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ENEA (Italian National Agency for New Technology, Energy and the Environment) has been involved in research and development in the transport sector since the '80s, to reduce energy consumption and environmental impact. Specific testing facilities have been set up in ENEA Casaccia Research Center to perform such activities: a battery test laboratory with test-bench and climatic chambers, a test track for EVs, a fleet of electric passenger cars and vans, a roller bench for medium-size vehicles and a test bed for the complete drivetrains of electric and hybrid vehicles. A test aimed at comparing bench and on-board performance of lead-acid batteries was carried out on a VRLA system, equipping a Panda Larel, using test benches for battery cycling in thermal chambers, a track and the roller stand. For the track testing of a vehicle a special cycle was elaborated, that is similar in some specific properties to the ECE 15, an European cycle proposed for evaluating energy consumption.

The paper deals with the study of an original on-board power system that combines battery, ultracapacitors (UCs) and a Fuel Cell. The project was funded by the Italian Government in the framework of the new Hydrogen Research Project and is conceived as the first step of a project involving ENEA, (Italian National Agency for New Technology, Energy and Environment, and University of Rome “Roma 3”, aimed at developing a Fuel Cell-powered drive train, for a city-car. It foresees the realization of the drive train in a prototype version, powered by a 5 kW DeNora Fuel Cell, and its testing beside the ENEA laboratories in Casaccia. The report highlights the storage system design phase, emphasising the role that ultracapacitors could fulfill in a near future thanks to their peculiar characteristics, and point at an optimisation method, based on the “simplesso method”, for the technical and economic sizing of such a hybrid storage system.

Two testing campaigns were performed in Turin by CRF (the Fiat Research Center), and in Rome by ENEA (the Italian National Agency for New Technologies, Energy and the Environment) and the University "ROMA TRE". The work demonstrates the feature of a FC emulator to characterize fuel-cell-propelled drivetrains without employing an expensive PEM fuel cell and it points out how the vehicle fuel consumption, on a specific mission, depends on two fundamental parameters, the accordance of the FC nominal power with the requested power of the mission and the battery State-of-Charge. In the ENEA Research Center "Casaccia", near Rome, the behaviors of PEM Fuel Cells of different sizes (7, 15, 22 kW) were simulated by replacing them with a controlled AC/DC converter, this fuel cell emulator powering a full-scale hybrid drive train.

When the first hybrid vehicles were commercialized in the early '90, traction lead-acid batteries were used as on board storage system, and their limits in this application were soon complained from users and recognized by manufacturers. Therefore the battery industry has developed specific high-power lead-acid batteries, which constitute an industrialized and economic alternative to the alkaline batteries (Ni-Cd, Ni-MeH). Under the direction and funding support of the Commission of the European Community, the R&D Organization EUCAR (European Council for Automotive Research, a collaborative partnership of most European car manufacturers), has been conducting an autonomous characterization activity of these high-power systems using agreed test procedures, through bench tests carried out by different independent laboratories throughout Europe.