For a large-scale introduction of electric vehicles (EVs) intelligent charging strategies are needed to adjust their energy demand to the production of renewable energy and the current load in the distribution grids. This paper presents an approach that puts the intelligence needed into the EVs, where most of the crucial information arise, thus minimizing the need of communication throughout the grid. The EVs shall be enabled to decide on a charging strategy using an optimization algorithm which creates a charging schedule based on the charging point's and the EV's capabilities, user input, battery degradation and a variable tariff for electricity. This algorithm has been implemented in a control device called the mobile Smart Meter (mSM), which is embedded in the EV, enabling it to handle the necessary communication and to create and monitor an optimized charging strategy. The results of a small-scale field trial shown in this paper delivered the proof of concept of the developed system.