Mobile devices are usually energy-constrained. In order to avoid exhausting energy and lose the network connection, the idea of transferring power to mobile devices wirelessly via radio signals has recently gather much attention. In this paper, we consider the scenario in a point-to-point communication system that the transferred power is used for the receiver to feedback the quantized channel state information (CSI) to the transmitter. The transmitter then utilizes the CSI to beamform the signals. Although feedbacking more bits yields better CSI, it requires more power and a larger portion of time spent on the wireless power transfer, affecting the overall achievable rate. We derive bounds of the average achievable rate of the forward channel and investigate its relation to the average transmission power for wireless power transfer and the quantization bit number.