08-10-2014, 11:33 AM
Good morning to find ohms take deisred voltage drop divided by amps 12volts divided by .150amps(150millamps) equals 80 ohms. to find the wattage of the resistor watts = volts x amps 12x.150=1.8 watts. You want a safety factor of 3 to 5 so use 10 watts. Hope this helps. David