primary power is provided to the irrigation controller in accordance with the present invention by photovoltaic module pvm 1 or alternatively by a powerkey u2122 power source the powerkey u2122 power source is a battery that is connected between terminals bat and bat during programming of the irrigation controller 1 the powerkey u2122 power source not shown is always connected thereby the battery provides the considerable power necessary to energize the display lcd 1 and importantly operate the entire controller 1 at the high duty cycle necessary to conduct communications with the operator the battery also serves to initially charge the capacitor power storage both at a current limited rate each time the powerkey u2122 battery power source is replugged to its receptacle 14 shown in fig1 and 2 this insures that after each user interface communication the controller is always left in a fully charged condition during normal quiescent operation all low power cmos circuitry and the low power valves are energized by energy stored in supercapacitors supercaps sc1 sc2 it is the function of first asic u1 to manage the voltage and power levels of the irrigation controller and most particularly to control the charging of supercap sc1 sc2 by pvm 1 and the powerkey u2122 power source the supercaps sc1 sc2 will automatically be charged by connection of the powerkey u2122 power source the asic u1 operates to control this charging through a constant current source implemented by transistors q3 q4 and resistor r2 this constant current source is controlled by a switching regulator.