A buck-fed current multiplier battery charging circuit can include a buck converter having an input configured to receive an input voltage and an output configured to deliver a regulated current, a current multiplier having an input configured to receive the regulated current from the buck converter and an output configured to deliver a multiple of the regulated current to a battery, wherein the current multiplier comprises one or more flying capacitor stages each including a resonant tank circuit; and controller circuitry coupled to the buck converter that operates switches of the buck converter to produce the regulated current and coupled to the current multiplier that operates switches of the current multiplier to deliver the multiple of the regulated current to the battery.