Plug-to-wheel energy balance - Results of a two years experience behind the wheel of electric vehicles

In this paper, a plug-to-wheel energy balance is made of battery electrical vehicles. The study is based on real data from a two years continuous monitoring of five Peugeot iOn cars, that was performed in Belgium since June 2011, with the financing and support of Electrabel. Different driving styles, trip profiles, type and intensity of use were observed, leading to different energy patterns. The AC/DC vehicle (slow) charge efficiency and brake energy recovering are considered, as well as battery efficiency and auxiliary consumption. In particular, seasonal impacts on battery efficiency and auxiliary consumption are taken into account. This gives valuable information that cannot be obtained from theoretical, e.g. NEDC measuring conditions. A broad range of values is obtained for the average plug-to-wheel efficiency. The resulting well-to-wheel efficiency is slightly better than the one of classical cars, but can still be significantly improved. The consumption of the auxiliaries is of particular importance in the total balance. Because of a higher impact of the auxiliary consumption, cars with a higher urban use show a globally lower plug-to-wheel efficiency. This is an important result when considering the urban trips as the primary segment for EV, and should encourage the EV manufacturers to focus on the reduction of auxiliary consumption. On a yearly basis, regenerative braking can be sufficient to compensate, and even over-compensate the plug-to-battery losses. The average battery losses are limited, even if they can be significant during the cold days.