US Patent 9444284 Bi-directional wireless charger

A bi-directional charging device includes a rechargeable battery, a coil coupled to the rechargeable battery, a selection mechanism that selectively causes power to be delivered from the coil to the battery and selectively causes power to be delivered from the battery to the coil, and a control mechanism. Upon determining that the coil is to provide power to the battery, the control mechanism causes the selection mechanism to selectively cause power to be delivered from the coil to the battery, and upon determining that the coil is to receive power from the battery, the control mechanism causes the selection mechanism to selectively cause power to be delivered from the battery to the coil.