A large size 80 V bipolar lead acid battery was constructed and tested successfully with a drive cycle especially developed for a HEV. The bipolar battery was made using the bipolar plate developed at TNO and an optimised paste developed by Centurion. An empirical model was derived for calculating the Ragone plot from the results from a small size 12 V bipolar lead-acid battery. This resulted in a specific power of 340 W/kg for the 80 V module. The Ragone plot was calculated at t = 5 and t = 10 s after the discharge started for current densities varying from 0.02 to 1.2 A/cm(2). A further development of the bipolar lead-acid battery will result in a specific power of 500 W/kg or more. From the economic analysis we estimate that the price of this high power battery will be in the order of 500 US$/kWh. This price is substantially lower than for comparable high power battery systems. This makes it an acceptable candidate future for HEV. (C) 2001 Elsevier Science B.V. All rights reserved.