The analysis based on the second law of thermodynamics of a lightweight vapor compression refrigeration system is presented. A small-scale linear compressor was applied in a DC-powered portable cooler for vehicles and for the medical field, using finned-tube heat exchangers and R600-a (Isobutane) as the working fluid. The cooler was tested in an environmental chamber (with controlled temperature and humidity) under three different ambient temperatures (21, 25 and 32 °C) in order to measure key parameters of the system, such as cooling capacity, power consumption and internal air temperature. For the comparison of thermodynamic irreversibilities, a conventional vapor compression refrigerating system was also tested under the same ambient conditions. Results indicated that the system with the proposed lightweight system kept the lowest internal air temperature with higher coefficients of performance, showing how a lightweight cooling unit can enlarge the use of refrigerating systems due to its attributes.