Experimental research regarding the autonomy of electric cars in real driving conditions

Abstract

Currently, almost all car manufacturers have in the production scheme at least one vehicle model with a hybrid or electric energy source. This fact is generated by the high interest in the market related to the subsidies offered to the purchase by the states but also by the high performance in terms of pollution, noise, and economy, which they can achieve. The only performance indicator which for the moment is not at a satisfactory level is represented by autonomy. At this point, the electric cars have an autonomy between 250 and 800 km driven after a single charge of the traction battery. It should be mentioned though that, the autonomy of electric vehicles declared by European manufacturers is obtained in laboratory conditions, these being carried out in accordance with the provisions of the European Union regulations. Obviously, there are significant differences between the electric autonomy obtained in laboratory conditions and the autonomy obtained in real driving conditions. These differences are related to the ideal test conditions achieved at the laboratory level and which cannot be fully found in real driving conditions. Starting from these premises, in a first part of the paper, are presented the theoretical arguments regarding the determination of autonomy in real driving conditions with a driving profile specific to the RDE testing and are described the technical details of the electric vehicle under investigation. In the second part of the paper, are presented the results of the experimental research for the three driving zones specific to the RDE testing: driving in the urban zone, driving in the rural zone, and driving on the motorway. The downward evolution of the state of charge of the traction battery for each driving zone is shown graphically. Following the processing, analysis and interpretation of the data acquired from the car electronic control units, are formulated conclusions regarding the causes that influence the electric autonomy.