A cooling system for a drivetrain of an electric vehicle includes a coolant circuit directing a flow of coolant through a first inverter and a second inverter of the drivetrain, and an adjustable flow valve positioned along the coolant circuit to selectably alter proportions of the flow of coolant directed through each of the first inverter and the second inverter. A method of operating a cooling system for a first inverter and a second inverter of a vehicle drivetrain includes commanding a speed and torque of each of the first and second inverter, and estimating losses and temperature of each of the first inverter and the second inverter as a result of the commanded speed and torque. A valve position of an adjustable flow valve operably connected to the first inverter and the second inverter is selected, and a change of the valve position is commanded.