The current breakthroughs in energy storage technologies, power electronic converters, motor drives, and appropriate control theories have the globe paying special attention to electric vehicles, or EVs. One of the home transportation technologies that will soon be greatly favored over traditional automobiles is EVs. Since the power produced by DC sources fluctuates simultaneously and is not stable, converters are necessary to alter the power as needed. The potential of interleaved Single-Ended Primary Inductor Converter (SEPIC) technology to increase DC source voltage for EV applications is the main focus of this study. Given the inherent instability of DC power from sources, converters play a crucial role in regulating power output. A Proportional-Integral (PI) controller is employed to manage converter voltage, and optimization of PI controller parameters is achieved through Firefly optimization. The stabilization of the DC link voltage contributes to enhanced battery performance, making it a promising solution for the EV industry. The proposed work is simulated in MATLAB to validate the anticipated outcomes of the process.