Through recent technology advances in the eld of wireless energy transmission, Wireless Rechargeable Sensor Networks (WRSN) have emerged. In this new paradigm for WSNs a mobile entity called Mobile Charger (MC) traverses the network and replenishes the dissipated energy of sensors. In this work we rst provide a formal denition of the charging dispatch decision problem and prove its computational hardness. We then investigate how to optimize the tradeo s of several critical aspects of the charging process such as a) the trajectory of the charger, b) the dierent charging policies and c) the impact of the ratio of the energy the MC may deliver to the sensors over the total available energy in the network. In the light of these optimizations, we then study the impact of the charging process to the network lifetime for three characteristic underlying routing protocols; a greedy protocol, a clustering protocol and an energy balancing protocol. Finally, we propose a Mobile Charging Protocol that locally adapts the circular trajectory of the MC to the energy dissipation rate of each sub-region of the network. We compare this protocol against several MC trajectories for all three routing families by a detailed experimental evaluation. The derived ndings demonstrate signicant performance gains, both with respect to the no charger case as well as the dierent charging alternatives; in particular, the performance improvements include the network lifetime, as well as connectivity, coverage and energy balance properties.