# Experience with 8mm 1Watt LEDs



## Nate (May 12, 2011)

I've done a bit of digging & cant find much on here or anywhere else...

Does anyone have much experience with running this style of LEDs?
Ebay specials (specs are of course suspect from the beginning)
Supposed Specs:
- Strawhat 140deg angle
- 8mm
- 180,000-200,000mcd
- 300mA

I know its all about heat management with LEDs etc.. so i'm after some guidance if anyone has actually used them.

Looking at hooking them up as bike blinkers, so 50/50 on/off with infrequent use which would allow for cooling in between usage.
However as there's no sinking, I think it could still get up to high peak temps which would decrease the lifetime.

I'm assuming they've just thrown a 1watt die (if thats the term?) into a crappy little 8mm package - and just quote the specs of the die?

i'll of course be doing some extended testing when i get them in & report on the results!
planning on both continual flashing use & something more resembling cycling - i.e 3 x 7sec periods every 5min or something like that.

Flashing rate (left LED)


----------



## JohnR66 (May 12, 2011)

I knew before I opened this thread the word "eBay" was going to in it. I can't speak specifically about these LEDs but the ones I've tried were the worst junk I have ever laid my hands on. Even at underdrive the things lost all of their brightness after a few days of operation.

There are companies like DigiKey, Mouser and the like who would be happy to sell you a quality part.


----------



## Nate (May 12, 2011)

What were the specs of the ones you used?
How hard did you drive them? constant?

I'll see how they hold up - otherwise i can get some Osram yellows: LYW57B-FYGY-26-Z for about $2 each
i'll have to go down the path of a "proper" emitter on a small star & seal it appropriately.

Ledsales.com.au have a 0.5Watt white 8mm - so something similar, not sure how "legit" the claims are but they'd have to be one up from ebay at worst.


----------



## Lynx_Arc (May 13, 2011)

If they don't have a pad on the bottom and instead have 2 legs in a clear plastic case they won't take 1 watt for long because they cannot get rid of the excess heat generated at that power level through the leads burning up over a short time. My advice is to use decent quality 5mm LEDs for what they can do and go with the high power LEDs that mount on heat sinks for beyond that and skip the 8/10mm plastic bodies with 2 leads sticking out as no decent company makes those I know of now.


----------



## Nate (May 13, 2011)

Lynx_Arc said:


> ...


 
No offence intended - I'm aware of the power/heat sinking etc - hence my very specific question about experience with them.
I know the "best" (most reliable) option is a "proper" emitter & sink - but in my specific application (lower duty cycle) is it possible.

Hopefully i'll have them next week & can post up some testing results


----------



## Lynx_Arc (May 13, 2011)

Nate said:


> No offence intended - I'm aware of the power/heat sinking etc - hence my very specific question about experience with them.
> I know the "best" (most reliable) option is a "proper" emitter & sink - but in my specific application (lower duty cycle) is it possible.
> 
> Hopefully i'll have them next week & can post up some testing results


 
I'm not offended, good luck with your LEDs. You should look up JohnR66's reviews on the forum as he has done quite a few on many LEDs. I have read reviews on all sorts of non high end LEDs and tinkered with them and to be honest anytime a chinese company (especially ebay) says 1 watt LED it is meaningless to me. I bought a light that was supposed to be a 3 watt LED and the LED fried using a boost circuit off 2AAAs that drove it at 80ma. It was a 5mm LED with a larger than normal die in it. Took about 4 days to start strobing bad on me. I replaced it with a cree 5mm and so far it works fine.


----------



## Nate (May 13, 2011)

yeah trying to get something close-ish to the output of the Radbot 1000.
I just opened it up & no heatsink on it - is it a Nichia? (think i read it somewhere) Driven at 0.16watt?

Best option might be a Lumiled - 70mA, 600mcd, 70deg angle @ 80cents
Cheaper than the ebay ones!


----------



## JohnR66 (May 13, 2011)

I tested a few different 8 and 10mm .5 watt white LEDs from some ebay sellers. They were multidie LEDs. At .5 watt, the current would be around 140 ma. From memory I drove them much lower, say about 100ma and they nearly went dark in a week. The test I performed was two or three years ago. I have no evidence to show if these things are improving or not, but at 1 watt claim. I'm not getting my hopes up. I'm not looking back to that crap because there are far better products by good manufacturers. If you going to do it, might as well do it right.


----------



## Lynx_Arc (May 13, 2011)

JohnR66 said:


> I tested a few different 8 and 10mm .5 watt white LEDs from some ebay sellers. They were multidie LEDs. At .5 watt, the current would be around 140 ma. From memory I drove them much lower, say about 100ma and they nearly went dark in a week. The test I performed was two or three years ago. I have no evidence to show if these things are improving or not, but at 1 watt claim. I'm not getting my hopes up. I'm not looking back to that crap because there are far better products by good manufacturers. If you going to do it, might as well do it right.


 If it blinks around 60-80ma a quality 5mm LED would probably withstand that duty cycle. Have you tried removing one lead of the LED and testing the drive current to it to get an idea?


----------



## Nate (May 17, 2011)

LEDs finally arrived...
They're pretty beefy & solid looking in terms of heat sinking - well as much as you can in that package!
I'll post up some pics & do some testing tonight & see how the little guys run.


----------



## Nate (May 18, 2011)

So far so good... pumping 250mA through them & no issues, barely any heat at all!
the 2 x 1/2Watt resistors in parallel i'm using however - ouchies! pumping 1.4Watt though them though
Seems they might be pretty damn good!

Update - running them at 250mA for about 5min - they're warm!
The plastic itself is relatively cool, however the "heatsink" leg is at 77deg (according to my DMM temp probe).

Still sucking 250mA from a single 18650 cell, i'll let it run for 15min then compare to another LED to see how much its lost.
Then ill do an extended burn in test in flashing mode


----------



## Nate (May 18, 2011)

After 1.5hrs at 250mA - its still looking ok.
Comparing to another LED in the package, it looks a little more reddish & slightly dimmer.

Its not a pass with flying colours, but i'd still call it a pass - given the constraints of the package its in.
i'll do a long duration flashing test & see how it holds up, but so far i'd give it a pass.


----------



## Lynx_Arc (May 18, 2011)

you have to remember that plastic is an insulator when it comes to heat so heat that isn't wicked off through the legs builds up slowly so trying to judge how hot the die is may be harder than you think. I would say if you had enough extra LEDs just take two of them at the same current levels and compare them.. if they are equal run one for a week continuously and then compare the output of them both again and see if you can discern any dimming. I would say then that blinking them would increase runtime considerably more. It could be possible that the 250ma is a max input level (short burst, blink) and the continuous output level is around 150ma.


----------



## Nate (May 19, 2011)

yeah exactly - i was considering removing some plastic to expose more leg for sinking, but in my application - they're going to be great without it.

I doubt they're 200,000mcd or 1Watt, but for a blinking application with 250mA - perfect.
If i went down the "proper" path with a red cree - heatsink, lens & i'd have to protect it from all the road grime etc - these are already sealed so perfect.
pretty happy!


----------



## Lynx_Arc (May 19, 2011)

I would guess they may be souped up half watters perhaps 4 dies. One way to tell if they are is with a magnifying lens on the output at the right distance. If they are indeed half watt they may take up to 150ma continuous for perhaps a few thousand hours and depending on the blink rate and duration 250 watts could easily be handled if the power listed was maximum (not continuous). I have seen many LEDs that list maximums a lot higher than recommended or nominal. Some 5mm LEDs list maximum at 80ma


----------

