About Efficent LED's for DanF

[LeissKG]

Hello Dan

On the otherpower.com page

"Designing a tiny and cheap solar power system for a pop-up camping trailer"

you state that LED lamps are not very efficient. The same is more or less stated on the page "Efficient Lighting" on otherpower.com. I want to update you on this, efficient LED lamps are available, but not necessarily cheap.

See

http://www.leds.de/product_info.php?info=p211_HighPower-3-Watt-LED-Spot-MR16-white--12V.html

12V / 3 W seems to give ~ 80lm/W. The Voltage and the recommended current give another value ~ 50 lm/W. I don't know what is right for this lamp but both values are pretty good.

Looking at single LED's you get some better values

http://www.leds.de/product_info.php?info=p266_Seoul-Z-Power-LED-P4-star--white--240-lumen.html

Here you have the following efficiency

119lm / (0,35A x 3,2V) = 119lm / 1,12W = 106 lm/W

or

240lm / (1,00A x 3,8V) = 240lm / 3,80W =  63 lm/W

Klaus Leiss

[richhagen]

I've been experimenting with some mr-16 bulbs made with 3 Cree 80 lumen led's.  So far so good.  I think they will soon be able to give compact flourescents a run for their money.  Cree is currently vending commercial LED's with up to 100 Lumens per Watt although they have produced and tested samples at over 130 Lumens per Watt through NIST.  I don't know about the noise levels from the switching power supplies that will be required to reduce the voltage for the LED's though. . .   Rich





This is the MR16 bulb, it is 12V and is made for track lighting systems.  This one is a wide angle bulb.  Basically there are no optics to focus the Cree LED's output.

The leds are mounted on a pc board that is basically laminated aluminum.  The aluminum conducts heat away to the metal housing rather efficiently.  There is also a small circuit with a full bridge rectifier which allows for use on 12V AC or DC circuits.





I measured .23 Amps at 12.94 volts across this one for 2.98 Watts of consumption.  I have no way to accurately measure the light output, but it is very bright in comparison to the light made from 5mm leds on the edge of the right side of the picture which is drawing .42 amps at the same voltage.  It definately appears to give me my 3 Watts worth.  

My hope is that in the long run they may give us fewer reliability issues than the small flourescents for missions such as the one I participated in with BTHumble to Fiji:  http://www.fieldlines.com/story/2007/6/5/85322/76409

[Nando]

Rich:

the large LEDs are still too expensive, I am at the present evaluating and design them for use in airplane internal lighting.

The BOEING 787 to be shown tomorrow Sunday is lighted all the interior with LEDs, for reading and for ambient with capabilities to be light level adjustable and as well every module has to have AUTO SELF testing and failure report to the main computer in the plane, for it to communicate via satellite to the on course landing site for immediate module replacement without any airplane delaying replacement time

In addition the light beam has somewhat narrow dispersion cone, requiring additional optical parts to do the proper light coverage.

The low volume price is too high for some alternative energy systems and it would be better to have the small 10 mm size in multiple use to cover a better lighted area.

For the light output versus watts, still the small fluorescent lamps outshine the LEDs, this based on large lighted areas like a room.

23. 0r so Euros for a 5 watts in a reflector is too expensive, I think.
    
12. volts input but no indication of a pwm controller current source.
    
    

Nando

[DamonHD]

Hi,

As an experiment I bought the 5W (mains voltage) one of these.

Very expensive and the light colour is not great: washed out daylight.

See first image on http://www.earth.org.uk/LED-lighting.html

LEDs are just starting to pass CFLs in efficiency (lumen/W) for, for example, daylight colour, but have a way to go on some other fronts.

I'm going to keep trying though!

Rgds

Damon

[LeissKG]

Nando wrote:

"In addition the light beam has somewhat narrow dispersion cone, requiring additional optical parts to do the proper light coverage."

I don't understand that. Almost all high power LEDs have an half intensy angle of 120 Degrees without any optics. That is more than most other spots do. So if you want to replace a spot you would need additional optics to get a smaller cone.

Klaus Leiss

[ADMIN]

Thanks Klaus, and all -- LED efficiency is certainly starting to push the point where they are near CFs. The next step is when commercial LED fixture builders start using the new LEDs.....that's the hold-up now. Home experimentors can make some pretty efficient LED fixture now, but the normal folks who want to buy them for campers and RVs and such are still seeing last year's high tech stuff, or earlier. Bring 'em on....

DAN F (admin)

[etownlax]

Well I was at Lowes the other day and something caught my eye.

It was a 3 Watt LED module for a large "police-type" flash light. It was just a regular looking bulb but you could see the little LED chip on it. And the plastic packet said "3 Watts!" It was 19.97 for any one of them. They have them for 2(3v), 3(4.5v), and 4(6v) cell flashlights.

So those might be real easy ways for lighting. Though if you used 2(6 watts)LED's that would give PLENTY of light BUT for 40 bucks! Is that really worth it?

-Randy

http://www.lowes.com/lowes/lkn?action=productDetail&productId=244302-76859-IH32DCW6J&lpage=n
one

http://www.lowes.com/lowes/lkn?action=productDetail&productId=244306-76859-IH33DCW6J&lpage=n
one

http://www.lowes.com/lowes/lkn?action=productDetail&productId=244308-76859-IH34DCW6J&lpage=n
one