I needed a light that I could run of my 12 volt battery system. I decided to make this led light out of an old case I had laying around. I cut holes in the top for the leds. I used 12 which is pretty bright. I have a resistor in series with the leds. I have one resistor for every 3 leds. I also added a switch for turning on and off. I connected banana plug adapters to the positive and negative outputs.