We propose a charge pump type of supercapacitorcharging circuit for energy harvesting application to perform maximum power transfer tracking (MPTT). The charging circuit supplies a train of current pulses to charge an energy-storing supercapacitor array to a doubled voltage, converting input power obtained from ambient energy sources. The connection of multiple energy storage supercapacitor is reconfigurable by means of a simple switch array. The voltage doubler charge pump and the smart switch array not only enable the sensor nodes to operate under low ambient power conditions but also improve the charging speed. The operation of the supercapacitor charging strategy was validated by simulation.