LEDs lifespan of 100,000 hours

I am tired of the LEDs vs incan debate and people suggesting a flashlight containing a LED with a rated lifespan of 100,000 hours is more reliable.

The way LEDs is constructed make it very rugged and ensure it is not the weakest link. However factors such as external contact wires, electronic circuits,etc are the weakest link and their failure would bring down the LEDs.
When LEDs flashlight failed in the field, frequently there is nothing much we can do to rectify the fault.

I had seem smoke rising from LEDs due to wiring errors and hear stories of LED going poof when people use the wrong rechargeable cell instead of the recommended primary cells.

The rated lifespan of a LEDs is not an indication of the lifespan of a flashlight.
We should be aware that flashlight either incan or LED based will fail and always have a spare flashlight.

That is a good point. Even the claim itself (100,000 hours) is not always true, especially with a highly overdriven 5mm LED. I think NewBie did a test and found that highly overdriven (I don't remember exactly how high) 5mm LEDs can reach %50 brightness before 1,000 hours.

The 100,000 hours is probably some statistical MTBF that was never meant to be implied as a number of hours of service life. However, it sounds really good as a sales tool.

Let a salesperson with a little bit of knowledge about the product overshpeel anything as "space age" technology.

As an example, consider the sales page for the Maha MH-C801D Battery Charger:

"Maha's unique "Digital Signal Processing" noise-reduction algorithms ensure that the signals do not cross talk." (Batteries cross-talk)?

"Even the circuit board is manufactured from a reinforced fiberglass material compound. " (All hard circuit boards are made from glass-epoxy laminate)

"This is especially true of the ones which claim that their chargers are lightning cool during their charge cycle" (Hehe, lightning is cool, hehe)

"manually-activated conditioning means that user decides when it is needed" (Thanks for clearing that up)

"Unlike some other models, the charger does not employ springs for the battery contacts that may fatigue over time." (Take another look at the spring action of the terminals my friend)

"The unit is designed to offer many years of service under demanding environments." (Well I guess I can install it in my wife's bathroom)

"The MH-C801D battery charger features fine contours that make it unlike any other battery charger on the market today. " (I can't wait to show those contours off to my buddies! They will go home and hate their sorry looking chargers!)

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If you let a flashlight sit for 100,000 hours (11 years), the copper parts inside will corrode and the rubber seals will dry up, and the plastic parts will get brittle. Flip the package over, most say "90 day limited warranty"

More information here:
https://www.candlepowerforums.com/threads/126857&highlight=degradation

Unless it is specified, the 100,000 hour life could well be true even if it is expected to lose 99.99% of its original brightness by then. It's just like the 50 hour runtime claims; they never said it was a useful amount of light at 50 hours.

Marketing doesn't just grab useless specs to push; sometimes they actually drive the engineering of useless features simply to have something to hype. I once saw an old package for a Monster Cable audio interconnect that claimed they used multiple tuned layers of superior RFI shielding to ensure that no extraneous signals could color the sound.

It was for an optical toslink cable.

I love marketing hype, kinda reminds me of media sensationalism....

I think firefly's original point was that the LED's lifespan has nothing to do with its durability or suitability for hard use. And he's absolutely right. The dubious 100k hour claim is often accompanied by statements such as, "Long-lasting LED never needs to be replaced!" They don't say, "Unlike common incandescent bulbs, it's difficult or impossible to replace in the field, and we don't even give you an extra!" They are generally more shock resistant, but I've seen a Luxeon come apart too (direct hit).

Unfortunately, the 100k hour issue is unlikely to go away. As manufacturers begin marketing LED fixtures to replace fluorescents, they're going to need any edge they can find.

Has anyone actually had their led's drop power or burn out?

Yes, especially when overdriven.

Besides the data I posted earlier, here is a prime example of reality:
https://www.candlepowerforums.com/threads/128801&page=7&pp=30

The reason most LEDs fail prematurely is that they are not properly used. The technology is very robust. Silicon encapsulated LEDs are proven to reach 50,000 hours at 70% of initial lumens. They can last 100,000 hours or more if one can tolerate additional dimming. Epoxy encapsulated white LEDs dim far faster, but it appears that Seoul Semiconductor at least has solved that problem. Colored LEDs used in 7 segment displays last decades, in many cases well over 200,000 hours, while still retaining usable brightness. Naturally, if an LED is overdriven beyond specs, or if the driver electronics are poorly designed and fail, then the LEDs will no longer light. However, don't blame the LED itself for this. Blame the designer who didn't know what they were doing. For example, I still see people asking what voltage a white LED runs at. I still repeat ad nauseum that an LED is a current-driven device. At the very least you need a resistor between the power source and the LED. For best life you should have a constant current driver. And in any device where longevity or reliability is a concern you should never exceed specs. That means 20 mA or less for 5mm LEDs. Follow these guidelines and the LED will likely outlive you.

To anyone who complains LEDs don't last 100,000 hours I always ask them to find me a light source which is longer lasting, less expensive, as easy to drive, and as efficient. For colored light there isn't one. Even for white light we have sources which can last up to 50,000 hours (i.e. fluorescents) but they have more complex driver requirements and often dim significantly way before they fail. We have cheaper sources (i.e. incandescents) but their lifetime and efficiency are miserable. We have more efficient sources (fluorescent and HID) but again with more complex driving requirements, and they are just about in the process of being overtaken by LEDs in efficiency anyway. White LEDs still cost more than alternatives, but give it a few years for that to no longer be true.

jtr1962 said:

The technology is very robust. Silicon encapsulated LEDs are proven to reach 50,000 hours at 70% of initial lumens. They can last 100,000 hours or more if one can tolerate additional dimming.

Naturally, if an LED is overdriven beyond specs, or if the driver electronics are poorly designed and fail, then the LEDs will no longer light. However, don't blame the LED itself for this. Blame the designer who didn't know what they were doing.

an LED is a current-driven device. At the very least you need a resistor between the power source and the LED. For best life you should have a constant current driver. And in any device where longevity or reliability is a concern you should never exceed specs. That means 20 mA or less for 5mm LEDs. Follow these guidelines and the LED will likely outlive you.

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Totally agreed, silicon encapsulated LED are very tough. But the driver electronics even if well design are often not encapsulated. Hence the circuit is exposed to the environment and increase the chance of failure.

Not blaming the LEDs for premature failure. Since it is too tempting for the designer not to follow spec and overdrive the LED for increased brightness at the expense of longevity and reliability.

When buying a flashlight, we need to look at it as a system of components working together to emit light. Reliability of the entire system is more important than the superiority of any individual components.

PS: Even a fully encapsulated device like the Glo-Toob will fail if wrong voltage is supplied. Imagine connected to a 15V DC supply instead of A23 cell.

EngrPaul - ROTFLMAO. Well played sir!

Fireflay99 - Forgetting the 100K hour bit it seems clear that all things being equal the LED is still clearly the more robust and reliable light producer.

Disregarding overdriving etc - when driven at spec LED's last longer, are more durable and are more efficient than incandescents. If we take overdriving into account remember most incandescents can barely additional voltage without going poof while this forum is proof that most LED's can take some pretty serious overdriving. Look at the '7W-16W' LED flashlights flooding out of China these days - they're driving their emitters way beyond spec, making tons of light and when the lights do fail it's not because the LED burned out in my experience.

Regarding a backup light I agree with you 100% - PPPPP.

I have, and you have too.

The first one I found was a power led on an air purifier I have. It's been dimming for years. It's now almost dark after 9 years of constant running.


Second is... the numlock light on my keyboard. It's noticably dimmer than the seldom-used capslock.

EsthetiX said:

Has anyone actually had their led's drop power or burn out?

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firefly: I understand exactly what you mean. I had a flashlight die on me with no more than 10 mins of normal use because the output diode burnt out. The LED was driven at not much more than 1W.

Adding in a question here. Should I expect that electrical components (diodes, capacitors, resistors,) made in China would be less reliable than similar components made in the US or made under US designs? I'll also ask, are there any flashlight manufacturer besides Surefire that uses exclusively US made components?

Maybe this thread belongs in the general section.

Originally Posted by EngrPaul
That battery charger page is hilarious! "Users often are confused by the various solid, flashing, red, green and yellow displays on traditional LED battery chargers." It took me forever to figure out that RED means it is not ready, and GREEN means it is.

Despite the rediculous "Sharper Image" type text it looks like a really nice charger.

I don't mean to hijack this thread, but that needed to be said.

Bernie

Many lighting sources are rated for service time to reach a certain dimming percentage. Anyone who evaluates street lighting, for instance, knows from the manufacturer how long it will be before high-pressure sodium (or whatever) fixtures will become dim enough to require replacement, and will evaluate and budget accordingly. All of this assumes that the fixtures will be used as manufacturers specify, and anything equivalent to "overdriving" (or otherwise changing the manufacturer's specified parameters) can be expected to alter the predictive ratings.

Once LED light sources begin to be marketed for commercial purposes that involve capital spending and budget planning, you can be sure that manufacturers will become more rigid in developing ratings and standards that can be relied upon. Any fudging will make a manufacturer potentially liable, and will almost certainly harm their position in that market.

We CPFers generally have different goals from the "capital spenders". We will gleefully overdrive our LEDs and incandescant filaments to experience the joy of increased illuminating power. They (the PHBs) take great joy in reducing risks and controlling costs in an effort to maximize the earnings from capital investment.

What's more, I'd guess that for the majority of people here, it's not even mechanical failure, let alone diminishing LED performance which will cause a light to be replaced but "obsolescence" - in other words new, better LEDs, which at the moment appear to be on a Moore's Law trajectory - when that levels out due to physical limitations I guess we might care more.

jtr1962 said:

... Silicon encapsulated LEDs are proven to reach 50,000 hours at 70% of initial lumens. They can last 100,000 hours or more if one can tolerate additional dimming. Epoxy encapsulated white LEDs dim far faster...

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Is there an easy way to tell what the LEDs in my lights are encapsulated with? Which flashlight manufacturers commonly use silicon?

Thanks

LED_Thrift said:

Is there an easy way to tell what the LEDs in my lights are encapsulated with? Which flashlight manufacturers commonly use silicon?

Thanks

Click to expand...

Any power LED like a Luxeon, Cree, or Seoul Semiconductor is silicon encapsulated. 5mm indicator LEDs are epoxy encapsulated. Basically, if you're getting a lot of light out of a single LED as opposed to an array of many LEDs then it's silicon encapsulated.