To realize the concept of smart parking for electric vehicles (EVs), the development of a bidirectional battery charger with a smooth transition capability from one operating mode to another is imperative. Keeping this in context, this work realizes a bidirectional battery charger with smooth operation transition capability by utilizing a static-transfer-switch (STS) also termed a synchronization switch in this work. In addition, a modified Lyapunov demodulator-derived control algorithm is employed to achieve a smooth transition of operations at non-ideal grid voltage conditions. The merits of utilizing the Lyapunov demodulator are accurate amplitude and frequency estimation of the grid voltage at ideal and non-ideal grid conditions. Therefore, the smooth transition of operation is carried out. Moreover, the accurate frequency estimation is helpful to generate the grid voltage template under ideal and non-ideal grid conditions both. Furthermore, this demodulator algorithm is utilized to estimate the fundamental component of the load current. Hence, the power quality of the battery charger conforms to the IEEE-519 standard throughout the bidirectional operation. The operation, and performance of the designed battery charger are validated through the simulation. At last, the effectiveness of the charging operation and V2G operation both are tested, and obtained results are analyzed.