Update on LED power problem

I'm now testing a circuit with this chip and it seems to be a good fit "so far" with little additional heat.

I have been able to push these LED's past 5 amps when cooling them with water, and at 3 amps for over 24 hours.

Here is a couple of pics. The workbench in center is 12' away without flash (naturaly) and the beam angle of each LED is 170 degrees. Each LED is positioned beside the camera.

http://img.photobucket.com/albums/v124/jabam1461/LED%20test%20pics/Greenat1.jpg

http://img.photobucket.com/albums/v124/jabam1461/LED%20test%20pics/Whiteat1.jpg

Opinions?
/ubbthreads/images/graemlins/cool.gif

Can we get a little more info?
What LEDs?
What driver?
Is this the power going through the driver, or through the LED itself?

If you're driving a Luxeon *anything* at 5amps and it still works, I'll have to call BS on ya /ubbthreads/images/graemlins/twakfl.gif . The gold wire bonds used on the Luxeons are rated at 1amp, and will melt (done it, 1% duty cycle at 300KHz, ~4amp pulses) at more than 3.5amps regardless of cooling used (educated opinion).

Edit: Was remembering what current killed my green LuxIII off the top of my head. Looked in my notes and it was 4amp pulses and not 3amps as I originally had in this post.

See, this is the type of response that is non-productive and leads to flame wars.
I didnt start posting here to get into that kind of crap and wont participate in it.
The LED's we are testing for our products are NOT LUXEON! I know the product and have fidled with them for the same device's last year. This new line of diodes are going to work if we solve the power problem which appears to have been done now. We are using this chip http://www.gnuxtools.com/powerpc-sys-bom/adp3025.pdf for our supply circuit for end product. The power given is directly through the diode. The driver uses little additional current. The testing currently being done at high currents is with a bench supply with regulated current as well as voltage. The heat sink is cnc'd by us and is water cooled.
I agree with your test data for the Luxeon "fuse" result at 4 amps. Pulsing the supply does not help much either. I'm actualy surprised you got that far with it. Try cooling it better next time and you may be surprised how far you can push even them!
As for brand name... Figure it out on your own!

Did anyone win the prize?

Greg

[ QUOTE ]
lotsaluck said:
The LED's we are testing for our products are NOT LUXEON!

[/ QUOTE ]

I may come off sounding like jerk for saying this, but it is not my intent:
If you don't tell me something, I don't know it /ubbthreads/images/graemlins/icon15.gif
All your post said was "LED's" so I was left to speculate what type of LED you were driving at 5amps.

I didn't mean to start any flame wars, was just giving feedback on the information you gave me.

so can you share a little about the product you are working on?
Doc Photon

[ QUOTE ]
Rossitron said:
Can we get a little more info?
What LEDs?
What driver?
Is this the power going through the driver, or through the LED itself?

If you're driving a Luxeon *anything* at 5amps and it still works, I'll have to call BS on ya /ubbthreads/images/graemlins/twakfl.gif . The gold wire bonds used on the Luxeons are rated at 1amp, and will melt (done it, 1% duty cycle at 300KHz, ~4amp pulses) at more than 3.5amps regardless of cooling used (educated opinion).

Edit: Was remembering what current killed my green LuxIII off the top of my head. Looked in my notes and it was 4amp pulses and not 3amps as I originally had in this post.

[/ QUOTE ]


Look at Figure 3, page 2.

http://www.lumileds.com/pdfs/LED_pocket_illuminator.PDF

Go for the gusto and do 15.6A, no reason to fiddle with little boys toys:
http://www.laminaceramics.com/docs/BL_3_Red.pdf

BTW, LED arrays don't count as a LED.
http://www.laminaceramics.com/products/bl3000.aspx


I got some of these back March last year.



see also, lit up:

http://www.molalla.net/~leeper/lamina2.jpg


BTW, think those are bright, try the BL3000, they are insanely bright! Think red and amber were like 1938 lumens or so.

http://www.mouser.com/?Ntt=*lamina*&handler=data.listcategory&terms=lamina&crc=true&N=430&Ne=400

Look at the red or amber ones, labeled BL3000.

[ QUOTE ]
NewBie said:
Look at Figure 3, page 2.

http://www.lumileds.com/pdfs/LED_pocket_illuminator.PDF


[/ QUOTE ]

I was working off of that very chart when I was doing my PWM testing. I was surprised that my green LuxIII died in such a way when this doc said otherwise. But at the time (this last summmer) I was lacking funds to chance a repeat by killing another diode to find out if a soon after found hardware bug was the root cause.

I speculated that the researchers that published this document may have added extra bond wires to overcome this issue and that this graph shows the maximum current a Luxeon chip itself could handle.

Oh and I never said anything about other LED's at high currents, just luxeons...

Edit: ahh now I understand why I was misinterpited. When I said Luxeon *anything*, it's like saying any type of luxeon. Luxeon x , etc etc...

One more Edit: If you take a look at that graph again you'll see they just took the rated max current and added the "extra" current that would have been used in a 100% duty cycle into the peak current. Nothing real world here... Typical research paper /ubbthreads/images/graemlins/hahaha.gif

I've hit Luxeon emitters with 7A of current, with pulses that last only nanoseconds, for weeks. The LED efficiency goes to hell in a hen basket right quick.

If you look at Don Klipstein's site, you'll see a section where he was hammering little 20mA LEDs with 0.6 to 0.9 amps. And we are talking tiny bond wires here.
http://members.misty.com/don/ledbl.html


Rossitron:


Unfortunately, high current pulses into LEDs really kills their efficiency in a really big hurry:
http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Board=UBB6&Number=821760

And the efficiency rapidly falls apart at levels above those.

This is turning into a threadjack real quick.

I think I'm just gonna shutup now...

Ps. I wasnt looking for efficiency, I was making a fiber scanning display /ubbthreads/images/graemlins/wink.gif

I think you can pry off the dome, immerse the bare LED die and the bond wire in cold water, and push something higher through /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/crazy.gif

Hi Lotsaluck - Just curious - that building picture looks really familiar - you don't happen to be in Mountain View - do you ?

Not in Mountain View (wherever that is) and the LED is not an array. BTW what kind of $'s did you burn up with the array's?
These LED's cost us $15.00 each.
Yes there is a winner (so far) and as long as the test supply holds out another 24 hours the led will be sent. We are in email contact.
/ubbthreads/images/graemlins/grin.gif

BTW guys the LED's can be found here.
http://www.globalsources.com/gsol/I/LED-manufacturers/b/2000000003844/3000000157524/11650/1.htm

Water Cooling

How do you manage the water cooling?

Re: Water Cooling

Now that I can talk about as we have that pat. issued.

The LED is mounted on an aluminum heat sink similar to the Luxeon's. We designed a heat sink that is in two parts and bolts together in the middle to form one. At this intersection we have milled in mirror image capilaries into each side of it so when the two come together it forms a vien similar to a blood vessel. Nothing to special here yet, but the real neat part is the way the thermal management works to circulate the water without any moving parts. Nature decided heat would rise so we used that in the way of design to move the liquid without pumps. Send the liquid to a small heat exchanger and we have a very high output LED in a very small package at the light itself. With better equipment the whole thing could be tiny, but ours was enough to prove the function.

Re: Water Cooling

Why did you decide not to utilize heatpipes for cooling the LED via the extremely fast vapor phase change mechanism, because others have already done it?

Heatpipes also use no external power either, and most also utilize water. You could even turn many flashlight heads into a heatpipe themselves, reaching thermal conductivities that are up to 2000 times lower than copper.

Re: Water Cooling

The main concern here was size constraints and keeping the thing in the 1.25" cube. Also the system we are useing is a much better fit into the environment that most of the designs are made to be used in.

Re: Water Cooling

Have you made provisions for the expansion of water when it turns to ice? Doesn't take long up north for things to freeze in the cold.

A heatpipe can be made to take many forms and shapes, and can even be a sphere or whatever. Heatpipes are mostly air, so what ever liquid that turns to ice has somewhere to expand to.

Re: Water Cooling

Have not, and won't as these device's will never be used in freezing water conditions as a pre-req of their primary use. If the environment they are to be used in is freezing then the user has MUCH bigger problems... LOL