We often see the voltage reaching upwards
We often see the voltage reaching upwards of 15V or higher. The higher the voltage, the more current goes through the semiconductor, the more electrons jump from one side to the other, the more light is generated and MORE HEAT is generated. And, guess what is the enemy number one of LEDs? HEAT! We need to either control the heat produced or dissipate it. Apply a lot of current to an LED and you will get a very bright light for a very short period of time. Apply to little and you get a dim, useless light. That's what happened to you friends' LEDs. In this application of semiconductor physics, we know that the current measured at junction of the materials is proportional to the voltage supplied. Controlling the voltage and consequently the current is paramount to the life expectancy of your LED. Most inexpensive 12V LED cluster bulbs being sold today use a ballast resistor which bleeds off energy to limit the current. This ballast resistor limits current according to a simp...