm;
• a porous membrane disposed adjacent to said electrode plate, said porous membrane comprising a first membrane surface having a first side lane adjacent to a first membrane edge, a second side lane adjacent to a second membrane edge, and a central portion disposed between said first side lane and said second side lane;
• a plurality of primary ribs extending from or into said first membrane surface within said central portion, said primary ribs comprising forty-three toothed ribs arranged in rows, each row offset at least partially from adjacent rows, the primary ribs spaced at a Pitchtooth of from 3.0 to 6.0 mm, the primary ribs having an average tip length, TipLTooth from 50 microns to less than 1.0 mm, an average tooth base length BaseLTooth from greater than 50 μm to 1.0 mm, an average height, HeightPosRib from 50 μm to 1.0 mm, and an average height to base width ratio from 0.1:1.0 to 500:1.0, and a first array of secondary ribs disposed within said first side lane and a second array of secondary ribs disposed within said second side lane;
• and
• wherein the primary ribs are the only ribs within said central portion and all of the primary ribs are longitudinally disposed in a machine direction of the porous membrane, and further wherein the first array of secondary ribs are the only ribs within said first side lane, the second array of secondary ribs are the only ribs within said second side lane, and all of the first array of secondary ribs and all of the second array of secondary ribs are laterally disposed in a cross-machine direction of the porous membrane, and further wherein the primary ribs contact 3.8% of the first surface area of the positive electrode plate.