The electrochemical storage of energy in automobiles faces the possibility of a major change, in that the electrical systems planned for vehicles are expected to be far more extensive than hitherto. These advanced electrical systems will require the electrical energy-storage element (one or more batteries) to operate at a partial-state-of-charge for most of its life and at unprecedented high rates (so-called 'HRPSoC duty'). The remarkable advances achieved with valve-regulated lead-acid (VRLA) battery technology for electric vehicles (EVs) during the past 8-10 years will be of only passing value in overcoming the challenges posed by HRPSoC duty. This is because the battery failure modes seen in HRPSoC operation are quite different from those faced in EV (deep-cycle) use. The replacement of the 12 V automotive battery will not take place rapidly. If the applications that take its place are to be satisfied by a lead-acid product (probably VRLA), rather than by a battery of a different chemistry, a programme of development as successful as that mounted for deep-cycle duty will be required. (C) 2004 Elsevier B.V. All rights reserved.