A portable power supply apparatus is provided having reduced impedance losses. The portable power supply apparatus is comprised of: a portable housing; a battery system residing in the housing; and an inverter circuit residing in the housing. The battery system generates a direct current (DC) voltage having a magnitude greater than or equal to a peak value of a desired alternating current (AC) voltage. The inverter circuit receives the DC voltage directly from the battery system, converts the DC voltage to an AC output voltage and outputs the AC output voltage to one or more outlets exposed on an exterior surface of the portable housing.