A system comprising: a radio frequency transmitter configured to plug into an AC power outlet, and to transmit at one or more predetermined frequencies; and an electronic lockset for use with the radio frequency transmitter; wherein the radio frequency transmitter comprises a selector allowing a user to tune the radio frequency transmitter to a selected frequency from a plurality of predetermined frequencies and configured to change the selected frequency by cycling through the plurality of predetermined frequencies; wherein the selector comprises a manually-actuated switch configured to change the selected frequency by user actuation of the switch; and wherein the electronic lockset comprises: a locking device moveable between a locked position and an unlocked position; one or more energy consumption devices configured to actuate the locking device between the locked position and the unlocked position; at least one rechargeable battery configured to provide power to the one or more energy consumption devices; a battery holder configured to carry the at least one rechargeable battery such that the rechargeable battery is electronically coupled with the one or more of the energy consumption devices; and a RF energy harvesting circuit integrated into the battery holder, and configured to be electrically coupled with the rechargeable battery, wherein the RF energy harvesting circuit is configured to convert RF energy to a direct current power source for recharging the rechargeable battery, wherein the RF energy harvesting circuit includes an RF receiver, the RF receiver including a selector configured to allow a user to tune the RF receiver to match the selected frequency of the RF transmitter; wherein the electronic lockset includes a cavity dimensioned to detachably receive the battery holder. a radio frequency transmitter configured to plug into an AC power outlet, and to transmit at one or more predetermined frequencies; and an electronic lockset for use with the radio frequency transmitter; wherein the radio frequency transmitter comprises a selector allowing a user to tune the radio frequency transmitter to a selected frequency from a plurality of predetermined frequencies and configured to change the selected frequency by cycling through the plurality of predetermined frequencies; wherein the selector comprises a manually-actuated switch configured to change the selected frequency by user actuation of the switch; and wherein the electronic lockset comprises: a locking device moveable between a locked position and an unlocked position; one or more energy consumption devices configured to actuate the locking device between the locked position and the unlocked position; at least one rechargeable battery configured to provide power to the one or more energy consumption devices; a battery holder configured to carry the at least one rechargeable battery such that the rechargeable battery is electronically coupled with the one or more of the energy consumption devices; and a RF energy harvesting circuit integrated into the battery holder, and configured to be electrically coupled with the rechargeable battery, wherein the RF energy harvesting circuit is configured to convert RF energy to a direct current power source for recharging the rechargeable battery, wherein the RF energy harvesting circuit includes an RF receiver, the RF receiver including a selector configured to allow a user to tune the RF receiver to match the selected frequency of the RF transmitter; a locking device moveable between a locked position and an unlocked position; one or more energy consumption devices configured to actuate the locking device between the locked position and the unlocked position; at least one rechargeable battery configured to provide power to the one or more energy consumption devices; a battery holder configured to carry the at least one rechargeable battery such that the rechargeable battery is electronically coupled with the one or more of the energy consumption devices; and a RF energy harvesting circuit integrated into the battery holder, and configured to be electrically coupled with the rechargeable battery, wherein the RF energy harvesting circuit is configured to convert RF energy to a direct current power source for recharging the rechargeable battery, wherein the RF energy harvesting circuit includes an RF receiver, the RF receiver including a selector configured to allow a user to tune the RF receiver to match the selected frequency of the RF transmitter; wherein the electronic lockset includes a cavity dimensioned to detachably receive the battery holder.