Service Life of 5W LEDs

Recently I checked out the site of a flashlight manufacturer where they listed the service life of their 1W LEDs as 100,000 hours, but only 500 hours for the 5W lights. Just wondering if this is typical, and if it implies that I should take it easy on my U2 and use the KL1 for routine things.

Granted, 500 hours is also about the service of the typical outboard motor, but lights are potentially used alot more than a motor. Does Surefire also contend their 5W lights are only good for 500 hours?

This point about the 5W or rather, LuxV, LEDs has always seemed to come as a shock to newbies. I suppose it's because the 5mm LEDs have always been advertised as having 100,000 hrs service life.

Heaps of information available for the price of a search, but for your convenience...

Yes, white LuxV have a service life of 500hrs. (The monochromatic LuxV have service lives similar to any other LED). This means that on average your white LuxV will be half as bright at 500hrs as when it was new. This is due to the heat created by the package. Heat is bad for the phosphor that produces the "white" light, and the LuxV package produces copious amounts due to the close spacing of what is basically 4 of the 1W dies. I'm sure if you could spread out the 4 dies, they would last as long as the normal LuxI.

So anyone using LuxV in the flashlight will be subject to this service life, even Surefire. Much worse will be those that aren't able to dissipate the heat well.

BTW, the way most 5mm LEDs are driven, i.e., directly from 3 1.5V cells with no current limiting resistor, or over-powered, or with high peak voltage pulses, their service life will not reach 100,000hrs either.

And another point that quite a few CPFers will claim is that 500hrs is actually quite a long time for handheld flashlights. They will talk about having to go through X number of CR123, being equivalent to Y amount of money, etc.

That is acceptable from one perspective, but totally beside the point from another. 500hrs is 500hrs, and depending on your style of use, you could chew through that quite quickly. And you won't feel the pinch on your hip pocket if you are running rechargeables.

Thanks for the summary. I will do some searches on this.

I wonder about the service life of my WX1S Luxeon V in my Mag. The large hotlips heat sink and large mass of aluminum of the Mag keeps it running cool. Considering I using don't run it at max 700mA output with the nFlex board it should last much longer.

My question is concerning the amount of watts it runs at. I used a benchtop power supply and the Vf was 6.10 volts at 700mA for a total output of 4.27 watts. Now consider the Vf of Luxeon V's drop up to 0.5 volts during the first 50 hours of use... that would put it at a maximum of 4 watts when running at the highest setting.

The LuxeonIII runs around 4 watts when driven at 1,000mA and are rated for 20,000 hours when doing so. Can I expect my WX1S to have close to the same life since it is running at basically the same wattage?

I can understand a UWAU (~8.5 volts or so) so Luxeon would rate the "6" watters as worse case 500 hours. My S rank for voltage is around 6 volts or 4 watts so I lean towards at least 2,000 hours. The 4 die will give less of a hotspot so it should technically transfer heat better to the heat sink.

It might take 5 years of use to get 500 hours of high 700mA levels of light out of the thing. I normally am running much lower so I might never find out in the real world. Plus, the real world should have 400 lumen LEDs out in the next few years.

Just something I was pondering...maybe the phospher will smoke when producing an average of 170 lumens for that bin. Hmmmmmmm.....

I think 500 hour life assumes light is generating normal Lux-V heat. If the light is underdriven (like a SF U2 on settings 1 and 2), I don't see how the light only lives 500 hours to 50%. It can't possibly generate that much heat at setting 1 or 2, right?

This question has been asked dozens of times.

There are several issues with the Luxeon V Portable.

It's a series-parallel design. Even with very tight Vf matching, it's possible for one (or more) of the dies to shift Vf, increasing current flow through one string that could kill it - to be followed by the other in short order.

The other issue is phosphor degradation. Heat is very bad for the yellow phosphor. 5W of heat seem to be more than the Luxeon V package can gracefully conduct away from the phosphor. Even though the LED dice will probably continue to work fine after the phosphor is shot, the output will be very dim.

That having been said, 500 hours is what Lumileds will warrantee. There are plenty of people that have gotten well over 500 hours from the Luxeon V Portable.

Somewhere I saw quoted an electrical engineering "rule of thumb" that for every 10 deg centigrade increase in temperature, the expected lifetime of an electronic part might be expected to halve.

If the LuxV will conform to this rule of thumb, just running it on level 5 most of the time instead of level 6 will probably increase its expected lifetime by manyfold, since halving the power to the LED probably results in a die temperature many tens of degrees lower than running it at the full 5 watt rating.

I have a question.

When are we going to see significant performance improvements in the Luxeon-V?? Such as much longer led life in the portable white versions, and also greater output?

@357. Conventional wisdom is that Lumileds' future product development will be concentrated on the Lux-IV. It's been speculated that Lux-V might even be discontinued. This makes a fair bit of sense as the Lux-V is the 'Windows ME' of Luxeons anyway...

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enLIGHTenment said:
@357. Conventional wisdom is that Lumileds' future product development will be concentrated on the Lux-IV. It's been speculated that Lux-V might even be discontinued. This makes a fair bit of sense as the Lux-V is the 'Windows ME' of Luxeons anyway...

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So, what will the Luxeon IV be like? A cross between a III and V?

Other other thing that seems strange, why go backwards to Luxeon IV? Why are they not considering Luxeon VI?

In regards to Windows ME, that was if I remember a very bad and buggy program. Is the Luxeon V really bad and buggy for a Luxeon product? (aside from the runtime issues)??

The Luxeon 4 is supposed to be a more effiicent version of the Lux 3 with better heat dissipation characteristics and a higher allowable forward current.

Lux IV was a badly botched product from the beginning. Lumileds promised 100 lumens from a single die but couldn't deliver. They opted to pack four dies, in a series-parallel arrangement, onto one carrier and pretend that it was a good idea. The result is a 500 hour lifespan, a source that can't easily be focused, and a spot heater all in one package.

The question being asked is ongoing and seems to me flawed? I mean if you buy something which says it has a finite life then if it goes on for longer great and if it dies quicker, complain and get a replacement!

The Lux V does what it was designed for and provides a high level of light. whether it is flawed or not is subjective, it MAY last much longer then its rated 500 hours and Lumileds are still considering revising that MTF to a longer period of time as data becomes available.

Dont forget many companies use this LED in their products and are fully up to speed on its specs. They, and I, are happy to accept its limitiations.

Doug

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idleprocess said:
That having been said, 500 hours is what Lumileds will warrantee. There are plenty of people that have gotten well over 500 hours from the Luxeon V Portable.

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Great observation. They may be revising it too. Also, don't forget, if you actually chew up 500 hours (easy with 18650 lithium ions) and the light dims noticeably or malfunctions, contact Surefire and ask what you should do.

We will be very interested in their response. I have no doubt they will do the Right Thing (replace/rebuild it) as well.

With all the L4s in service in CPF since 2003 (think it was a winner of the CPF Luminescence Awards too), not a single one has been documented as having died of old age, or even reported. The L4 and Pila rechargeable combination is a very well known and popular one (I use a 17670, ie. unprotected equivalent), and it's very easy to put hours and hours of usage on it. In fact they say lithium ions are only supposed to be rated for 500 charge cycles - 500 hours if you run them with the L4.

Furthermore, the L4 gets a LOT hotter than the U2. It's not "it has better heatsinking because it gets hot". Heatsinks work by RELEASING heat to the air. There are two kinds of heatsink - one that remains cool to the touch because it is not soaking up the heat in order to release it, and the other kind that is releasing heat to the air very quickly and thus remains cool. If the amount of heat going into the heatsink is > than the amount of heat being released, temperature of the sink (and the connected system) will rise.

The L4 runs hotter, basically, and thus if heat kills, would therefore be more likely to exhibit symptoms. I'm quite glad to note that no visible, obvious decrease in luminous output or field failures of the emitter attributable to long runtimes have been observed - especially since I own an L4 and a U2 /ubbthreads/images/graemlins/wink.gif

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The Lux V does what it was designed for and provides a high level of light.

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Well... /ubbthreads/images/graemlins/smile.gif Actually, it didn't do what it was designed for. So Lumileds moved the goal post. /ubbthreads/images/graemlins/wink.gif

steelwolf said it well.

how about a LUX developed on a heat pipe, and a large copper heat sink.
something with 12 gates that can handle .5A each, a heat pipe up the center of it, and epoxy lens all around it.
have it be just like . . . just like a Bulb , but with the caveat of having a large round base at the bottom.

the Lux 105 Saucer
mabey they would have to redesign that machine that pumps them out at 500 a minute though.

Time will tell. Let's wait another year and see if any of our Lux V toys die. I try not to use my lights till they are smoking hot.

Ive had my L4 for about a month now using it a little more than 1 hour a week. I also try not to use my L4 till its smoking hot. My 2 stage 22ohm Mce2s switch should be comming to me this week, I'm very excited, I originally ordered it in February but since the mail system sucks here In Iraq it got sent back. Once I have the switch on there I will be using the L4 on the lower setting more.