# Cheap LEDs getting worse



## JohnR66 (Jul 14, 2011)

I haven't bought any LEDs off ebay for about three years after "fade" testing and finding their lifetimes to be very short. I decided to try some again to see if there is any improvement. I bought some 27,000mcd white 5mm LEDs from one prominent seller. I noticed that the 55,000mcd claims have stopped, so perhaps there is more truth to the specs. Okay, Here's what I found.

On my light meter, the LED output 9,000mcd @20ma. Well, that's 1/3 of the rated output.:thumbsdow
Like most of them before, these had the bluish white light.:thumbsdow
At 30ma continuous current, the LED was tested for 60 hours (whopping 2.5 days). I checked it again afterward and found light output was at 3,600mcd or 40% of initial output. It probably dropped below 70% after 1.5 days.:thumbsdow

This sets the bar higher for complete utter garbage.


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## richpalm (Jul 14, 2011)

I quit Ebay for everything-seems it's all greed, shipping ripoffs and scumbags. 

Rich


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## jtr1962 (Jul 14, 2011)

I only buy name brand LEDs like Osram or Nichia off eBay these days. The rest of the stuff generally isn't even worth looking at.


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## Helmut.G (Jul 15, 2011)

Actually most 5mm LEDs will have a short life-span at 30mA, the current is too high for them, they heat up and die.
I agree that you shouldn't buy no-name stuff from ebay unless you want to be ripped off.


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## HooNz (Jul 15, 2011)

OP , thanks for the info , i have yet to see a 'white' 5mm that has no blue , even a very small amount or not noticeable .

But i probably see all the cheap stuff.


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## bshanahan14rulz (Jul 15, 2011)

We got some old computers that had 3mm white indicator lights. That was the purest white light I'd ever seen from a standard encapsulated LED. I was very surprised, but then again, these computers were made by Sun.


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## JohnR66 (Jul 17, 2011)

Helmut.G said:


> Actually most 5mm LEDs will have a short life-span at 30mA, the current is too high for them, they heat up and die.
> I agree that you shouldn't buy no-name stuff from ebay unless you want to be ripped off.



I tested the Cree C503C series and Nichia GS LEDs at 30ma and they lasted 4,800 hours until 70% of initial intensity. The Radio Shack 276-017 is almost at two years and still at over 90%. So, good 5mm LEDs will last long.

Running the LED at half this current can more than quadruple its life. I tested some cheap LEDs at 12.5 ma and they last around 300 hours which is not even two weeks. Junk is junk. Low current won't make them last as long as they should.


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## MikeAusC (Jul 17, 2011)

The only significant heatsinking for a 5mm LED is through the wires.

If it's not mounted on PC Board with short leads to a reasonable area of copper, the die will run very hot.


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## Helmut.G (Jul 18, 2011)

JohnR66 said:


> I tested the Cree C503C series and Nichia GS LEDs at 30ma and they lasted 4,800 hours until 70% of initial intensity. The Radio Shack 276-017 is almost at two years and still at over 90%. So, good 5mm LEDs will last long.
> 
> Running the LED at half this current can more than quadruple its life. I tested some cheap LEDs at 12.5 ma and they last around 300 hours which is not even two weeks. Junk is junk. Low current won't make them last as long as they should.


so what are the claimed numbers for the cree and the nichia? 4800 compared to the 50000 hours many manufacturers claim would be a huge reduction. the radioshack sounds real good:thumbsup:
sure junk is junk, I was talking about the good ones when I said they don't live long at 30 mA.


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## JohnR66 (Jul 18, 2011)

I'm not aware of life time claims for those LEDs. Nichia claims that none out of so many failed after 1000 hours, but that is their general stress test and not a real life time test. Many power LEDs life time ratings are not given at max current either. As I recall, the max current of the Cree XR-E was 1000ma and 50K life was rated at 700ma.

If operated at 20 ma, the Cree and Nichia 5mm LEDs could last to 50k hours. It depends on how over the edge they are pushed at 30ma. For example, A LED I tested lasted about 250 hours at 39ma. Driving the same part number LED at 30ma increased its life to 3,500hr. The lower current LED had 14x the life.

Who knows what the limit is on the cheap junk. If 12ma is still too much, perhaps 8ma is safe.


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## Lynx_Arc (Jul 18, 2011)

the problem with running LEDs at lower currents is if you don't invest in a regulated driver for them then you have a lot less range of operation vs a 20ma to dim nothing you have an 8ma to dim nothing with 3 times the LEDs to make up for the light output. Trying to match tint and Vf of a handful of cheap 5mm LEDs is a pain you tend to end up with a few that are dimmer than others at normal Vf and at low currents they go almost out. I have several multiple 5mm LED lights including xnovas and shower head 20+ led models that when the batteries are mostly depleted about 1/10 the LEDs look burnt out but rather just have higher Vf and won't light up. Many 5mm based lights overdrive the LED at the start from fresh alkaline and if you use lithium primaries the overdrive can be worse.


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## Helmut.G (Jul 19, 2011)

JohnR66 said:


> If operated at 20 ma, the Cree and Nichia 5mm LEDs could last to 50k hours. It depends on how over the edge they are pushed at 30ma. For example, A LED I tested lasted about 250 hours at 39ma. Driving the same part number LED at 30ma increased its life to 3,500hr. The lower current LED had 14x the life.


you're right, I'm sure the LEDs sold by brands like Cree and Nichia are not overrated, they will reach their rated life driven at 20 mA.
But even a seemingly small overdrive will very heavily reduce the life of any 5mm LED if you don't attach some kind of heat sink, that's my point.


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## 2009Prius (Jul 19, 2011)

Haven't been here for a long time and glad to see John is still around doing good work. Thanks for the update!


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## Lynx_Arc (Jul 19, 2011)

not much of a way you can heatsink a 5mm LED well as the tiny metal leads don't allow for much heat flow.


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## MikeAusC (Jul 19, 2011)

Lynx_Arc said:


> not much of a way you can heatsink a 5mm LED well as the tiny metal leads don't allow for much heat flow.



. . . I can only try to help.


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## Lynx_Arc (Jul 19, 2011)

MikeAusC said:


> . . . I can only try to help.


 
I don't think it helps a lot to heatsink, probably helps more to lower the drive current (underdrive). A shower head LED with 32 5mms takes awhile to heat up so there is some heatsinking but I wonder if it is as much the trapped air surrounding the plastic case than the leads.


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## Helmut.G (Jul 20, 2011)

In a showerhead-style flashlight heatsinking might be difficult but if you only have single LEDs with a bit of airflow, soldering a bit of metal to the leads as a heatsink will help. Some guy in a german LED forum uses small coils made of thick copper wire from old powerlines and he claims this lowers the temperature significantly.


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## Lynx_Arc (Jul 20, 2011)

From what I have seen lately, most times 5mm LEDs are used they are in arrays like showerheads so heatsinking is by circuit boards and proximity to other LEDs limit air cooling. I am not sure what cree 5mm LEDs cost but nichias can be too expensive for large arrays such that you are better going to high power crees or rebel LEDs. I was playing with a shower head LED light last night that put out decent light at low current levels so it probably is better if you have the room to underdrive cheap LEDs and add more of them into the mix. Instead of 1 nichia or cree use 4 or more cheaper LEDs at 5ma current if they can hold up at that level they are cheap enough but the hassle of dealing with multiple LEDs is not worth it most of the time as you get unmatched from the same batch the cheaper they are. I have shower head lights that have 3 or more different tints of LEDs in them at low levels it looks rather ugly


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## JohnR66 (Jul 20, 2011)

I'm surprised at how much heat comes down the die cup lead. Some arrays I made warm up pretty quick on the solder side of the board. Of course they are 100mw devices and aren't designed with much thermal dissipation in mind. Packing them together and driving them hard will make a lot of heat and shortened life. They work best with some "breathing" room and mounted down on the board for shortest thermal path. If more than 5 or so are needed in a fashlight, it is better to move to medium power LEDs. Not the junk on ebay either. Some of those .5 watt LEDs were the worst. .5 watt is around 140ma. I had some nearly go out with a dark spot over the die in a week at only 100ma. They were multi chip with a heavy brass leadframe.


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## Lynx_Arc (Jul 20, 2011)

I often wonder why they don't extend the die cup outside of the plastic and use it for direct heatsinking instead of sealing it in.


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## Helmut.G (Jul 21, 2011)

Lynx_Arc said:


> I often wonder why they don't extend the die cup outside of the plastic and use it for direct heatsinking instead of sealing it in.


that would make sense for the 0.5Watt units and similar, but as long as most customers don't know that heatsinking is crucial, they probably don't do it to save money.


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## JohnR66 (Jul 21, 2011)

Lynx_Arc said:


> I often wonder why they don't extend the die cup outside of the plastic and use it for direct heatsinking instead of sealing it in.



For a quality product, it isn't necessary. A lot of people here like to push LEDs well beyond their datasheet limits. 5mm LEDs were designed years ago to be indicator lights and the epoxy encapsulation was the ideal cheap solution. The datasheet values, when not exceeded, will provide thousands of hours of use when a quality part is spec'ed. If the LED is to be pushed, another solution is needed. That's why there are surface mount packages with a better thermal path available. The Cree XP-E/G series LED packages are smaller than the 5mm LED!

Of course the 5mm indicator package is super easy to use for the weekend hobbyist with its integral lens and simple to solder leads. Perhaps the metal can design would provide a better opportunity for heat sinking. (pic on right) But is likely to cost more. The industry has gone surface mount for most things anyway.


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## bshanahan14rulz (Jul 21, 2011)

I've seen some cheap makers simply increase the mass of the cupped electrode. Still the same lead width, though the wider portion extended all the way down to the insertion stops on the leads.


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## Lynx_Arc (Jul 21, 2011)

I wonder if cree or nichia will upgrade their 5mm LEDs to keep up with the latest crees in the future? Imagine if they get a handle on the heat the output of a 5mm LED could actually approach the old luxeon 1 and 3 LEDs one day.


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## Lynx_Arc (Jul 21, 2011)

bshanahan14rulz said:


> I've seen some cheap makers simply increase the mass of the cupped electrode. Still the same lead width, though the wider portion extended all the way down to the insertion stops on the leads.


 
I have one of these LEDs... it was in a 3watt mxdl 2AAA light and overdriven at 80ma which made it strobe and burn out. Luckily I bought the light only for the boost circuit it was a $3 chinese light. I don't see how you could get more than maybe 5% more light out of it with a larger cup as there isn't any better thermal path to speak of.


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## JohnR66 (Jul 21, 2011)

Lynx_Arc said:


> I wonder if cree or nichia will upgrade their 5mm LEDs to keep up with the latest crees in the future? Imagine if they get a handle on the heat the output of a 5mm LED could actually approach the old luxeon 1 and 3 LEDs one day.


 
Good question. Yes they are! Check out the new Nichia GS 28 lumen (!) 80ma 5mm LED.
http://www.nichia.co.jp/en/product/led.html?op=cond=type='NSDW570GS-K1'

I noticed Cree's color 5mm leds prices have dropped by about half and the intensity figures are much higher from when I ordered them a year ago. I noticed this at DigiKey, so I ordered some and they are on their way to me now. I will post something if they are brighter than previous ones I reviewed here last year. The prices/intensity of the white ones haven't changed yet.

I see Nichia has introduced a set of oval LEDs to compete squarely with Crees Screenmaster series. Nichia also has a new high efficient 350ma LED that looks similar to the XP-C/E/G series of Cree leds.


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## Lynx_Arc (Jul 21, 2011)

70ma for a 5mm LED? that is something for sure. if they can get 28 lumens that would make for another ball game but if the cost is related nichias are IMO ugly looking light for the money. I would rather have an 18 lumen nice beam and tint 5mm LED than a brighter blotchy purple bluiesh mish mash LED costing over $1 each


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## deadrx7conv (Jul 21, 2011)

That 28lm Nichia would be the ultimate keychain or Solitaire upgrade! 

The efficiency is almost up there with the better LEDs like XML or XPG. Cree needs to chop up an XPG or XML into 5-8 pieces and make some 5mm LEDs that can take 70-80ma!

http://www.cree.com/products/pdf/LEDlamps/C503D-WAN.pdf


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## Lynx_Arc (Jul 21, 2011)

deadrx7conv said:


> That 28lm Nichia would be the ultimate keychain or Solitaire upgrade!
> 
> The efficiency is almost up there with the better LEDs like XML or XPG. Cree needs to chop up an XPG or XML into 5-8 pieces and make some 5mm LEDs that can take 70-80ma!
> 
> http://www.cree.com/products/pdf/LEDlamps/C503D-WAN.pdf


 
all they would have to do is have an underdriven cree xp series LED with leads on it instead of surface mounting it.


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## Lynx_Arc (Jul 21, 2011)

As long as they get rid of the lousy half watt LEDs.. I have a few lights with them and hate them more than 5mm LEDs as mostly they have a tiny hotspot that is useless and annoying or they have a blotchy hotspot from several dies that are not the same tint/output.


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## pavithra_uk (Jul 24, 2011)

these all chinese poop. I brought that kind LEDs from many sellers (not ebay. local sellers.) all LEDs reduce light output/died/flicker after few months.

even they running at 17~19mA, they failed. 

in here Sri lanka, cost per 1 5mm white LED is 0.05$ ++. but not cheap to us. 

Good LEDs like Cree, still very rare in here. finally I found local seller who selling 3W Luxeon LEDs for 1$ per unit without star shaped heat sink. I got 5 LEDs. what a poop sellers are they.. they brought quality check failed lot of LEDs. 2 LEDs are warm white. 1 is cool white & 1 is nutral white. 1 not working.


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## bshanahan14rulz (Jul 25, 2011)

All of my 5mm "5-chip" LEDs are still running, although not as bright. Not that I use them that often, they are on cabin light duty in my car, in a (5p)3s6p array, each series limited with a resistor to drive at 100mA, powered off a 12V regulator with PWM modulation. The tints haven't shifted from their random assortment of white, blue-white, green-white, and pink-white varieties. I keep telling myself to redo it....


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