Abstract: There is provided a wind turbine pitch drive unit comprising an electrical energy storage, a resistor, and a cooling fan arranged to provide an air flow over the resistor. The pitch drive unit is configured to discharge the electrical energy storage by: connecting the electrical energy storage to the resistor such that a current from the electrical energy storage flows through the resistor; disconnecting the electrical energy storage from the resistor when a voltage across the electrical energy storage reaches a first pre-determined threshold; and once the voltage has reached the first pre-determined threshold, powering the cooling fan with the electrical energy storage until the voltage reaches a second pre-defined voltage, thereby cooling the resistor.