Method and apparatus for charging a piezoelectric element

The invention describes a method and an apparatus for charging a piezoelectric element, for example, used as an actuator in a fuel injection system of an internal combustion engine. The method and apparatus are characterized in that the piezoelectric element is activated by an activation voltage having a value set as a function of a capacitance of the piezoelectric element, the capacitance being determined based upon a measured activation energy for charging the piezoelectric element and based upon, for example, a correction value for injected fuel volume.