abnormally higher than the intensity of the generated current i 2 if yes is answered in step s21 and hence the intensity of the generated current i 2 is abnormally lower than the intensity of the load current i 1 or i 1 gt gt i 2 then the cpu 103a determines that there is either a shortage of generated power or a stopped engine status and goes to step s22 where it carries out a processing routine which will not be described in detail for suspending the operation of selected one or more than one loads depending on the power consumption rate of each of the related loads before it goes back to step s11 if on the other hand no is answered in step s21 and hence the intensity of the generated current i 2 is abnormally higher than the intensity of the load current i 1 or i 1 lt lt i 2 then the cpu 103a determines that either there is either a short circuiting in the supply line l1 or an abnormal charging on the battery 1 and goes to step s23 where it transmits an off control signal to the output port o1 to turn off the battery cut off relay 101 before it goes back to step s11 thus according to the first aspect of the invention the load feeding current sensor detects the sum of the load currents flowing to the respective loads as it is arranged at a point immediately upstream relative to the branch point for branching the power supply and the generated current sensor.