An apparatus for identifying and reducing an undesired condition of instability in a motor during power generation, the apparatus, comprising: a DC brushless motor, comprising windings and having four quadrants of operation; a switch bridge comprising a plurality of switching units (312, 314, 316, 318, 320, 322) configured to couple a power source to the windings and arranged to form parallel half H-bridges; a motor controller configured to control the plurality of switching units; an undesired condition identifier configured to identify an undesired condition in the apparatus when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source; and an undesired condition reducer configured to reduce the undesired condition in response to identifying the undesired condition in the apparatus by the undesired condition identifier, characterised in that: in being configured to identify the undesired condition in the apparatus when the DC brushless motor is providing the power to the power source, the undesired condition identifier is configured to identify the undesired condition in the apparatus when a voltage across the windings is greater than a first voltage threshold, wherein the first voltage threshold is defined with respect to an output voltage of the power source; and in being configured to reduce the undesired condition in response to identifying the undesired condition in the apparatus, the undesired condition reducer is configured to direct a current in the windings to ground via a variable resistor in response to identifying the undesired condition in the apparatus and configured to select a resistance of the variable resistor in response to a level of the current in the windings; and wherein the variable resistor comprises a plurality of resistors in parallel; and the undesired condition reducer is further configured to select a number of resistors in the plurality of resistors through which the current in the windings is directed to ground based on temperatures of the plurality of resistors. a DC brushless motor, comprising windings and having four quadrants of operation; a switch bridge comprising a plurality of switching units (312, 314, 316, 318, 320, 322) configured to couple a power source to the windings and arranged to form parallel half H-bridges; a motor controller configured to control the plurality of switching units; an undesired condition identifier configured to identify an undesired condition in the apparatus when the motor is providing power to the power source, wherein the undesired condition is defined with respect to a characteristic of the power source; and an undesired condition reducer configured to reduce the undesired condition in response to identifying the undesired condition in the apparatus by the undesired condition identifier, characterised in that: in being configured to identify the undesired condition in the apparatus when the DC brushless motor is providing the power to the power source, the undesired condition identifier is configured to identify the undesired condition in the apparatus when a voltage across the windings is greater than a first voltage threshold, wherein the first voltage threshold is defined with respect to an output voltage of the power source; and in being configured to reduce the undesired condition in response to identifying the undesired condition in the apparatus, the undesired condition reducer is configured to direct a current in the windings to ground via a variable resistor in response to identifying the undesired condition in the apparatus and configured to select a resistance of the variable resistor in response to a level of the current in the windings; and wherein the variable resistor comprises a plurality of resistors in parallel; and the undesired condition reducer is further configured to select a number of resistors in the plurality of resistors through which the current in the windings is directed to ground based on temperatures of the plurality of resistors. in being configured to identify the undesired condition in the apparatus when the DC brushless motor is providing the power to the power source, the undesired condition identifier is configured to identify the undesired condition in the apparatus when a voltage across the windings is greater than a first voltage threshold, wherein the first voltage threshold is defined with respect to an output voltage of the power source; and in being configured to reduce the undesired condition in response to identifying the undesired condition in the apparatus, the undesired condition reducer is configured to direct a current in the windings to ground via a variable resistor in response to identifying the undesired condition in the apparatus and configured to select a resistance of the variable resistor in response to a level of the current in the windings; and wherein the variable resistor comprises a plurality of resistors in parallel; and the undesired condition reducer is further configured to select a number of resistors in the plurality of resistors through which the current in the windings is directed to ground based on temperatures of the plurality of resistors.