eSite Power Systems AB recognizes the potential to improve their testing processes for system validation and verification. Presently, eSite utilizes lithium-ion battery packs for their testing, resulting in substantial energy wastage during charge and discharge cycles of the battery packs. To address this the company aims to shift to a real-time emulation method utilizing an accurate model of lithium-ion battery packs. This study presents the development of a real-time battery emulator designed to simulate the behavior of lithium-ion batteries based on the 3RC (Three Resistance-Capacitance) model. The emulator was developed to meet the requirements of eSite Power Systems, incorporating features such as real-time plotting and using the C++ programming language for compatibility with the eSite system. The battery model was validated using the emulator output during a pulse discharge test against synthetic pulse discharge test provided by MATLAB. The emulator's final parameters were validated through simulation and found to accurately represent battery dynamics. The successful implementation of an accurate battery model in a real-time simulation may reduce energy wastage but also advances the eSite Power System AB commitment to environmentally practices.