The ultimate objective of this project is to demonstrate that a valve-regulated lead-acid battery of dual-tab design can be successfully substituted for the nickel-metal hydride battery pack in a Honda Insight hybrid electric vehicle. While the realization of the construction of the battery modules, the battery management system and the associated software has been more complex and time-consuming than was originally envisaged, the battery has now been fitted into the vehicle. With the initial system integration work now complete, the project plan is to test the vehicle with its lead-acid battery for up to 50,000 miles over a combination of the high speed, hill and urban circuits at the Millbrook Proving Grounds in the UK, as well as in general road driving. Prior to this, the developmental battery will have new cells fitted because of the uncertain cycling history of the original cells during the prolonged development period. (c) 2004 Elsevier B.V. All rights reserved.