LED questions for building mods...

[WindLvr]

Ok so I have these 5mm blinking LEDS that said they function at ~70milliamps. So running a 3.7v battery I did the math and came up with needing a 55ohm resistor to get the proper function out of the led. Yet not one light will shine??? Any Ideas? I have tried all kinds of different resistors and even ran a straight battery. I know current is going through because the led got hot when I ran straight battery. I know that one is fried now. I have a whole bunch of these, and want to use them in my next box mod. I want to light it like the Fourth of July!!! Any ideas how to get these LEDs to function properly would be great! Here is a link to the LED: Kingbright USA, an opto-electronic LED manufacturer products include all type of LED LAMPS , SMT LED, SMD LED, LED DISPLAYS optoelectronic components

 

[dragonriot]

My box mod was done with a 2v 80ma green 5mm LED and a 470ohm resistor from radio shack... the instructions I had were to use a 500ohm, but the Shack didn't have any. 55ohm may not be enough for your LEDs.

 

[WindLvr]

I tried the 470 Ohm resistors as well. Those are all I have tried. I wonder if because they work on any voltage from 3.7 to I believe 14 volts if I am just too low on the voltage.

 

[Slurp812]

Blue and White LEDs need around 4.1 volts to fire. The reds are like 2.something volts. Yellow and greens are a bit higher than red, but I believe in the 2.x range.

 

[twohandedcreations]

470ohm is what you need, if you used only 55ohm then you might not have had enough resistance and sometime LED's burn up when theres not enough resistance. so if you get the right resistor(470ohm) and the LED still doesnt work try a new LED.

 

[boneshark187]

make sure you don't have your positive and negative reversed. when you say it got "hot" when you connected straight to a battery you meant heating up as compared to the led illuminated...lol...just making sure

Also did you follow the precautions on page 5&6 of the spec doc:

http://www.kingbrightusa.com/images/catalog/SPEC/WP56BGD.pdf

 

[twohandedcreations]

If the LED got too hot, it will burn out.... If you hooked it straight to the battery correctly(pos. to pos.), even if it was too much power, the LED woulda turned on for a quick second then got hot and shut off. The longer leg is pos+ and to that you should connect either a 220, 330 or 470ohm resistor then the other leg of the resistor to power/pos+. Then connect the shorter leg of the LED to gnd-.

 

[WindLvr]

So the LEDs they sent me only work at 9volts. That's a bummer, but what can you do? lol...I have other uses for those! Back to the drawing board! I did get some awesome sample switches in the mail though. I can't wait to use though.

 

[classwife]

Moved to Modding Forum

 

[slimest]

WindLvr, according to datasheet, your LED' can safely work on voltage 3.5-14V. Judjing to datasheet, they have a zener diode inside. So a power dissipation depends on voltage. For 3.5V current is 8ma, for 8V (2 batteries power) current should be approx 35ma. As far as I understand, no need in a resistors because these leds have a built-in board.
If you are going to use these diodes constantly switched on, with 7-8V, you could use a small heatsink, as shown on datasheet. If these leds will work only occasionally (say, when your atomizer is switched on), or you will use them with 3.5-4V, no need in heatsink at all.
If your LED was ruined from a single lithium accumulator and even did not try to light, I can suppose that it was connected in reverse.
Datasheet: http://www.kingbrightusa.com/images/catalog/SPEC/WP56BGD.pdf