Nowadays, polyethylene separators are the predominantly used separators in industrial lead-acid traction batteries. A new polyethylene separator called DARAMIC heavy duty, that comprises an additive, was developed as an option for heavy-duty traction applications. This new separator combines the favorable polyethylene separator characteristics with an end-of-charge voltage behavior very similar to rubber separators. In this paper, physico-chemical separator properties and battery test results are presented showing the positive effect of this new separator in terms of antimony poisoning retardation. (c) 2005 Elsevier B.V. All rights reserved.