A power circuit includes a voltage limited charge circuit and a linear regulator to supply high current pulses to a load while maintaining a regulated output and not discharging the battery below a predetermined level. The voltage limited charge circuit includes a low impedance transistor and an operational amplifier that are together configured as an active loop. The transistor functions as a switch, and the operational amplifier provides an adjustable control voltage that adjusts the impedance of the transistor according to current battery voltage and a minimum threshold voltage. Adjusting the impedance of the transistor enables the storage capacitor to charge very fast when the battery impedance is low, or very slow when the battery impedance is high.