The balance of end-user requirements which result in multiple design options will ultimately define the configuration of 36-/42-V lead-acid batteries used in future vehicles. Analysis of the driving forces, i.e. high power output, space and weight minimization, and especially cost/benefit considerations, reveal a high probability for a 36-V flooded, prismatic, battery design. The main requirements on the separator will be superior oxidation stability and high puncture strength, i.e. to levels far beyond what are achievable today. (C) 2003 Elsevier Science B.V. All rights reserved.