A tapped-inductor boost converter for an input voltage range of 0.3-0.6 V with the output connected to a fixed voltage of 24V for battery charging, was designed, analyzed and tested experimentally. The converter is intended to be used as a harvester for low voltage renewable energy sources such as thermoelectric generators and bio-reactors. The proposed converter is capable of achieving a high boost ratio (40-80) with a reasonable duty-cycle (0.3-0.7). The converter was optimized by selecting low parasitic resistance components and by applying a PCB-based flat magnetic core to reduce the leakage inductance. The operation of the proposed converter was analyzed for continuous and discontinuous inductor current modes and power loss and efficiency expressions were derived. Good agreement was found between circuit simulations, theoretical analysis and experimental results. The experimental unit reached an efficiency of about 86% (gate drive losses included) at an input voltage of 0.5V and output power level of about 1.2W.