LED vs. incandescent

[highlandsun]

HIDs (and all arc-discharge lamps) must be fully regulated. Once the arc is established the amount of power required to maintain the arc is very low. Without regulation it would runaway until the power supply was exhausted or the electrodes were completely melted/consumed. This is another reason why the complex ballasts are needed. Anyway, these lights don't fade out; since they are regulated their output is constant up to a point then shutdown occurs if there isn't enough power left to maintain the arc current.

LEDs may be more efficient than incandescents but HID is still the most efficient of all. I know some cyclists have been looking into Luxeon-based headlamps but their output and battery life all fall short of HID.

 

[Harri]

Originally posted by Steelwolf:
As to the question of effieciency, LEDs always won in the lower output arena. [...] In the area of high output, high wattage halogen-filled filament bulbs have tended to be more efficient in terms of lumens per watt.

<font size="2" face="Verdana, Arial">Thanks for this info. I kind of suspected it, but had not heard it anywhere.

Originally posted by Sean:
I think you already answered your own question as far as the 1W luxeons go:

<font size="2" face="Verdana, Arial">Well, thanks for confirming me - I was definitely not sure about that stuff. As I've not had the priviledge of owning a LS LED light -yet

Originally posted by Sean:
Considering the regulation eats some of the battery life in the KL1 I would say that LED's are definately competing with incandescents and are more efficient. Not to mention that they don't blow when you drop them.

<font size="2" face="Verdana, Arial">Yes, sounds like it. But they are not as efficient as the lower powered LED's are. The same efficiency doesn't transfer to the current high powered LEDs.

But they seem to better and do not break

Originally posted by Sean:
As far as the 5W emitter it's too early to tell. But if it lives up to it's specs then it should be more efficient than incandescents:

E2e = 5 watt bulb = 60 lumens
5W LS = 5 watt LED = 120 lumens

<font size="2" face="Verdana, Arial">I was just reading in another thread about underdriving the 5W LS... that could apparently be more efficient and if we do not need that much light. Maybe I haven't lost my hope on those 5W LEDs. (The ultimate EDC flashlight design is forming, but that is something for some other thread

)

Did I help any?

<font size="2" face="Verdana, Arial">Plenty. (There is some good stuff in some other current thread also...)

Those HID's are interesting also... but quite in a different light output leaque I guess.

Harri

 

[Jonathan]

Originally posted by Harri:

Yes, sounds like it. But they are not as efficient as the lower powered LED's are. The same efficiency doesn't transfer to the current high powered LEDs.

But they seem to better and do not break

<font size="2" face="Verdana, Arial">Well, not quite. The efficiency of the LS devices and the smaller devices is actually pretty similar, in terms of Lumen per Watt. In fact, I am pretty certain that the LS devices are more efficient, but not by much.

The issue is that the LS devices are big enough require serious heat sinking in order to work, and the smaller devices are being compared to smaller incandescent lamps which are less efficient that full size incandescent lamps. So as compared to similar power incandescent lamps, the LS devices look roughly similar in efficiency, but the smaller devices look super good.

When people built things like caving lights out of large arrays of the smaller LEDs, their efficiency was not much better than incandescent lights, and often substantially lower. But the other benefits of LEDs made it worth the effort.

I was just reading in another thread about underdriving the 5W LS... that could apparently be more efficient and if we do not need that much light. Maybe I haven't lost my hope on those 5W LEDs. (The ultimate EDC flashlight design is forming, but that is something for some other thread

)

Harri

<font size="2" face="Verdana, Arial">Yup, in fact, see this thread:
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=002431

-Jon

 

[Sean]

Originally posted by Harri:
</font><blockquote><font size="1" face="Verdana, Arial">quote:</font><hr /><font size="2" face="Verdana, Arial">Originally posted by Sean:
Considering the regulation eats some of the battery life in the KL1 I would say that LED's are definately competing with incandescents and are more efficient. Not to mention that they don't blow when you drop them.

<font size="2" face="Verdana, Arial">Yes, sounds like it. But they are not as efficient as the lower powered LED's are. The same efficiency doesn't transfer to the current high powered LEDs.

But they seem to better and do not break

Harri</font><hr /></blockquote><font size="2" face="Verdana, Arial">Well not really, lower power nichia LED's are really efficient (by like 10 times) because they are about 10 times dimmer. Does that make sense? In other words, the brighter they make LEDs the more power they need. The more power they need, the closer they get to high power/high drain incandescents like surefires. There is no "free lunch". The brighter they are, the shorter the battery life.

It would be very interseting to see how long a KL1 or Arc LS would run on 2 D cells compared to the generic 2 D flashlight.

 

[star882]

LEDs are slightly better than halogen, but CCFL is even better(including ballast losses).
Only use LEDs where the long life, endurance, and reliablity are important.

 

[lux0]

"LEDs are slightly better than halogen"

in efficiency? no, check again.

 

[James S]

I have followed many of these efficiency discussions. The gist that I have been able to gather is that LED's produce more "usable" light at very lower power levels. halogen and others don't scale down to flashlight size very well. But once over the hump at a couple of dozen watts then halogen can produce much more light for the same amount of power.

I don't know specifically about cold cathode tubes, but compact florescents are considerably more efficient than LED's at the 15 to 30 watt at 120volt level and regular flourescents are even more efficient.

However, when doing real world work with the things you have to take fixture cost and replacement cost into account too. There may be situations where a 50,000 hour LED bulb costing a thousand dollars and being less efficient than a 5000 hour CF will still be cheaper in the long run.

But if you're talking just about power usage, in a flashlight then LED's are a good choice.

-James

 

[Jonathan]

Originally posted by Sean:
Well not really, lower power nichia LED's are really efficient (by like 10 times) because they are about 10 times dimmer. Does that make sense? In other words, the brighter they make LEDs the more power they need. The more power they need, the closer they get to high power/high drain incandescents like surefires.

<font size="2" face="Verdana, Arial">This is not the right way to use efficiency.

The lower power Nichia LED's are not 10x the efficiency of a Luxon. They use less power with roughly the _same_ efficiency.

The term efficiency means power out/power in. So it takes into account the fact that you are putting less power in but getting less power out.

When we talk about lighting, we slightly misuse the term efficiency, by comparing visible light output to electrical power input. This is measured in lumen per watt. The lower power Nichias produce something on the order of 20 lumen per watt, and operate at about 150mW. The Luxeons produce something on the order of 20 lumen per watt, and operate at 1W to 5W.

-Jon

 

[Steelwolf]

If you make an array of 5mm Nichias to operate in the region of 20W to 55W, you will find that the 20W and 55W halogen lamps will produce more lumens per watt, and that the HID lamps will produce even more. The only advantages of using LEDs in this arena are robustness, cooler running (if you don't overdrive it), even colour rendition and increasing efficiency as batteries run down (whereas halogens will dim and become more yellow and become less efficient and HIDs will not even be able to operate once the power source drops below the cutoff level, which is usually quite high).

In the area up to 5W, LEDs will hold their own against incandescents, proving to be as efficient, if not more, with all the usual LED benefits. Remember, though, that brightness is perceived and some will perceive a thin beam with good throw to be brighter than a white-washed area.

As for compact flourescents, they are more efficient than incandescents and a little better than LEDs, but also will only be able to produce an area light. They do suffer from damage as the batteries run down and have a higher cutoff point than LEDs. CCFL were designed not to suffer from damage as the batteries run down but are about as efficient as compact flourescents. The downside is the same problem of needing a ballast and having a higher cutoff point than LEDs.

 

[Harri]

Thanks guys! Some very good info coming out now! Interesting stuff... just makes me more interested about all this!

Maybe I'll have much more options and many different kinds of lights to buy still!

Harri