Assessment of high power HEV lead-acid battery advancements by comparative benchmarking with a European test procedure Mario Conte a,* , Giovanni Pede a , Vincenzo Sglavo a , Diego Macerata b a Italian National Agency for New Technology, Energy and the Environment (ENEA), CR Casaccia Via Anguillarese, Maria di Galeria, 301 00060 Rome, Italy b FIAT Research Centre (CRF), Strada Torino 50 10043 Orbassano, Italy Abstract The technical and practical suitability of lead-acid batteries for applications in vehicles with electrical drivetrains (battery-powered or hybrid electric) has been experimentally investigated in a variety of testing programmes. Under the direction and funding support of the Commission of the European Community, since early 1990s, the R&D Organisation EUCAR, a collaborative partnership of most European car manufacturers, has been conducting battery technological assessment projects, through bench tests carried out by different independent laboratories throughout Europe, using agreed test procedures. In this framework, ENEA acted as independent testing institute and tested, among others, three high power lead-acid batteries of various technologies (flat plate electrodes and spiral wound) for EV and HEV applications. In addition, different battery sizes and operating conditions have been tested at ENEA in a separate collaboration with ALTRA- IRISBUS. This paper intends to trace technological and performance improvements of high power lead-acid battery technology through the analysis of experimental data during parameter and life cycle tests, including the effects of battery sizes, charge/discharge profiles and testing procedures, with special emphasis on the reduction of the internal resistance and the variation of peak power and cycle life. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Lead-acid; Battery; High power; Hybrid electric vehicles; Testing procedures; Technology development 1. Introduction The progress of automotive engineering is requiring new and diversified functions for the onboard energy storage systems. Storage electrochemical batteries, and even super- capacitors, are researched and developed in a variety of chemistries and configurations to better meet the continu- ously changing technical and economical requirements for battery-powered electric vehicles (EVs), hybrid electric vehicles (HEVs), and even conventional internal combustion engine vehicles (ICEVs) with 42 V electrical chain. As a consequence of these changes, the lead-acid battery industry has been producing more specialised products with dedi- cated performance characteristics for the various automotive applications. In particular, in recent years the lead-acid battery technology has been largely modified to improve high power performances and meet specific requirements of HEV applications. In more than 10 years, the R&D Organisation EUCAR of many European car manufacturers (BMW, Fiat, Daimler- Chrysler, Opel, PSA, Renault, Volkswagen, Volvo) has been investigating, under the direction and funding support of the Commission of the European Community (EC), through an experimental and practical approach the commercial and under development energy storage technologies (battery and supercapacitors) for battery-powered (EVs) and hybrid elec- tric vehicles (HEVs). Many projects have been funded until now, with the last one (ASTOR), started on April 2001 and lasting 36 months. One of the fundamental results of those projects has been the definition, in collaboration with many independent European testing institutes, of a set of testing procedures [1,2], which have been applied to experimentally assess and compare energy storage performances and prop- erties in different vehicular applications. The results are of high value and quality for the EUCAR members [3], because they can establish their investment plans and may create competition among component manufacturers, by directing their efforts towards car makers needs. According to the distribution of the work among EUCAR members, FIAT Research Centre (CRF) has always had the Journal of Power Sources 116 (2003) 118–127 * Corresponding author. Tel.: þ39-6-3048-4829; fax: þ39-6-3048-6306. E-mail address: conte@casaccia.enea.it (M. Conte). 0378-7753/03/$ – see front matter # 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0378-7753(02)00715-2