Abstract: Controlling a charging current while transferring energy from a source battery to a target battery in an electric vehicle (EV) includes operating, by control circuitry, a buck converter at a fixed switching frequency to transfer power from the source battery to the target battery, in a first operational mode; in response to detecting a first trigger event, transitioning from the first operational mode to a second operational mode to operate the buck converter at a variable switching frequency; and in response to detecting a second trigger event, transitioning to a third operational mode to activate a boost converter coupled to the source battery and the target battery.