The new automotive architectures will require high-voltage, high-power batteries that are completely different from existing 12V flooded lead–acid products. Battery requirements for these applications are reviewed first from the standpoint of the vehicle, and then from an electrochemical/thermal performance perspective. Design and performance characteristics are then critically evaluated for the three major candidates for the new 36/42V systems, namely: valve-regulated lead–acid (VRLA), nickel–metal-hydride (Ni–MH), and lithium-ion (Li-ion). Design and manufacturing requirements, performance strengths and weaknesses, reliability issues, markets and pricing are then examined for the VRLA battery, which appears to be the leading candidate at this time.