While RF energy harvesting has proven to be a viable power source for low-power electronics, it is still a challenge to obtain significant amounts of energy fast and efficiently from the ambiance. Available RF power is usually very weak, resulting in a weak voltage applied to a demodulator to drive it into a region of significant nonlinearity. An RF energy harvesting system consisting of a rectenna, a dc-dc voltage converter, and a novel battery cell is proposed. The rectenna is an integration of an antenna and rectifying diodes. In addition, a switched-capacitor dc-dc voltage converter is integrated on a silicon integrated circuit with energy transfer efficiency as high as 40.5%. A new battery system that can be recharged at low voltage (<; 1.2 V) is demonstrated. In this brief, all of these elements are tested as a system to achieve RF battery recharging from a commercially available hand-held communication device. The system exhibited an overall harvesting efficiency of 11.6%.