**IMPORTANT** - PLEASE TAKE NOTE: there may be an error in the DC power supply polarity markings on the power cable, and the red (+ve label) DC supply cable should be wired to the negative battery terminal, and the black (-ve label) DC supply cable should be wired to the positive battery terminal.  Please get in touch with us if you need any clarification on this. *** THIS ISSUE MAY HAVE BEEN CORRECTED FOR THE LATEST STOCK OF THE UNITS, SO MAY NO LONGER BE A PROBLEM. ***