LED Help.....Is this correct???

skeeler · Newbie Joined: 11 Aug 2005 Posts: 23 City: Omaha

Hello all!! Thought I would run this past all you tech junkies out there. I just wanted to make sure I had the wiring correct before I go to the install phase. I am adding some LEDs to the interior of my boat. All the LEDs are 2.1volt, add the current provided will be 12volt, also the LEDs are rated to 30ma. Is the wiring digram I made below correct?

Jensen · Posted: Aug 17, 2005 2:42 pm Post subject:

ya, that looks right. but i would personally use 100 ohm resistors, since the min forward voltage is 2.1, and the max is 2.5, i would pick somewhere in between, so if you use 100 ohm resistors, the leds will be powered at 2.3v so you'll get a bit more kick out of them.

your soldering these together right?

AndyDeeJay · Outlaw Joined: 20 Jul 2004 Posts: 239 City: Belfast

If the alternator is kicking out 14.5V max and you take the forward volt drop across the series load to be 10V then you will need to drop 4.5V in the resistor. The curent is 0.030A. R=V/I. R=4.5/0.03, R=150ohms

If you go down to 120 or 100 you might cook those LEDS. Put is 150Ohm to be safe.

P=VI= 4.5x0.03 = 0.135watts. Use 1/4watt resistors.