Abstract: A power source particularly for use in remote locations which can be operated off of conventional sources of power such as off a battery source, said power source including means for distinguishing between different voltages and including means to indicate when power has been reduced from the power source or battery below a safe level for taking additional power therefrom. The device also includes means for preventing a polarity reversal from causing damage and it includes adapter means by which the subject power source can be plugged into a conventional receptacle such as into a cigarette lighter receptacle on the dashboard of an automobile or similar device. The subject device is particularly suitable for use by campers, emergency crews, and others who need power at remote locations and from a conventional source of power such as from a vehicle battery.