# Article - "LED Nears Power Efficiency of Fluorescent Lights"



## killsoft (Feb 4, 2006)

From http://www.edn.com/article/CA6383109.html?partner=enews&nid=2019

"""
LED Nears Power Efficiency of Fluorescent Lights

Cree has released the most efficient production *********** LEDs to date.

At 350mA, the XLamp 7090 XR-E produces 80 lm (70 lm/W) typical and 95 lm (85 lm/W) maximum.

This is the first time that production power LEDs have approached the 80 lm/W available from current-generation fluorescent office lighting, but is still somewhat short of the 100 lm/W delivered by the best electronically-ballasted T5 fluorescent lights in production.

The XR-E LEDs are also rated for operation at 700mA, where they produce 160 lm(max), and are the first Cree devices to used its EZBright 1000 die.

The 7090 series have a 7x9mm footprint and the XR-E versions are aimed at general applications, such as street lighting, retail high-bay lighting and parking garage low-bay lighting, as well as consumer products such as torches.

Electronics Weekly is the London-based sister publication of Electronic News, part of the EDN Network.
"""

KS


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## [email protected] (Jan 4, 2004)

Wow, thanks for the article. LEDs are definitely coming into their own.


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## hairball_dh (Aug 7, 2005)

killsoft said:


> From http://www.edn.com/article/CA6383109.html?partner=enews&nid=2019
> 
> """
> LED Nears Power Efficiency of Fluorescent Lights
> ...


Very cool. Been doing a bit of research this am, always looking for the best DIY platform ya know. From an older thread on the innovations forum:


RePete said:


> HID = 50-60 Lm/w
> Halogen = 20Lm/w
> Lux V = 24Lm/w
> Lux III = 26Lm/w (questionable as 3.9v x 1amp = closer to 4watts)
> Lux 1 = 45 Lm/w


Over on the topica bikecurrent forum, the new Cree LEDs are estimated to realistically put out 67 lm/w @ 350 mA and 45 lm/w @ 700 mA.

So just like that, it looks like LED technology is about on par with HID technology, at least looking at the efficiency ratings. There are so many things I like about LEDs that the pendulum has already swung IMO.

I'll report back as soon as I can get my mits on Crees and put them to the test.


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## SocalSuperhero (May 5, 2004)

Everyone always forgets about the lowly 5mm led. Some of the new 5+ lumen 5mm leds are testing at greater than 80lm/w.


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## Low_Rider (Jan 15, 2004)

SocalSuperhero said:


> Everyone always forgets about the lowly 5mm led.


Efficient yeah they're not too bad, but they're a pain to do anything with. They're difficult to focus if you don't like the beam shape, and the huge arrays you need to build to get any decent light output makes them a real pain. You would need 60 or more LED's just to get a measly 300 lumen output. Heat is still an issue for lumen maintenance, and a lack of a substantial physical connection means that the only real heat sinking you can provide is a large ground plane on the back of the PCB.

Yes efficiency is nice, and it's totally possible to build an HID killer with 5mm LED's or other devices currently available (that's the great thing about LED's - highly efficient at lower drive currents), but would the enormous size be worth the efficiency gain?

At the end of the day it's usually total light output that we're after, and I'm more then happy to throw efficiency out the window for a bright light. While battery technology has barely evolved in recent years, it's still more then good enough to power such a light for long enough to go for a good ride with. Having said that though efficiency is nice, and some of the better binned Luxeon emitters and the better binned Cree devices are starting to make people take notice.

As we know, the Cree XR-E in particular has got a lot of the lighting guys quite excited, and for good reason. Most bins have a very low forward voltage (Vf), which is lower then anything else in this "high output" LED category. In terms of efficiency, how does 100 lumen / watt @ 50mA sound?! It simply blows everything else out of the water. 

While the die is rated to cope with a 2 amp drive current, at the moment the packaging and lumen maintenance is not up to it, despite the XR-E's superior thermal resistance. However samples have been tested at 220 lumens at 2 amps (around 7 watts, or 31 lumen / watt). It seems you don't really gain a great deal over 1400mA (200 lumens at around 5 watts or 40 lumen / watt), as there is little increase in lumen output in comparison to the extra current draw. At these kinds of drive currents thermal management will be very important (very aggressive heat sinking), but on a bike we have the advantage of moving air which helps.

It's not just electrical qualities either, as the optical side of things is top notch too. The 75 degree viewing angle produces a beam that is much more useful then other devices. The device will lend itself to reflectors really well, and should produce some huge strong hotspots while still maintaining a really nice strong side spill. Beam shots so far seem to confirm this. A flood with throw? What a monster! :thumbsup: Some guys have been playing with the XR-E by mounting one or more devices sideways in a modified reflector to make the most of the 75 degree viewing angle and the reflective surface of the reflector. Beam shots have been very impressive in terms of suitability for a bike light in this configuration. 

I am yet to receive my Cree devices to do any testing, but there is an interesting thread *here* on the Candle Power Forums which has a lot of interesting information and sample test results for the XR-E. Along with the data sheet, this is where I have got most of my numbers from. Also have a look at a few preliminary beam shots in the above thread, and *here*. Note that they are currently only experiments, particularly in this thread where a 2" aspheryical lens was held by hand.

Finally, it seems some of the guys "in the know" seem to think the next two years will see some rather radical increases in LED performance. What exactly I don't know, the Cree XR-E was a nice jump forward in itself!

HID is dead.

Dave.


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## SocalSuperhero (May 5, 2004)

Agreed, leds are finally starting to put the last nails in HID's coffin.

I'm still hopeful that power leds will come around in efficiency. Actually, I think 5mm leds with their smaller die packages will always be more efficeint than power leds. It's too bad that nobody makes any spider/superflux leds with a narrower focus than 35degrees. Having to deal with optics sucks. You might be surprised at how nice the beam on an array of high output 5mm leds is. Granted, there are individual variations in the beam patterns, but when combined as a whole, it's really quite stunning.

I think you're over estimating the packaging complications of 5mm leds. An array of 55 5mm leds can be packaged into something with a smaller frontal profile than the cateye triple shot. Not only would it out perform the 3x cateye by more than 30 lumens, but it also consumes almost 1/3 of the power that the 3x 3watt luxeons do. Besides, at the end of the day, you stand to loose weight with 5mm leds because you have no optics, no heatsinking, and less battery. Granted, the trade off is increase frontal area for the array, but it's a pretty good trade and a nominal sacrifice at best.

For something that rivals HID at 500-550 lumens you're looking at 4.5 sq inches. That's roughly 100 5mm leds and straight up that's still only 2/3's the power consumption of a cateye triple for twice the output.

As for lumen maintinence, you do have a point. Althought, conserverativly, even at 20ma you can count on output being reduced between 10-20% after 500hrs of use. Fortunatly, even after that reduction in output it's still on par with the cateye triple in output. Not to mention that you could solo more than fourty 24 hour races before seeing that output drop.

Just for comparisons sake, some shots I just took in my backyard.

Overvolted mr11 6v 10watt 12 degree halogen (8.4 volts)









19x5mm leds in an mr11 package ([email protected])









36x5mm leds in a 1.25" round array ([email protected])


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## Blue Shorts (Jun 1, 2004)

SocalSuperhero said:


> Agreed, leds are finally starting to put the last nails in HID's coffin.


You've gotta be kidding. The coffin hasn't even been built. Nice metaphor, though

Here's another one. Don't count your chickens before they're hatched. The best LED lighting systems don't yet have the light ouput equivalent of the run of the mill HID. I'm referring to retail units, not lab experiments.

LEDs are getting better, but they haven't yet approached the total light output of HID. Why don't you wait until there are real LED units that can put out the total light equivalent of HID at the cost and weight of HID... then you can start to celebrate.

LED as getting better. Be patient. The good news is...that as LEDs get better, HIDs will get cheaper. It's all good:thumbsup:


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## Blue Shorts (Jun 1, 2004)

Maxrep said:


> LED's are still several years away. Sorry, thems the facts!


Facts? Who wants facts? It's opinions that matter


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## Low_Rider (Jan 15, 2004)

Think again. 

HID’s have very little scope for improvement, and really haven’t changed significantly in term of power output for years. More efficient ballasts aren’t going to greatly help lumen output either. If you have two identical output ballasts, but one more efficient then the other, it will only be run time that is effected. Recently it’s generally been a battle between HID bike light manufacturers on who can make the most stylish looking light.

Lithium Polymer cells are not new, and in terms of power density are no major leap forward. Your argument that they can be used to power higher wattage HID’s neglects the fact that they can also power larger higher wattage LED’s and arrays. 


Take an example. Your Lupine Edison is rated at 950 lumens at 16 watts.

With 6 XR-E’s of the same bin as tested in the first link I posted, you could easily achieve 960 lumens with a 15.8 watt power draw. Depending on the bin you could quite easily end up with a far superior colour temperature too. Then think about what you’re doing with the light produced. With HID your limited with how you are actually projecting that light. LED based lights have huge scope for various reflector and optic designs.

Weight is another topic that has been mentioned, and it’s one area where LED based lights excel in comparison to HID’s with their heavy ballasts. If you look at most LED based light on the market today, even with their current heavy heat sinking demands, you still see at least a 200 gram difference. It will only improve later on too.


Yes I agree, this current wave of technology will take a while to hit the shelves, but these hypothesised HID increases aren’t going to hit the shelves any time soon either. The great thing about LED’s is that a good design will allow then to be upgraded very easily. Take the Lupine Wilma for example, already it has been released with a number of different emitter upgrades, and there would be nothing stopping you getting your light upgraded when future LED’s hit the market. :thumbsup:

And yes, most of this debate is opinion (it is a forum after all), but the basis is published fact, released by manufacturers, and tested by hobbyists and engineers.


Sorry folks, but from my point of view HID is dead and buried. 

Dave.


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## langen (May 21, 2005)

Low_Rider said:


> Sorry folks, but from my point of view HID is dead and buried.
> 
> Dave.


agreed!


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## [email protected] (Jan 4, 2004)

Low_Rider said:


> Think again.
> 
> HID's have very little scope for improvement, and really haven't changed significantly in term of power output for years. More efficient ballasts aren't going to greatly help lumen output either. If you have two identical output ballasts, but one more efficient then the other, it will only be run time that is effected. Recently it's generally been a battle between HID bike light manufacturers on who can make the most stylish looking light.
> 
> ...


Dave,

You took the words from my mouth.  The other thing that will keep the cost of HID high -- they will never be as cheap as halogen... ever -- is that there is, I believe, only one manufacturer of miniature HID bulbs, Welch Allyn and they patented it. This is one reason the bulb costs are so high.

It all boils down to Lumens/Watt and the Lupine sited above is sitting at 60Lumens/W. The Cree LED in the original article is at 70 Lumens/W. Sorry, that trumps the HID.


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## Low_Rider (Jan 15, 2004)

> Dave, your last post was chocked full of fruitless and wish full speculation.


Speculative yes, but based on solid proven fact. I don't have to wish for anything. It's happening.

I am open to correction, but I have not heard even a whisper of any major "HID advances" as you claim. Sorry if I came across argumentative, but I was just trying to prove the point that any advances in battery technology will benefit all forms of lighting, not just HID. Lithium Polymer cells have been about for 8 years or more and in terms of energy density really hasn't moved forward in leaps and bounds.

Same with your ballast comment, yes it may give you a negligible gain in efficiency, and more efficient ballasts will help lumen / watt figures. But again electronic ballasts are nothing new and certainly not of major significance that is worth writing home about.

From the onset of this thread we were discussing a product which has only recently been released and it will be a while off before lighting manufacturers incorporate it into products. In my last post I only drew comparisons, and explored some of the advantages of these LED devices.

Far from a pointless rant I hope. In the deep end, nah I have plenty of light to find my way out!


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## Low_Rider (Jan 15, 2004)

> Oh, geeze. You guys need to see an Edison in action!


I have seen a couple in action, and they're a great light.

Hopefully it won't be too long before we'll be able to compare a similar lumen output Cree XR-E based light to one.


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## Blue Shorts (Jun 1, 2004)

Low_Rider said:


> Sorry folks, but from my point of view HID is dead and buried.
> 
> Dave.


Wow. ..and we've won the war in Iraq, too

I tend to ride in the real world. My HID lights completely overpower the currently available LEDs out there. It's no contest.

I'll be happy to jump on the LED bandwagon when an LED system is available that has a higher output than HID and a similar cost. Until then, I'll be ridng with brighter lights.


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## itsdoable (Jan 6, 2004)

I'm with Dave, LEDs are the future. There are commercial 12W LED systems that are comparable to similar wattage HIDs now. But pure lumens does not say it all, LEDs have a more efficient neutral white colour, they can be dimmed to almost any power with greater efficiency, you can turn them off whenever you want, you can limp home on them when your battery is depleted, they don't feel like someone has tied a lead weight to your head, and when you drop one on the concrete while fumbling with the mount, you don't have to fork over $150 for a new bulb.


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## Blue Shorts (Jun 1, 2004)

Maxrep said:


> The bottom line is that your time line and optimism for the LED may not be that realistic for the next 3 years or so. I get my gear at cost. The moment I see something on the horizon that is better in terms of price and performance, I'm there - heck, were all there. I just wouldn't want anyone to not enjoy this night ride season because they think purchasing an HID now, would be an unwise decision.


Thant's my point, too.

I think we're all in the same boat. I want a high performance LED system as much as everyone else, but they're not quite ready for prime time. Until then, I'm enjoying a lot of great night riding using "relatively" inexpensive HID systems.

It's a bit premature to call HID "dead" since there's nothing to replace it right now


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## killsoft (Feb 4, 2006)

Low_Rider said:


> <snip>
> 
> Hopefully it won't be too long before we'll be able to compare a similar lumen output Cree XR-E based light to one.


If I were a betting man, I'd bet that we will see an HID-killer before summer.:thumbsup:

KS


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## Low_Rider (Jan 15, 2004)

Maxrep said:


> The practical application has just recently graced us, as a safe charging method for li-poly batteries and the consumer, was somewhat illusive. Though I don't own any RC (remote control) cars or plains, the li-poly batteries are taking over that hobby due to their light weight and mAh capacity. This has largely taken place in the last year.


Many of the RC crew have been running Lithium Polymer cells for well over 4 years now. In fact until then they were inferior to Lithium Ion in terms of power density and they really haven't improved much more then current Lithium Ion cells (typically 15% over Lithium Ion).

The reason why Lithium Polymer cells are lighter in comparison to Lithium Ion is because they don't require the metal casing which is required with Lithium Ion cells to press the electrodes and separators together. With Lithium Polymer cells this isn't required as the separator sheets are laminated. In terms of safety Lithium Polymer really aren't all that better than Lithium Ion. The chances of self-failure are a lot lower, but if battery protection circuits aren't used they are just as volatile as Lithium Ion during charging and discharging.



Maxrep said:


> Odd that you discount the future usefulness of the li-poly as it pertains to HID, or the more powerful metal halide bulbs that could be utilized in tandem, yet you lend your ideas of LED all manner of scope of possibilities in the future.


I'll repeat my previous post. The only gains in better battery technology will be in capacity, weight and safety of the cells. A bigger capacity battery isn't going to make any light any better in terms of lumen / watt efficiency, it will only give you a better runtime.

You mention that "more powerful metal halide globes" could be used in tandem, but yet again it doesn't make such a system any more efficient. You're effectively doing the same thing as using LED light arrays in tandem. 

I am yet to find any documentation of recent advances in HID technology.



Maxrep said:


> The bottom line is that your time line and optimism for the LED may not be that realistic for the next 3 years or so.


Sorry but I don't recall setting any timelines in my posts in this thread for the implementation of these devices into products. I'm not sure where you got the figure of 3 years from either.

Interestingly enough, Lupine were releasing the Wilma with Luxeon K2 emitters within a couple of months of the devices being released. I know of a number of smaller scale flashlight manufacturers who are already building prototypes of Cree XR-E based lights. It would be naive not to assume that most lighting manufacturers who already have LED based products have their engineers playing around with these devices already.

And just to stir up more trouble, have a read of *this interview* with Mark McClear, the solid state lighting director at Cree. Please note that by commercial product Mark is referring to the bare LED emitters as released by the company, not finished lights built by manufacturers. :thumbsup:



compoundsemiconductor.net said:


> Historically, there is roughly a one-year time lag between developments in Cree's research labs and turning that breakthrough into a commercial product. Recently, the company produced laboratory LED's with an efficacy of 131 lm/W. "If historical trends continue, next year should see a commercial XLamp device with efficacy above the 100 lm/W range," said McClear.


Dave.


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## lidarman (Jan 12, 2004)

I'm not sure I buy your argument for HID. I have an HID light and it has lots of output at the price of a heavy lamp housing, a long turn-time and poor performance in the cold. 

LEDS are just below this performance with instant turn-on, ability to PWM dimming, lighter weight, better physical robustness, and long lifetimes of LEDs. HID lamps degrade rapidly at a few hundred hours of use while LEDS are in the 1000 hr ranges. 

I think dimming is a big thing in lighting because you don't always need 1000 lumens blasting. I made a dimmer on my halogen light and ...so what I wound up doing was using two lights--one halogen and one HID.

I am with the school that HID is dead...least in my eyes. I won't go out and buy another HID system, in fact, I might have mine for sale soon.


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## Blue Shorts (Jun 1, 2004)

lidarman said:


> ...so what I wound up doing was using two lights--one halogen and one HID.
> 
> I am with the school that HID is dead...least in my eyes. I won't go out and buy another HID system, in fact, I might have mine for sale soon.


So let's see. You say that HID is dead, yet you are using one. 

How about if we compare reality to reality? Let's compare what are arguably 2 of the best lights out there for total output. The Lupine Wilma 8 12W LED and the Edison 5 16W HID.

The LED system gets 35 Lumens/W with a maximum output of 420 Lumens. The HID gets 56 Lumens/W with a maximim output of 900 Lumens.

So, in the real world, the HID is far more efficient, and far brighter than the LED system. At equivalent light outputs, the HID is lighter because you can use a smaller battery due to it's higher efficiency.

I've never had the problem with a light being too bright. If Idid have that problem, I'd go out and buy an LED light

In the real world... the HID is brighter, lighter, and more efficient. The useful life of the lighthead is about 700 hours, which is about 6 years for my 4-6 hours/week for the 20 weeks /year that I use it. I'll most likely get the latest and greatest every 3-4 years, so longevity is not even an issue.

When LED surpasses HID in efficiency, weight, and total output....with a real available retail system...THEN you can call HID dead. Until then, you're talking nonsense.


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## LyNx (Oct 26, 2004)

Well I think that this is where LED's are at right now, the "If I buy this light this month will something better come out next month?" I was all set from reports to buy a Cateye Triple Shot LED lighting system, but then I heard it wasn't as bright as HID"s. I said OK so it's not AS bright, but nearly as bright and it's a lot cheaper than HID systems right - you can pick up a Triple Shot for about $230 or under, HID start at $400 right? Well then I saw the NR Enduro at around the $250-270 price range and thought HUM seems you can get AHID sysatem almost as cheap w/ a brighter lgiht.

So I did some more research and find out that not even a year after release Cateye has released a new Triple Shot "Pro" that's twice as bright as the original for $300>. So if I'd rushed out and bought the original I would be feeling real bad now and feel good that I waited and NR put together the Enduro kit to get people into HID's.

Just a laymans opinion is all. I judge stuff by what I can buy over the counter/order online and just plug in and go. I'm not an eletrician and don't want to be messing with soldering, circuit boards etc. I think it's great the LEDs are improving rather rapidly, but don't quite see them replacing HIDs anytime soon for the price to light output ratio they provide.



Maxrep said:


> .......... I just wouldn't want anyone to not enjoy this night ride season because they think purchasing an HID now, would be an unwise decision.


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## California L33 (Jul 30, 2005)

The brightest lights _today_ are HID, no doubt (usually ridden by somebody who doesn't know to angle it a few degrees down and right like a car/motorcycle headlight so as not to blind oncoming cyclists on the trail). I've seen some bright LEDs out there, too, but nothing that makes me want to dump my (dented) 30w halogen system yet. What it gives me that other systems don't is reliability- it has two lights, with two switches (a switch failure that took out both lights prompted me to modify the Cygolite single switch design), and with a spare battery chances are I'm not going home without light. I get plenty of light for a 2 hour night ride on one battery. It's a 6V system and the 10 watt bulb is a bit yellow, but I don't honestly think a blue-white bulb makes you see more, even if it is prettier. (The replacement 20 watt bulb is a nice blue-white.) 

Still, like everybody else, I want more light, more run time, and lower weight- all in a smaller package. That's why I came here and did a search for "Cree" after hearing about the Xlamp- to see if there were any commercial systems available yet. When one comes along that puts out a nice broad, even light as bright as my halogens, I'll be tempted. 

You know, a thought just occured (it happens once in a while), the new generation LEDs might actually make the bike mounted generator useful. A hub generator through a regulator, and a small capacity battery to run the LEDs at low speed/stop, might be just the ticket. It would sure add to the care-free factor of not having to worry about charging batteries- you want to ride at night- just go. That would be nice.


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## Blue Shorts (Jun 1, 2004)

A yellow-ish light is probably more useful than the color that is output from HID or LED.

Yellow is the last color that the human eye can distinguish in low light conditions. Personally, I prefer the Halogen light color to the HID or LED colors. It gives a warmer, more natural feel to the landscape and at similar light levels, the details are easier to see.

The only reason I use the HID is for run time and total light output. An HID with a more yellow color light would be great.


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## LyNx (Oct 26, 2004)

I don't know, maybe it because my Halogen is only 2-6W bulbs but I find the colour too yellow and find the bluer/colder lightt of the LEDs and HIDs easier to see by. Even the newer Halogens are coming with a more bolue type light colour.



Blue Shorts said:


> A yellow-ish light is probably more useful than the color that is output from HID or LED.
> 
> Yellow is the last color that the human eye can distinguish in low light conditions. Personally, I prefer the Halogen light color to the HID or LED colors. It gives a warmer, more natural feel to the landscape and at similar light levels, the details are easier to see.
> 
> The only reason I use the HID is for run time and total light output. An HID with a more yellow color light would be great.


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## [email protected] (Jan 4, 2004)

Maxrep said:


> Definately correct. An HID light that has a color temperature rating of 10,000 to 12,000(white to blue / white) Kelvin, will appear less natural to the eye. Sunlight is aproximately 5500 to 6000k.


HID bulbs and the new LEDs are around 5000 to 5500 Kelvin. Not 10,000. They are pretty close to sunlight.


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## achesalot (Nov 8, 2005)

Well, I was gonna stay out of this, but seeing that some folks are talking out their saddle warmer, I might as well add my two cents.

Both LED and HID are great tech for bike lighting. Each have their advances from time to time. Lately there have been some breakthroughs in LED tech, and this will probably be a good year in that area... most likely putting LED lights on common or higher lumen/watt ground with HIDs. And that's coming fairly soon for LED homebuilders...(my Cree XR-Es should be here any day!) It'll take several months for the big name bike light manufacturers to get on board. I haven't heard any news on the wire lately of breakthrough advances in HID tech, but I'm sure Welch Allyn is always looking to improve its lamps and hopefully lighter, more efficient ballasts will be developed.

Battery tech advances don't offer any advantage for HID. Advances in battery tech apply across the board for both lighting technologies. So it doesn't make sense to posit that as an HID advantage.

So now that we've arrived at the point in time where LED light tech is on equal or higher ground with HID, when all other things are considered, the LED will indeed become the nighttime trail illumination of choice. It will be cheaper, lighter, more durable, longer lasting, instant-on, continously dimmable, and have better color tint. Is the HID dead? Maybe not yet, but it does face some serious competition in the coming year once bike light manufacturers are able to sell off old stock and gear up with the new gen LEDs. Now I wish there was some new tech that was threatening gasoline engines in a similar way.


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## achesalot (Nov 8, 2005)

Maxrep. I think you've sort of missed the point of this thread's starting post... which was about a light-producing device that is more efficient in terms of lumens per watt. Not that we can get higher amp hour batteries and drive 30 watt HIDs or 30 watt LED arrays. I don't think the originator of this thread (killsoft) intended it to be an HID vs LED debate (or maybe he did set us up for that  )

Take the Lupine Edison-10 HID: (man they do come with a hellacious 12.8 ah battery!)
16 WATT setting (950 LUMEN) = 59.4 lm/watt
10 WATT setting (500 LUMEN) = 50 lm/watt

and from the first post in this thread:
"At 350mA, the XLamp 7090 XR-E produces 80 lm (70 lm/W) typical and 95 lm (85 lm/W) maximum."

So you can see that in terms of an efficient light producing device, HID is already beat... now... today. In terms of bike lights currently being manufactured, sure HID lights put out more lumens of light... without a doubt. No argument. 

A 3 LED bike light similar to the Cat-eye Triple Shot configuration with 3, Q2 binned XR-E LEDs will put out about 540 lumens and consume just under 9 WATTs. That's 60 lm/w. I will have one of my own construction by the end of the year. It cost me about $100 to build the light. I'm using a 4A Li-Ion battery that cost under $80 (including charger). Not for everyone, but for cheapos like me, who can't afford a new HID system each fall, it's a nice alternative and much safer to build than a homebuilt HID (ballasts put out 6,000 volts to start the arc action). Besides, most of us homebuilders also enjoy the challenge.

A little enlightenment from a "grasshopper."


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## California L33 (Jul 30, 2005)

LyNx said:


> I don't know, maybe it because my Halogen is only 2-6W bulbs but I find the colour too yellow and find the bluer/colder lightt of the LEDs and HIDs easier to see by. Even the newer Halogens are coming with a more bolue type light colour.


 My guess is that you've got a brightness problem. The original configuration of my Cygolite was 25w, one 15w plus one 10w. These were both "yellow" bulbs and they provided enough light for anything but a road bike descent. The human eye is probably most sensitive to daylight, around 6500 degrees Kelvin. The "yellow" light of a 6V halogen is, I'd guess, around 3500k. The blue/white of "blue" halogen is probably close to daylight. HID is going to be higher than that, but HID isn't a "full spectrum" light. This means you'll get horrible color rendition from it, but if the light is in a spectrum easily visible you'll see more- unless it happens that you're illuminating something that absorbs that spectrum. Which is best? It may have something to do with the individual, as the human eye/brain system is a "relative" system (there is nobody with "perfect color pitch") and may vary from person to person. In general, I'd guess the system that puts out the most lumens in a visible spectrum (full or not) will give you the best system for a bike (finding the path/avoiding obstacles).


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## achesalot (Nov 8, 2005)

Yeah, I figured it was that "HID is dead" statement that started the flame war.


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## 1440Brad (Apr 26, 2006)

*Yes and No*



California L33 said:


> My guess is that you've got a brightness problem. The original configuration of my Cygolite was 25w, one 15w plus one 10w. These were both "yellow" bulbs and they provided enough light for anything but a road bike descent. The human eye is probably most sensitive to daylight, around 6500 degrees Kelvin. The "yellow" light of a 6V halogen is, I'd guess, around 3500k. The blue/white of "blue" halogen is probably close to daylight. HID is going to be higher than that, but HID isn't a "full spectrum" light. This means you'll get horrible color rendition from it, but if the light is in a spectrum easily visible you'll see more- unless it happens that you're illuminating something that absorbs that spectrum. Which is best? It may have something to do with the individual, as the human eye/brain system is a "relative" system (there is nobody with "perfect color pitch") and may vary from person to person. In general, I'd guess the system that puts out the most lumens in a visible spectrum (full or not) will give you the best system for a bike (finding the path/avoiding obstacles).


The light produced by the HID is a "blue" color when you are looking into the lamp. When you are behind the lamp, as you would be using it, the lamp does not look as blue, and more resembles the output of natural sunlight. There have been many studies done in the trucking industry that show the light output of HID produces less eye fatigue to the user. Many truck manufactures (Freightliner) are looking to offer HID systems. This shows that the "blue" light is more efficent to the human eye than the "yellow" light produced by a halogen bulb.

The technology in LEDs is being advanced leaps and bounds, but it will be a while before you see HID being overtaken by LED. 
Lighting is tested for output in a dark tunnel with a photo receiver placed at one end facing the light. LEDs receive high marks for light output as measured this way because of the very narrow beam produced, but the ammount of light that is broadcast by the LEDs are less than that of the HID. This is where LED designers are making progress in widening the beam and using a reflector to brodcast more light.
We are using some of the new Cree and Lumiled products with great results in "task" lamps, but are still working on headlamps.


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## California L33 (Jul 30, 2005)

Maxrep said:


> We all understand the point of the thread. The digression came about quickly as it took only a couple of posts for the HID light to be repeatedly pronounced dead. This was an incorrect statement.
> 
> All of us here, myself included, welcome the advances of LED technology - who wouldn't? It is worthwhile to point out the fact that the advances in the LED light do not equal instantaneous implementation in the cycling industry. It takes time....more time than some are willing to acknowledge.
> 
> ...


 If all the new LED systems do is drop the price of HID I'd be happy. As I said in another post, the only thing I'm not comfortable with using a 30w halogen system for is high speed on a road bike, but I'm not going to lay out multiple hundreds on an HID system then worry about overheating a $99 bulb every time I come to stop. As others have pointed out, most of the price of those systems is profit, in terms of "top of the line" perception and proprietary technology. When they see the wolf at the door the prices will come down.


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## Speedub.Nate (Dec 31, 2003)

California L33 said:


> If all the new LED systems do is drop the price of HID I'd be happy. As I said in another post, the only thing I'm not comfortable with using a 30w halogen system for is high speed on a road bike, but I'm not going to lay out multiple hundreds on an HID system then worry about overheating a $99 bulb every time I come to stop.


I'm down with that.

I poo-poohed HID from the get-go due to expense, bulb failures and (at the time) problems reported with still immature electronic control systems being used (that issue seems to be cleared up).

I've been happily running the same halogen NiteRider Classic dual beam for about 10 years. I, too, have benefitted from improved capacities and chemestries in battery technology.

As a satisfied halogen user, I'll have the biggest benefit in the next year or two when I switch over to LED lighting systems -- the whole "HID vs. LED" debate is nearly irrelevent to me.

I'm not as concerned with system weight, but I certainly don't like paying $15 for spare bulbs and could benefit from slightly extended run times.

I've been following this thread with great interest. The niggling question in my mind, and perhaps many others, is likely a common one: *When should I jump in if the next "great leap" in LED technology is so clearly on the horizon?* (A common refrain of the modern day consumer!).

So nevermind HID... where is LED technology in relation to a 30w halogen system?


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## LyNx (Oct 26, 2004)

yeh mine happens to be a Cygo aswell and yes the light seems to be "dimming" with age - 2 years old now. I am looking into changing the connection and using a higher voltage RC battery to over-volt the light and see if that helps, it's served me quite well for the 2 years so if it go boom I won't feel too bad.

About the colour thing I am quite noted for my very accute sense of colour and very minimal differences are easily seen by me - I'm a graphic artist and photographer and I can detect a colour differences were most people say "what's different about those 32 pics" and am called on for it all the time. But yes everyone has different colur perception and what's makes seeing good for one person may seem not so good for another.

My first real ride with the HID will be on Tuesday and then I will know for sure if I really like it's colour or not. If it's a bit too cold for me I may add a 5cc Yellow photographic gel in front and see how that effects things.



California L33 said:


> My guess is that you've got a brightness problem. The original configuration of my Cygolite was 25w, one 15w plus one 10w. These were both "yellow" bulbs and they provided enough light for anything but a road bike descent. The human eye is probably most sensitive to daylight, around 6500 degrees Kelvin. The "yellow" light of a 6V halogen is, I'd guess, around 3500k. The blue/white of "blue" halogen is probably close to daylight. HID is going to be higher than that, but HID isn't a "full spectrum" light. This means you'll get horrible color rendition from it, but if the light is in a spectrum easily visible you'll see more- unless it happens that you're illuminating something that absorbs that spectrum. Which is best? It may have something to do with the individual, as the human eye/brain system is a "relative" system (there is nobody with "perfect color pitch") and may vary from person to person. In general, I'd guess the system that puts out the most lumens in a visible spectrum (full or not) will give you the best system for a bike (finding the path/avoiding obstacles).


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## achesalot (Nov 8, 2005)

Speedub.Nate said:


> So nevermind HID... where is LED technology in relation to a 30w halogen system?


Here's where:
30W halogen system puts out around 600 lumens.
Nextgen 3 x Cree XR-E LED 9W @ 540 lumens.
But don't jump quite yet. No bike light manufacturers are producing these yet.

I agree with the last few posters. Any new tech will be good for everybody in terms of $/lm value.

Bike light manufacturers do seem a little slow to adapt, and the current gen of LED bike lights is grossly overpriced in my opinion. Come on, $300 (decided not to mention manufacturer) for one 5 watt LED? I can buy a 5 watt Luxeon V LED for $28, and I'm sure the manufacturers buy in bulk. Luxeon IIIs stars are about $8 ea. I know they've got to package it with a driver, lens/reflector, and supply a battery (which can be expensive if Li-Ion), but it's a bit of a rip off and I see where it makes some folks poo poo the currently manufactured LED lights, especially compared to the output of HIDs. I know they've gotta make a profit and all ... but come on. I can buy a real nice 5 watt Luxeon V flashlight for about $65, stick some rechargable RCR123s in it and whalla... man I'm cheap!


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## Roger G (Feb 10, 2005)

*12 Cree LED or one Supernova dual beam HID?*

Just wanted to point out one thing:
LEDs may be as efficient or even more efficient than HIDs,
but (as someone stated above) you will need about 6 Cree LEDs 
to replace a good single beam HID (There even is a dual beam HID out there).
One Cree illuminant has a diametre of approx. 1 inch (a guess, I can go and 
measure it tomorrow) - where do you put all the reflectors?
That's going to b a monster light. Maybe interesting for cars, but not for bikes.

A single or dual beam Cree LED will be great, but HIDs will still rule the
"ultra-bright" section of the market for some years.


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## achesalot (Nov 8, 2005)

Roger G said:


> Just wanted to point out one thing:
> LEDs may be as efficient or even more efficient than HIDs,
> but (as someone stated above) you will need about 6 Cree LEDs
> to replace a good single beam HID (There even is a dual beam HID out there).
> ...


The cree emitter is 7mm x 9mm (1/4" x 3/8")
3 of them should output about the same lumens as an 11 watt HID

Yeah, to get the output of a 13watt or 16watt HID, you would a 4 or 5 emitter light.


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## killsoft (Feb 4, 2006)

Speedub.Nate said:


> <snip>
> I've been following this thread with great interest. The niggling question in my mind, and perhaps many others, is likely a common one: *When should I jump in if the next "great leap" in LED technology is so clearly on the horizon?* (A common refrain of the modern day consumer!).
> 
> So nevermind HID... where is LED technology in relation to a 30w halogen system?


That's always the question: when to jump in. The advances in LEDs will drive the price of lighting down, but only after sufficient profit has been wrung out of existing products. You'll pay large bucks as an early adopter, and be frustrated as the technology improves and the price lowers for what you bought a while ago. I like to wait until an implementation of technology has settled a bit, and let the "lifestyle" buyers finance the first run.

If you have a system that works for you now, I say wait to replace. The sweet spot in LED bike light performance and price hasn't arrived yet. The good news is that the technology now exists, as evidenced by the Cree.

KS


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## Blue Shorts (Jun 1, 2004)

achesalot said:


> Yeah, I figured it was that "HID is dead" statement that started the flame war.


Yep...That that's the statment

Most of us here are in agreement. We all want better, lighter and cheaper lights.

Right now, HID rules the roost in terms of light output. Hopefully, the new LED's will be available in bike lights soon. I'll jump on the bandwagon when they are. Until then... I love hearing about the advances in LED technology. I just get a bit miffed when some people prematurly decide that a currently superior product is "dead".

I hope LED's can replace HID... and as soon as possible.. but until then, I'm happily riding with some of the brightest and conveinent lights out there... and they are very reliable.

Someone here mentioned that the HID's overheat when you aren't moving. that's not correct. halogen will, but not a properly designed HID.


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## Roger G (Feb 10, 2005)

Blue Shorts said:


> Someone here mentioned that the HID's overheat when you aren't moving. that's not correct. halogen will, but not a properly designed HID.


Tell that Lupine.  
It's never the HID bulb itself, but the electronics behind that usually overheat.


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## itsdoable (Jan 6, 2004)

Speedub.Nate said:


> ... I've been following this thread with great interest. The niggling question in my mind, and perhaps many others, is likely a common one: *When should I jump in if the next "great leap" in LED technology is so clearly on the horizon?* (A common refrain of the modern day consumer!).
> 
> So nevermind HID... where is LED technology in relation to a 30w halogen system?


Not any time soon. There are several commercial systems out there that put out enough light to ride singletrack (Cateye triple, Nightlighting, DiNotte Ultra-5s, Lupin Wilma etc...), but nothing that is a bright as an HID. Also, since the chip technology is progressing at a fairly rapid rate, like computers, anything you buy today will be out of date in a year.

Most reputable companies like to field test thier products for a season (at least) before offering them for sale. It's just smart business. So the specs you see today (which are usually based on the best of a batch - which you won't see in over-the-counter chips) won't be in a product for a year or 2, and then there will be better chips anounce already, so its a vicious circle.

There's nothing wrong with halogen technology, it's simple, durable, and works. HID's are a bit more finiky, but very reliable these days. For us DIY light geeks, we'll always play with new stuff, like LEDs and spiral Fluoresents.

As to when you should jump in - when they produce a product that is a) bright enough for you, and b) in your price range.



Blue Shorts said:


> Someone here mentioned that the HID's overheat when you aren't moving. that's not correct. halogen will, but not a properly designed HID.


A halogen will overheat? If a _properly designed_ HID won't overheat, then there is no way a _properly designed_ halogen will overheat.


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## bikeny (Feb 26, 2004)

*What current for th Cree?*

I am glad to see there are some more people who will be playing with the Cree LEDs shortly, as I also have some on order. I am also planning to to build a 3 LED bar light to replace my DIY HID that I have been using for the last 5 years. My question is what current will you be running the LEDs at? I know the data sheet says max 700 mA, but I believe I have seen references of people driving them at 1000 mA? Also, what current regulators will you guys be using? I am looking at either an nflex or one of the Buckpucks from Lumileds. The nflex looks nice, can be set to variety of currents, but has way more features than I need! The Buck puck can be bought in either 700 or 1000 mA configurations, and with a 3 way switch and a resistor gives you full power and a low power setting, which is really all I need. I will be sure to post pic's when I get something built.

Mark


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## Jamieson (Nov 16, 2006)

*Cree currents*

I've got two Cree XR-E's mounted on an aluminum heat sink and they're running at 3.3V @ 700mA. The heatsink gets slightly warm after an hour or so (no forced air movement). Two devices running at 350mA doesn't produce much heat at all -- hardly noticeable.

From the datasheet I assume that they're putting out about 135 lumens each for a total of 270 lumens @ ~58 lumens/watt. Very, very bright light. The Cree optics (see the Cree website) are inexpensive and focus the light into a moderately tight beam that is devoid of any hot spots or rings, etc. I paid about $9 each including optics.

My plan is to put two of these in a small machined aluminum enclosure and run them at 700mA using a boost converter ("fatman" from taskled.com). Here's my math:

LED power: 2 * 3.3V * .7A = 4.62W 
LED output: ~270 lumen (58 lumens/watt)
DC-DC converter efficiency: 90%
Battery Power: 4.62 / 90% = 5.13W
Battery Capacity: 4 * 1.2V * 2.5AH (NiMH AA cell) = 12WH
Runtime = 12WH / 5.13W = 2.3 hours

270 lumens for 2 hours from 4 AA batteries! Cool! 

have fun, 
Jamieson


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