The last eight years have seen a major shift in vehicle design toward smaller, more fuel efficient automobiles and light trucks. Because of their inherent fuel economy advantage, Diesel engines have made a significant entry into the market. Their extremely high cold cranking power requirements have in turn created a challenge to battery design engineers.Detailed attention to two areas of battery design has provided the power output improvements necessary for reliable starting performance. Battery electrical performance goals have been achieved through evolutionary changes in design parameters which were quantified by application of computer modeling techniques to designing for maximum power. Data has been generated for a specific battery group size which contrasts conventional and diesel battery performance characteristics.