Determination of the piezoelectric element temperature and its utilization for correcting the drive voltage

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, which is corrected for the piezoelectric element's temperature. The piezoelectric element's temperature is determined by loss efficiency.