Abstract: A method for state-of-health monitoring of a powertrain component in an electric vehicle system includes: determining an equivalent circuit model of the powertrain component; modeling heat losses in the powertrain component considering both transient and steady-state conditions; modeling heat flow through the powertrain component based on one or more material properties of the powertrain component; determining a temperature of a particular structure within the powertrain component; and determining, using a Rainflow algorithm, a number of temperature cycles until failure of the particular structure based on the temperature of the particular structure.