  Autonomy of devices is a major challenge in many Internet of Things (IoT)
applications, in particular when the nodes are deployed remotely or difficult
to assess places. In this paper we present an approach to provide energy to
these devices by Unmanned Aerial Vehicles (UAVs). Therefore, the two major
challenges, finding and charging the node are presented. We propose a model to
give the energy constrained node an unlimited autonomy by taken the Wireless
Power Transfer (WPT) link and battery capacity into account. Selecting the most
suitable battery technology allows a reduction in battery capacity and waste.
Moreover, an upgrade of existing IoT nodes is feasible with a limited impact on
the design and form factor.
