Battery parallelization enables the use of second-life electric vehicle batteries and low-cost battery technology in energy storage systems for smart grid applications. Partial power DC/DC converters can connect batteries in parallel with higher efficiency compared to traditional AC/DC and DC/DC converters thanks to their reduced power requirements. This work presents the design and the implementation of a scaled prototype of a partial power DC/DC converter based on the buck-boost topology. The prototype was characterized achieving efficiencies from 84.1% to 93.2% for different output power levels. The characterization of the implemented DC/DC converter allowed us to develop an accurate model. This model will enable us to gain a deeper understanding of battery parallelization in stationary energy storage applications.