is the led the most bright per watt?

is the led the most brightess per watt?.also id love a easy to read faq on led benifits and etc etc

I believe that at least for a while, the LED might have been the winner under 5W's. Above that, CCFL and Halogen I think have higher effacacy (sp). Now with some of the latest small fluorescent products, they may be encroaching in the under 5W category as well. I am sure someone who knows the current standings will pipe in here soon.

- Don

Actually, it's about a push. 20 or so Lumens per watt. As Don suggests the scales swing back and forth with levels, but past a few watts halogen lights beat LEDs, and floursecent lights really clean up. An interesting web site to just this topic is

"Are LEDs more efficient?"

Other interesting LED stuff from the same guy (as well as lots of keen links, including the requested FA) can be found at

Don's LED page

Cheers.

Doug Owen

McGizmo: Did you mean to say efficiency? /ubbthreads/images/graemlins/grin.gif. Efficacy was a term we used in [high school] debate a lot, but it doesn't have to do with the word efficient. Rather it means the ability to put something into action or the ability to produce a desired effect. For example, a common argument would be "I don't have to prove efficacy, only that [the argument] works (or should be applied) in the realm of philosophical or moral theory".

Nothing beats the efficiency of bioluminescence-- it's almost 100%. Heck, it grows on trees too (via fungus) In terms of products you can actually use, though, LEDs and good bulbs are about the same in flashlights. My L4 has about the same lumens/runtime as a E2E. In very small applications, though, I think LEDs are more effecient but can't quantify this. Larger than 5W or so, a flourescent, halogen, and other exotic bulb types are more efficient.

Don Klipstein is "The Man". /ubbthreads/images/graemlins/thumbsup.gif One can lose oneself for days prowling around his web site. But folks, aren't we forgeting HIDs here (if we don't limit ourselves to 5w)?

Dan

http://lighting.sandia.gov/Xsslatsnl.htm

'Sandia has authored or co-authored a number of white papers and general articles which explore the technical challenges associated with solid-state lighting, and the potential impact of solid-state lighting on energy consumption. A few of these are:

"Another Semiconductor Revolution: This Time It's Lighting" (pdf file)'

http://lighting.sandia.gov/lightingdocs/HaitzR200003.pdf

Hawkhkg11,

The word I was after was efficacy. It is mentioned in Doug's link cited above. And hey, for me, I was dang close in spelling this time! /ubbthreads/images/graemlins/tongue.gif

- Don

i have all floerscent in my house the kind you put in a bulb socket.

Re: is the led the most bright per watt?

It's true that LEDs and halogens have approximately the same lumens per watt when the halogens are being driven at spec. But with a battery powered device, you can't always assume the light is being driven at spec. As the battery dies, the voltage drops and halogen efficiency drops off dramatically while the efficiency of an LED may actually rise. To me, one of the most endearing qualities of LEDs is that I can take a battery that won't generate any light at all in a conventional flashlight and use it to produce light in a LED flashlight. Obviously, when the battery is near death, the LED is putting out a lot more lumens per watt than the halogen.

Re: is the led the most bright per watt?

so i guess the benfit to led is it can run at more wide range of specs but over halogen its main benifit.is that they dont burn out?

Re: is the led the most bright per watt?

Dependability, durability, longevity and specific color are all features of LED's which give them an edge in many applications.

- Don

Actually the HID's clean upon the fluoro's. It is hard to find Fluorescents better then about 70 lumers/watt, and 100 lumen per watt HID's are common (The D2S used in automotive headlights is about 90 lumens per watt), HPS (high pressure sodium lamps) are typically about 140, and the real winner is LPS (Low pressure Sodium) which can reach 200lumens/watt.

Color rendition is awful unless you like bright yellow, but efficiency wise, LPS clean up.

that would be kewl to have a lps then

quote]PhotonBoy said:


'Sandia has authored or co-authored a number of white papers and general articles which explore the technical challenges associated with solid-state lighting, and the potential impact of solid-state lighting on energy consumption.


[/ QUOTE ]

I'm sure that we're talking truly objective Science here. I mean Sandia itself isn't interested in getting is snout (back) into the public trough, right?

I mean, look, before 1995 LEDs were getting *no light* per watt! I wonder what we thought we were looking at?

I note that without immediate bucks the rapid advances will decline and top out far short of conventional fluorescent lighting (probably real) on schedule. If, OTHO, Bush will only give me half the billions at stake I'll gladly show him a graph of how I'll deliver even more in 25 years.......

So I'm tainted I guess (hey, I work in Materials Sciences, in fact with a guy working with Lumileds on this very topic). We can expect higher energy LEDs (like today's blue and green) to approach the numbers we get from older designs (now optimised), a few fold increase at best. Far, far short of what those seeking funds would claim. There are very real limits on how many photons one gets per watt within a perfect crystal and how many of those one can expect to get out without getting a ticket from the Physics Cops.

Doug Owen

Probably not useful to make a flashlight or search light out of. LPS is a discharge lamp, but not HIGH intensity compared to true HID lighting. They are essentially a monchromatic source, and a 200 watt HID lamp is not much larger then a 150 watt 3 way, a 180 watt LPS is about 3 1/2 feet long, and produced 32000 lumens (yes 10 times the output of a 35 watt HID) for 5 x the power. The only reason it is that short is the LPS tube is folded up inside, the LPS tube is about 6 feet long!

Even the smallest LPS lamps are pretty big.

They make pretty good area lights, and street lights, as a flashlight, FORGET IT!

http://www.lighting.philips.com/nam/products/hid/pdf/p-1785c.pdf

contains typical LPS lighing data for several LPS lights made by Philips.

Astronomer's don't mind them because the spectral output is so narrow, it is easily filtered out. The Color Rendition Index or CR on these lamps is rated at ZERO.

Interesting UK forum re LEDS

''SIGNBOARDS''


Brightnoem