A method of operating an access control system connectable to a power supply, including the steps of comparing the supplied power voltage to a threshold power supply voltage, determining a power-good condition when the supplied power voltage exceeds the threshold power supply voltage, determining a power-fail condition when the supplied power voltage does not exceed the threshold power supply voltage, and in response to the power-good condition: charging a capacitor to a capacitor charge not less than a threshold charge, and thereafter powering an electromechanical actuator, transitioning the access control system to a first state selected from locked and unlocked states wherein the capacitor charge is not less than the threshold charge upon completion of the transitioning, and in response to the power-fail condition: powering with the capacitor the electromechanical actuator and transitioning the access control system to the another of the locked and unlocked states.