Are LEDs really all that durable?

[Genxsis]

I just read another thread on the forum that got me to thinking maybe LED isn't all that it's cracked up to be: http://www.candlepowerforums.com/vb/showthread.php?t=168462

Ever since I've heard about how LED is so long lasting and nearly unbreakable, I thought having some LED lights is all I'll ever need and I can always count on them. But now I read that they go out when dropped, and sometimes they just die after a short time for no seemingly good reason. So now I wonder....

Who here has had an LED light fail on them?

 

[Melkor]

I've had one LED of a 3 LED cluster stop working within like a month. That's it for me. My oldest LED light (a Rayovac) is about 5 years old and its LEDs are holding up just fine.

 

[Genxsis]

Was that 3LED cluster the Nite Ize minimag upgrade? I have 2 of those.

 

[Tjin]

i think the problem isn't really the LED's them self, but there driver circuits (or sometimes the lack of one) and general build of the light.

 

[mossyoak]

yeah that wasnt the leds fault that was a bad design, look at arc AAA's and some surefire led stories they are very durable.

 

[Melkor]

Nah, it was some light by Optronics or something like that. 3 LEDs, twist on/off, 3AAA, had a little clip on the back for clipping to things, got it at wal mart.

 

[OhMyGosh]

I have a couple of LED map lights that plug in to a car cigarette lighter. They burned out. 100 ohm resistor was to low if the car is running. LEDs will last a long, long time if used properly, but they are subject to abuse like anything else.

This is why I don't like the idea of running Cree/SSC at 1 amp. I think it is pushing the limit and will cause it to degrade faster. Hardly brighter than 700-800 mA anyway.

 

[yellow]

I never had a light using ONE SINGLE of the better led fail,
Most any cheap light with multiple 5mms has several dead ones after just a few sets of batts

- so its the same with incan --> VERY cheap = sux

 

[BB]

Newbie a while ago did a very nice thread on LEDs and found that some of the earlier LED lights when overdriven degraded in output within a few handfuls of hours.

The first white LED's were not that bright so folks thought if you took a 100,000 hour white LED and over drove it by 2x, even if it lasted only 10,000 hours, folks would be happy. But--in real life, these LED's quickly degraded in output. (tried to search for thread with a sectioned white LED with brown damage in the phosphors right next to the die--but I did not find it).

So--there was (and still is) some bad experiences with LED's that were caused by improper use (overdriven, poorly heat sinked, no regulation, mechanically unsound mounting/manufacturing, etc.).

-Bill

 

[asdalton]

Many of the early claims for lifetime were exaggerated, especially for 5mm white LEDs. The "100,000 hour" lifetime is actually 5000-10000 hours when driven at 20 mA, which hardly matters in a flashlight--except that most manufacturers were overdriving their LEDs from 40-100 mA, where noticeable degradation occurs over hundreds or even tens of hours.

An example of an overdriven, trouble-plagued flashlight is the Streamlight Propolymer 7-LED (not Luxeon).

Power LEDs like Luxeon and Cree are designed with heat dissipation in mind, and their lifetimes in a well-designed flashlight will be longer. There's also less temptation for manufacturers to overdrive them, since they have high output when running in their spec range.

Running any LEDs on poorly filtered car or house electricity--both of which contain spiky waveforms--will also shorten their lifetime drastically. (And it's not just LEDs; I ruined two cell phone batteries by using a car charger.)

As other people have commented, LEDs of any type need to be run within their designed limits. The driving circuit can make or break the overall reliability of the light.

 

[cave dave]

Let's see, for me:
3ea Arc Failures
1ea Surefire U2 Failures (selector ring)
3ea CMG Infinity Failures
0 Maglight failures

 

[mossyoak]

youve never had a bulb blow in a maglight? because that would be a failure.

 

[cave dave]

youve never had a bulb blow in a maglight? because that would be a failure.

That's not a failure that's a consumable like replacing batteries when they die. But no I've never had one die prematurely or from a drop.

 

[jtr1962]

I've been working with LEDs for over a quarter century, although only in the last 5 or 6 years have they become bright enough to use as light sources instead of just indicators. In all that time the only failures I've had have been when I didn't drive the LED properly. I'll grant that most white epoxy-encapsulated LEDs don't live up to the 100,000 hour life claim, but most of the other colors do. And silicon encapsulated whites can live for 100,000 hours or more if properly driven and heat-sinked. I have a Q-bin luxeon in my workroom running at 350 mA for over 3 years, 6 months (over 30,000 hours) so far. It has dimmed less than 10%.

Almost all premature LED failures are user error. They really are durable if driven and heat-sinked properly.

 

[victor1]

I've had 2 Mini Maglite LED lights fail on me. The first worked fine until the 4th week. After I exchanged the first, the second one went 2 weeks later. They both had the LED turn off after running for 3 minutes or so. After letting it cool, it worked but the problem persisted. It seems the problem is with the controller circuit.
Has anybody else had this problem with mini mag?

 

[TorchBoy]

I bought my first white LED wayyy back in 2001 when 5600mcd of white(ish) light was amazing. Since then I've only had a single LED fail in a torch, and that particular LED was looking sick to begin with. So yeah, I'd say they're quite robust if they're OK quality to start with. I have much more confidence in them than similar intensity incan bulbs.

Of course I've burnt out the odd other LED while playing around with them, and one time I bought a dozen or 20 and returned the lot because they were pathetically dim and green, but that doesn't really count for the question posed in the first post.

 

[TorchBoy]

(And it's not just LEDs; I ruined two cell phone batteries by using a car charger.)

Spikes wouldn't be good, but don't car chargers generally try to charge cellphone batteries faster than normal?

 

[o0o]

LEDs themselves are pretty durable. It is the connections and/or circuits that can fail. After having TONS of problems with Chinese lights (circuits breaking, LED emitters falling off the board, etc...) I've staying away from Chinese lights. Only Fenix has earned my trust, but never to the trust level of Surefire.

I've even had expensive Chinese lights fail due to circuits and/or other QC issues...

 

[2xTrinity]

I've been working with LEDs for over a quarter century, although only in the last 5 or 6 years have they become bright enough to use as light sources instead of just indicators. In all that time the only failures I've had have been when I didn't drive the LED properly. I'll grant that most white epoxy-encapsulated LEDs don't live up to the 100,000 hour life claim, but most of the other colors do. And silicon encapsulated whites can live for 100,000 hours or more if properly driven and heat-sinked. I have a Q-bin luxeon in my workroom running at 350 mA for over 3 years, 6 months (over 30,000 hours) so far. It has dimmed less than 10%.

If you are talking about underdriving lighs sources dramatically, then even incandescent lamps can have extremely long lifespan. For example, there are a handful of bulbs that have been on almost continually for nearly a century. We personally have had some incandescent bulbs on a dimmers in use every day (for hours a day) for nearly 20 years without a single burn-out (as they are always soft-started, and rarely run at 100% output). Of course, the difference between LEDs and incandescents that incandescents are very very inefficient when underdriven, and LEDs are most efficient when underdriven.

Ultimately though, the biggest enemy to LEDs is heat. Overdriving directly produces heat, but poor heatsinking, even with a more normal drive, can cause just as much degradation. IMHO every LED flashlight should have thermal protection -- all that is really needed is a temperature-sensitive thermistor in parallel with the current sense resistor, that is what the MagLED module does to dim itself in order to make up for its lack of heatsinking. I have had some of my best heatsinked lights still get extremely hot due to inadvertent activation inside an insulated jacket pocket.

 

[TorchBoy]

... even incandescent lamps can have extremely long lifespan. For example, there are a handful of bulbs that have been on almost continually for neraly a century.

Perhaps by chance there was a news story on the telly last night about a Hungarian guy with a bulb his (grand?)father used in World War 1. And it was still going. I tried to find the story just now but didn't find anything other than references to a Hungarian lightbulb factory back then that was known for making long life bulbs.