Thanks in advance for any replies. I have searched here and the internet over and over again and have not found an answer I understand. I am trying to power a single 3w, 2.2FV, 700ma cob LED with a car battery system. So I imagine 13.8 volts when running. I have used the resistor calculator and it says use a 18 ohm 7.4v resistor. Is this true and do they make such a thing? I cant find anything close. I initially used a 330 ohm resistor to test because I read that somewhere and the resistor burned up. Please help me if you can.