An apparatus for wireless transmission of power from a DC voltage source to a DC voltage load, includes: one primary coil coupled with one secondary coil, the primary coil and the secondary coil each equipped with at least one capacitor, so that the primary coil resonates at a frequency that at least equal the secondary coil resonant frequency; the resonant coils are mutually moveable; a converter that converts the DC voltage at a primary side to an AC voltage of controllable magnitude and frequency; at least one rectifier at the secondary side converts the AC voltage at the terminals of the secondary coil to a DC voltage at the load on the secondary side; and a control system that regulates the power flow by changing the magnitude and frequency of the AC voltage at the terminals of the primary resonant coil.