This paper presents a comparative evaluation of passive and active damping techniques for LCL filters in bidirectional onboard chargers (OBCs) used in electric vehicle (EV) applications. The investigated system consists of an LCL-filtered Active Front-End (AFE) converter, an 800 V DC-link, and a bidirectional non-isolated DC/DC stage interfacing with a 360 V lithium-ion battery, enabling both Grid-to-Vehicle (G2V) and Vehicle-to-Grid (V2G) operation. The LCL filter is designed to satisfy harmonic attenuation and reactive power constraints, with the resonance frequency targeted near 1.2 kHz. Three passive damping approaches—series, parallel, and R–C branch damping—are analyzed and compared with active damping based on capacitor-current feedback. Transfer-function modeling and Bode-plot analysis are used to examine resonance characteristics, while time-domain perturbation tests in MATLAB/Simulink evaluate grid-current quality under both power-flow directions. The results show that passive damping effectively suppresses resonance but may introduce additional losses or reactive power variation. Active damping provides the best THD performance and maintains stable operation under bidirectional conditions, although at the cost of increased control complexity. The study highlights the trade-offs between damping effectiveness, implementation complexity, and grid-compliance constraints, providing practical guidance for the design of robust LCL-filtered EV onboard chargers.