A transportation refrigeration unit including: at least one component powered by an energy storage device composed of a first energy storage pack and a second energy storage pack, wherein the at least one component draws electrical power from the energy storage device at an operating power; a return air temperature sensor to detect a return air temperature; a controller to adjust the operating power in response to the return air temperature, wherein the controller determines a state of charge of the first energy storage pack and a state of charge of the second energy storage pack, wherein the controller selects at least one of the first energy storage pack and the second energy storage pack to power the at least one component in response to the operating power, the state of charge of the first energy storage pack, and the state of charge of the second energy storage pack.