Thread: LED's... rare to burn out?

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I bought a pair of those little "Lite-n-Bolts" to illuminate my license plate, which basically consists of a tiny LED bulb epoxied into the head of a bolt with the wires coming out the end of the threads. They worked great for about 3 weeks and now one is already seemingly burned out... I checked the connections and everything looks good there, but no light. I thought I read that LEDs were supposed to last for like 10,000 hours or something? If its any concellation, the guy I bought them from is going to send me a free replacement...just wondering if anyone else has had experiences with LED's going south? All my other "old fashioned" bulbs on the car are working fine.

you've got either a really cheaply produced LED or a rare burnout. Anything can cause any electrical burn out but on the average, LEDs keep going and going and going....sounds like I've heard that commercial before.

An LED will burn out pretty quick if too much voltage/current is applied to it. I don't know how the bolts are setup but they would need to have a resistor and/or a number of stacked diodes in series with the LED. Used to be most LED's had a 1.5V forward drop and could handle something on the order of 25-50mA but I'm sure these have changed a bit with some of the newer technologies. I figure it would need at least something like 250-500 Ohm resistor in series with the LED if powered off 13.5V.

2 cents

-Chris

I buy the led lights that plug into a cig light to light up console they have a little board in them and they only last about 3 months

Denny there the blue ones with a clear bulb also .

Good info Denny, nice to know my memory ain't completely shot

-Chris

In other words, the tiny LEDs that I will be using for turn signal and high beam indicators may well need a 200 to 500 ohm resistor to survive. That is, unless they already have a resistance built into them. And, if so, how do I tell if the do have that resistance. For sure my supplier wont know. Why do places like Yogi's or Yearwood sell these lights without some sort of information. I am well aware of the fact that my LED turn signal light bulbs need a resistor to operate the flasher and my Pontiac style tailights have a built in board to operate 30-40 LEDs, but I'm a lowly nut-and-bolt ME, not a EE that plays with unseeable and nebulous volts and amps. Sheesh

Originally Posted by DennyW

Heres a quicky calculator to give you an idea, and figure what you need for a resistor. You can buy the led's that have the resistor built in. Some times the problem with that is, they figure you are using 12 volts, and do not consider the auto out put voltage of 14 volts. As a result, the led's die young.

Oh, and try not to run them in series.

http://www.hebeiltd.com.cn/?p=zz.led...tor.calculator

Thanks Denny,
I guess I have another homework assignment. And a trip to Radio Shack for some resistors (Might almost be easier to source replacement LEDs that I KNOW are right for 14+ volts). The LEDs are run as a single item from the system wiring and not in series so each will require a resistor, the same as my directionals.