Led lights

[Herbertkabi]

Have used LED light few years, are common 1...2...3 watt ones.
Now I decided to try power leds, 10 ... 20 ... 50W.
First I bought three 10W LED project light from ebay.de - yeah, so-so, not bad, but also nothing distinguished. I hoped to get something good lights for my machines and for myself when some kind precision works are going on, but these 10W lamps are not as good as hoped.
Then I found from ebay.com 50W power led with driver, price was $0.98 and I did bid ...... and in the morning I saw I got it for the same money Of course for shipping was needed to pay $25 but this is very OK for me anyway. It did come from HK and received today and already tested. Also I bought few 20W LEDs from other seller ...
Yes, this 50w is very bright! but ... Im bit disappointed ... why it comes so hot?
LED I installed on to PC processor cooling radiator 80mm x 60mm x 40mm, nonetheless in five minutes it goes to 50 C degrees and it looks like in follows minutes even 60 C degrees and up ... sorry, but ... exact whet I need it - my laser thermometer batteries died up
Yes, I have read about temperature before but also I did believe this is without large cooling radiator.

Lens Color: Water Clear
Emitted Color : White
DC Forward Voltage (VF): 30~35Vdc
DC Forward Current (IF): 1500mA
Viewing Angle: 140 Degree
Color Temperature: 6000~7000K
Intensity Luminous (Iv): 3500~4000LM
Driver Quantity: 1pc
Input Voltage: AC 100V-240V 50/60Hz
Output Voltage: 30V-35V
Current: 1500mA
Operating Temperature: -20~80
Storage Temperature: -20~80

What is LED efficiency ?
My fresh experience speaks that this efficiency is not so great at all,
50W power LED comes as hot as 50W car halogen light
At that much more easy to operate with common glow lamps, and cheaper ...

Anyone has experience?
Any comments please,
cheers,
herbert

[mcphill]

You make an LED brighter by overdriving it. Overdriving it makes it hot. You should have received minimal heat sink recommendations with the part. High power LEDs ARE hot, and you must sufficiently cool them, or they will burn out very quickly. It's physics, no way around it.

[Herbertkabi]

I dont think I do overdrive this LED. I use 33V driver when permitted voltage is between 30V ... 35V. And I used very correct cooling radiator!
I hoped to get good, bright, small size and not hot, well movable, easy directable lighting for precision works.
What I see is I will get is the same hot lamp like common halogen, but there is now additionally driver box and huge radiator and ... on top of do I need to use cooling fan as well? Looks like absurdness
About physics something I do know thats because my question was about efficiency of power LEDs. Approximately 90% of the power consumed by an incandescent light bulb is emitted as heat - power LED does how?
They speak it does optical efficiency 80LM per W ... hmm... we can find out that 60W halogen makes 8LM per W ... Yes, by papers all is very nice but in reality 60W halogen gives me the same bright light and comes as hot as well but no radiators.
cheers,
herbert

[mcphill]

I didn't say you wired it wrong. The fact is, to get an LED this bright, it is "designed" to be "overdriven". When run on normal voltage, LEDs are cool. When overdriven (which is required to get a very bright light), they are VERY inefficient and run very hot.

You would be MUCH better off using 100 1 Watt LEDs, rather than 1 100 Watt LED. Probably not what you want to hear, but that is the fact with LED technology...

[Herbertkabi]

Now I understood, mcphill,
Thats good I did not buy 100W ones
Many thanks,
cheers,
herbert

[mcphill]

If you look at the second picture in your original post, you can see that the unit has 50 junctions in it, spaced in a 10 x 5 grid array. This article may help you if you are interested in some of the details:

LEDs Magazine - Fact or Fiction

[Herbertkabi]

Yeah, I thought I was yesterday bit too critical about high power leds, but after read this article LEDs Magazine - Fact or Fiction I see that theres not big difference about efficiency an incandescent light bulb or high power leds unless when used cooling fan or ... water cooling
One is clear for me - there is no way to build MINIATURE high efficient high power NOT HOT light source
Thank you very much, mcphill,
cheers,
herbert

There was cooling fan on the PC cooling radiator, I did remove ... now I will put it on to place again,
or ... perhaps I will mill a new unit - reflector and cooling radiator in one.

[Herbertkabi]

Perhaps to use Thermoelectric Peltier between Power LED and Radiator with fan ???
cheers,
herbert

[surfmachine]

Hi

I have experimented extensively with the 1, 3 ,5 and 10 watt LED's and the first thing to note is that they produce heat.
After getting over that initial disapointment / discovery, the learning then has a chance to begin.
Low wattage heat dissipation can be achieved by passive means, but as the wattage increases active cooling (fans) can be required.

What you need is a light meter to figure out what is going on.
Lighting efficiency in its crudest form is lumens per watt of power supplied.
A light meter will help you to quantify how much light is produced by a specific installation.
A light meter can be purchased on Ebay from China for around $20 AUD incl postage.

I have a wise old scientists saying that goes "you do not truely know something until you have measured it".
Guessing is always a distant second place to a good measurement.

It is not the full story however as the light itself will be produced at various wavelengths.
For this reason an incandescent flood light will seem orange/ yellow after you compare it with the white light that a cool white LED will produce.

An example for you.
The kitchen fluros are blinking and so I ponder their replacement with some 10 watt LED's.
The existing installation was 86 lumens at floor level though the diffuser and wattage as far as I can tell was 58 Watts plus an additional unknown for electrical inefficiency the the starters and capacitors.

3 x 10 Watt LED's driven by a 12 volt laptop PSU used 60 watts measured at the socket with a power meter.
The light level measured though the same diffuser the floor level was 207 lumen.
So by my calculations the light output was at least twice as much for the same power and the light quality was exceptional in terms of colour and the vision it provided.

No more excuses for burning the dinner.
These astute amongst you will also have noted that 86 lumens is not a satisfactory light level for task lighting.
Something like 250 would be considered acceptable in a workplace for such a dangerous area like food preparation.
At bench level the magic 250 lumens was available from the 3 x 10 watt LED installation.

If you doubt me about the light levels and the safety it provides just try driving at night with a torch, sure it 's A LIGHT but is it ENOUGH LIGHT !!

Surfmachine

[mcphill]

Perhaps to use Thermoelectric Peltier between Power LED and Radiator with fan ???
cheers,
herbert

Peltier would keep the LEDs cool, but you still need to cool the hot side of the Peltier. I am not sure what you are trying to achieve but if you can run a cooling block and circulate water to the hot side of the Peltier, you could be on to a "smaller/quieter" solution than just fan cooling...

[Herbertkabi]

Yes, I have bit experiences with peltiers, fan will be used of course.
I dont want to go to water cooling, perhaps sometimes this lamp will be needed in some other places and then I need to carry hoses, pump and tank and
I bought this led, yes I got it cheap, but I dont like just throw it away - now I need to do something with ... and anyway this "something" is a lamp.
Unfortunately this lamp will not be as small as hoped - there will be LED 50W 3500~4000LM... Peltier 72W... Radiator ...Fan... Led driver 1,5A... and peltier power supply 15V 6A and special driver , one more power supply because output power of this led driver is enough only for Led, not for peltier ... Im happy to have all those parts but it feels like mad-house
A little bid machinings and all this idiocy will be done - yes real idiocy
You see, my dear friends - I want to build a simplest thing - THE LAMP
But it looks like building an spacecraft
Where our world is going?
Saving some energy means in reality brutal waste,
cheers,
herbert

PS:
This 10W ready-to-use led lighter is good

[surfmachine]

Agreed, the peltier cooling solution is overly complex (as a heat sink and fan is still required), consumes excessive power and also drips condensate.
This is not a well designed energy efficient solution.
Number of commercial LED and peltier cooling solutions - none.
Just because you can does not mean you should.

The simplest solution is often the best and that remains a heat sink and a fan.
The heat sink is alloy and while initially expensive is completely reusable and recyclable.

We have very little hope of saving energy let alone the planet when design does not take the journey back to first principles, that is how many watts and how much light does the installation give.

The LED's can be glued directly to the alloy with a mixture of high temp two part epoxy and CPU thermal paste.
You will find the set time goes out to many hours but it will harden eventually.
Normally next day it is stuck fast and creates a very effective thermal bridge to the alloy.

Spend you design time on minimising the size of the fan and cooler elements and you are concentrating on the main game.
Note a fan is an important element in reducing the size of the cooler as it breaks the boundary layer of air surrounding the alloy and boosts cooling efficiency greatly over the passive thermal air currents the heat itself will naturally generate.

surfmachine