A unique system may include a power absorber; an electrical machine coupled to the power absorber and operative to supply mechanical power to the power absorber; a drive coupled to the electrical machine and operative to supply electrical power to drive the electrical machine; and a controller communicatively coupled to the drive. The controller may be configured to execute program instructions to selectively vary a control voltage while maintaining a given torque output of the electrical machine, and to determine, based on varying the control voltage, a minimum current required for the electrical machine to maintain the given torque output.