A mobile refrigerated system formed as a trailer, a truck, or an intermodal container comprising a refrigerated cargo space wherein perishable cargo is stowed for transport, the mobile refrigerated system comprising: a refrigeration unit having a compressor and a plurality of refrigeration unit electric loads (42, 46, 48) and functioning, under the control of a controller, to establish and regulate a desired product storage temperature within the refrigerated cargo space and to maintain the product storage temperature within a specified temperature range; a power supply system including an engine coupled to the compressor for direct drive powering the compressor, a generator arranged to be driven by the engine for generating electric power, and a power distribution system arranged to receive electric power generated by the generator; and a low voltage battery pack characterized in that the refrigeration unit further comprises a condenser fan and an evaporator fan; the power distribution system further comprises an alternator arranged to be belt driven by the engine for generating electric power; the power distribution system is further arranged to receive electric power generated by the alternator as a first source of direct current power; the power distribution system is configured to selectively distribute electric power to the plurality of refrigeration unit electric loads (42, 46, 48); wherein the power supply system further comprises a high voltage battery pack for storing electric power and providing a second source of direct current power; and wherein the plurality of refrigeration unit loads includes at least one high voltage direct current fan motor (42, 46) selectively powered by at least one of direct current generated by the alternator, direct current from the high voltage battery pack, and direct current derived from converting alternating current generated by the generator. a refrigeration unit having a compressor and a plurality of refrigeration unit electric loads (42, 46, 48) and functioning, under the control of a controller, to establish and regulate a desired product storage temperature within the refrigerated cargo space and to maintain the product storage temperature within a specified temperature range; a power supply system including an engine coupled to the compressor for direct drive powering the compressor, a generator arranged to be driven by the engine for generating electric power, and a power distribution system arranged to receive electric power generated by the generator; and a low voltage battery pack characterized in that the refrigeration unit further comprises a condenser fan and an evaporator fan; the power distribution system further comprises an alternator arranged to be belt driven by the engine for generating electric power; the power distribution system is further arranged to receive electric power generated by the alternator as a first source of direct current power; the power distribution system is configured to selectively distribute electric power to the plurality of refrigeration unit electric loads (42, 46, 48); wherein the power supply system further comprises a high voltage battery pack for storing electric power and providing a second source of direct current power; and wherein the plurality of refrigeration unit loads includes at least one high voltage direct current fan motor (42, 46) selectively powered by at least one of direct current generated by the alternator, direct current from the high voltage battery pack, and direct current derived from converting alternating current generated by the generator.