Simultaneous charge/discharge of battery for transportation refrigeration usage

A transportation refrigeration unit comprising:

• at least one component of the transportation refrigeration unit 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 of the transportation refrigeration unit draws electrical power from the energy storage device at an operating power;
• a return air temperature sensor to detect return air temperature of return air returning to the transportation refrigeration unit;
• 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 the first energy storage pack or the second energy storage pack to power the at least one component of the transportation refrigeration unit 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;
• wherein only one of the first energy storage pack and the second energy storage pack can power the at least one component of the transportation refrigeration unit at a single time;
• wherein the controller selects the first energy storage pack to be charged by an electrical power source when the first energy storage pack is not powering the at least one component of the transportation refrigeration unit;
• wherein the controller selects the second energy storage pack to be charged by an electrical power source when the second energy storage pack is not powering the at least one component of the transportation refrigeration unit;
• wherein the first energy storage pack includes a battery system and the second energy storage pack includes a battery system.