Future vehicle applications require the development of reliable and long life batteries operating under high-rate partial-state-of-charge (HRPSoC) working conditions. This paper updates work carried out to develop spiral wound valve-regulated lead-acid (VRLA) batteries for vehicles with different hybridisation degrees, ranging from stop-start to mild hybrid applications. Former work on design optimisation and active material formulations has been implemented in two spiral wound VRLA batteries, rated 12 V 50 Ah and 6 V 24 Ah, and these two products are currently being tested both in benches and in vehicles with different hybridisation degrees within a demonstration project funded by the Advanced Lead Acid Battery Consortium and in collaboration with several European vehicle and electrical component manufacturers. (c) 2007 Elsevier B.V. All rights reserved.