View Full Version : Led lights

03-30-2011, 03:43 PM
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 ...:rolleyes:... and in the morning I saw I got it for the same money :cool: 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! :eek: 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 :mad:
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,

03-30-2011, 04:11 PM
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.

03-30-2011, 05:01 PM
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 :o 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.

03-30-2011, 05:34 PM
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...

03-30-2011, 05:44 PM
Now I understood, mcphill,
Thats good I did not buy 100W ones :o
Many thanks,

03-30-2011, 06:33 PM
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 (http://www.ledsmagazine.com/features/2/5/8/1)

03-31-2011, 03:29 AM
Yeah, I thought I was yesterday bit too critical about high power leds, but after read this article LEDs Magazine - Fact or Fiction (http://www.ledsmagazine.com/features/2/5/8/1) I see that theres not big difference about efficiency an incandescent light bulb or high power leds unless when used cooling fan :o or ... water cooling :mad:
One is clear for me - there is no way to build MINIATURE high efficient high power NOT HOT light source :rolleyes:
Thank you very much, mcphill,

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.

03-31-2011, 05:32 AM
Perhaps to use Thermoelectric Peltier between Power LED and Radiator with fan ???

03-31-2011, 07:58 AM

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 !!


03-31-2011, 09:23 AM
Perhaps to use Thermoelectric Peltier between Power LED and Radiator with fan ???

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...

03-31-2011, 03:17 PM
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 :cool: but it feels like mad-house :tired:
A little bid machinings and all this idiocy will be done - yes real idiocy :mad:
You see, my dear friends - I want to build a simplest thing - THE LAMP :o
But it looks like building an spacecraft :eek:
Where our world is going?
Saving some energy means in reality brutal waste,

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

03-31-2011, 09:40 PM
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.


03-31-2011, 10:20 PM
Just noticed the original test platform - no fan.

Most high power CPU's have a thermal design property of around 95 + watts.
If you were to run the CPU flat out using a application like "toast" and monitor it with another app like "speedfan" you will see how the temp builds in real time.

Consider the CPU the same as your LED, a heat source.
Run the CPU flat out with the fan and then without the fan and you will see the rapid and concerning temp increase in the second scenario.
My experience here comes from passive cooling experiments in PC's here but is directly relevant to your interest in LED's.
The inference is of course that with a typical 95 - 125 watt CPU cooling fan and heatsink you should be able to effectively cool your 50 Watt LED.

As a design criterion 50 degrees C is fine. Electronics can run hotter but service life falls away after this point.
So that is your engineering challenge to get the size of the cooler you want at the temp you are prepared to run at.

Good luck and enjoy the journey.


05-03-2011, 07:10 AM
Waked up early in the morning today and finally started some quick machinings ... took couple of hours and now - here it is - 50W LED lighter with integrated cooler and integrated power supply.
OD 69mm, L-205mm, there is 33V LED-driver inside - thats because its so long, as well as PC cooler and small DC/DC converter for. End cap on the back I will mill out later ... too bored today :(
Yeah - now it really does not go hot - forepart ca 35C degrees.
I bought special 62mm reflector and lens exact for this LED, via eBay from Taiwan.
Yes, it is bright ... even very bright, but is it better than 50W...60W Halogen or Xenon bulbs? Im not sure. At least there you do not need the cooler and extra driver ... and costs much less.
Looks like I built the most stupid lighter in the world :o
I have one 30W and few 20W LED but I dont want to build such kind monstrum anymore :rolleyes:

05-03-2011, 10:50 AM
Beautiful craftsmanship on LED light.. Really love the simplicity.

05-03-2011, 02:57 PM
Yeah, now the end cap is also done,
Lamp has got a little bid scratched but ... :o ... perhaps sometime later will finish,
At first I need to find where to use such kind of swooshing lighter :(

For milling machine I need to bethink something smaller, lighter, better,
I hope to use or 20W or 30W LED without radiator and no fan :rolleyes:

06-29-2011, 05:58 AM
Hi Herbertkabi,

We made this adjustable lamp using 3 Cree LED’s and optical lenses for a machine tool lamp and it’s super bright. We only run the LED’s 300 m A.
See picture of our DRL’s light output at About Us (http://www.celgo.co.za) it’s 4x 1w Cree LED,s with spot light lenses.

06-29-2011, 09:59 AM
Yeah, nice lamps,
Why I do not see how/where to buy and what is cost of :o

In fact my 50W led lamp is inasmuch bright that no way to use as machine tool light if you do not like to wear a sunglasses :(
the only advisable use is photography or cinematography
Still have 30 watt and 20w ones, will build when sure purpose comes up.
One 20W LED is red - what the hell I need to do with, who has any idea :idea:

06-29-2011, 01:50 PM
If you have a way to do pulse width modulation, you can dim the 50W to whatever you want. You just need to turn if off-on-off-on-... very fast (with a controller). Vary the duration of the on and off times and you can make it as dim as you want, up to full bright.

06-30-2011, 02:25 AM
If you have a way to do pulse width modulation, you can dim the 50W to whatever you want. You just need to turn if off-on-off-on-... very fast (with a controller). Vary the duration of the on and off times and you can make it as dim as you want, up to full bright.

Thank you very much,
I know what is PWM, but how I can to do like that when I have factory made "current sense" 33V power supply especially for this 50W LED :confused:
Perhaps this is just common switch mode ac/dc 33V powers supply, nothing about specific "current senses" inside?
To be honest my 30W and 20W LEDs I have tried with common regulated power supply ... works very well :rolleyes: but I was little bid be afraid I will ruin these LEDs :o but now when to think about and to look at cost of power supplies then ... "special" power supply for LEDs costs twice more than the same parameter common switch mode power supply ... "special" is just business trick?

06-30-2011, 05:02 AM
Hi Herbert,

That machine tool light is a one off I made up from components of our other lights. I am using it on one of my own machines. I was thinking of making it with a magnetic base and rechargeable batteries, a type of mobile machine light. Still deciding on that.


07-10-2011, 02:55 PM
I wanted to build a super bright light that I could use for building models but I never thought about the heat generated by fifty or one hundred LED's. Needing all the cooling stuff sort of defeats the idea of building a super bright LED lamp. Besides I don't know enough about electronics to monkey with it anyways.