Heat dissipation of the U2 at 100+ lumens...how?

I can't sleep at night! I am plagued by a question that must be addressed by someone. I would like to know how the U2, which will be sporting an output in excess of 100 lumens on high, will be able to dissipate the heat generated by it's 5 watt Luxeon?

My theory...
There are three other lights using 5 watt Luxeons and two 123 batteries, the L4, L2 and L5. We know that the L4 doesn't have enough body mass to dissipate the heat it generates after about 15 minutes, because the bezel gets very hot. Some of us get into the habit of "not" leaving it on too long, even if we want to, because we want our Luxeons to have a long lifespan. I don't think that the L2 has the same overheating problem as the L4, because it is so long that it draws the heat out of the bezel and has more metal further away to keep the bezel cool. The L5 doesn't have an overheating problem. It has more body mass than either light, to absorb heat. It so happens that it is very close in body mass to the U2. The bezels have the same 1.47" diameter, so the heat generated by the U2 at that spot, will have the same means of escape as the L5. The lengths are almost the same.

If the L5 is putting out in excess of 65 lumens, and the U2 is projected to be putting out over 100 lumens, then there must be some mechanism in place allowing the Luxeon to run cooler. Since I am not well informed on Luxeon binning, I am guessing that the Luxeon selected for the U2 must be of such a bin code, that it can put out more light and generate less heat. I think that the word that best describes this general characteristic is efficiency. If my theory is correct, then the Luxeon bin used for the U2 is top notch, and the U2 with it's high output must generate less heat than the L5. Despite this being a logical theory, I may very well be wrong. If I am, I would like to be told so, and at the same time informed of any other possible theories. Most of us are not sure of anything inside of the U2. SF wants it this way, and I accept this.

Yeah, I'm concerned to. IIRC, under NORMAL conditions (driven normally with a good heatsink) a 5 watt luxeon is rated at only 500 hours to 50% brightness. If the U2 is overdriven (which it sounds like it might be), that number could be less. 500 hours LED life might be a lot compared to a incandescent, but the slightly less powerful 3-watt luxeon dwarfs the 5-watt in LED life (10,000 to 20,000 hours to 70% IIRC) when driven within normal range and well heatsinked.

Maybe that's where all the W and X binned 5-watters ran off to? Really, your theory could very well be right. But I'm still not sure that the U-2 will make 100 lumens. I remember Don saying that it seemed pretty much like an L5 on high. Of course, I hope for 100 lmn. It would make sense in a dimmable light. You don't need high all the time, and having lower levels means you can save batery life and keep things cool until high is needed.

Re: Heat dissipation of the U2 at 100+ lumens...ho

remember, an X-bin puts aut 192+ lm in theory.
bernhard

Re: Heat dissipation of the U2 at 100+ lumens...ho

My Xbin only gets slightly warm driven by BB750 in a PR head.

Re: Heat dissipation of the U2 at 100+ lumens...ho

192 to 249.6 lumens...........to be exact, according to this Luxeon pdf file Luxeon Binning - AB21 If they use U-bin or V-bin, I would be happy. With a W-bin, one could toast marshmallows. An X-bin would heat up a small room........... Nice try Bernhard. We all want more light than we can possibly use.

Re: Heat dissipation of the U2 at 100+ lumens...ho

Also, don't forget the large amount of heat some converters can make, where as others run quite cool.

Re: Heat dissipation of the U2 at 100+ lumens...ho

Luxlover,

You seem really stuck on the stated Lumen ratings which I understand but I suggest that the 65 was based on 5W's back then and the 100 is based on more current LED's. The higher the luminous output in bin, ceterus paribus, the lesser energy wasted in heat. You seem to be suggesting more heat as the flux bin increases?!?!?

The U2's rating is obviously based on the high level selection of output. I would think that anyone planning on running their U2 on high most of the time is likely selecting the wrong tool. I would expect that the U2 current setting for high might be in excess of the KL5 given the fact that the light *does not* have to be "floored" all the time. If a typical U2 was slightly overdriven on high and it consisted of a W bin LED and say the light getting out the front end were say 70% of lumileds flux rating, what would the anticipated luminous output be? Is 70% reasonable? /ubbthreads/images/graemlins/icon3.gif I'd offer to do some bench testing myself but my wife has the integrating sphere and won't give it back! /ubbthreads/images/graemlins/blush.gif

Re: Heat dissipation of the U2 at 100+ lumens...ho

I remember Al saying that the L5 may in fact produce 100 lumens back then when it was made available but that SF simply didn't brag about it right away; the 65 lm rating of the L4 would then have comfused everyone about the lumens rating of the 5W line of SF.
How does the U2 dissipate this heat?
How do the L5 or L6 do it?
I wouldn't worry about it but it's just my 2cents... /ubbthreads/images/graemlins/icon3.gif

Re: Heat dissipation of the U2 at 100+ lumens...ho

the L4 makes abotu 80 lumens to start, as Peter mentioned when he had some lights sent to a firm with an integrating sphere. it shouldn't be too hard for the L5+ and U2 to hit 100 then.

Re: Heat dissipation of the U2 at 100+ lumens...ho

Yes, the L4 puts out more than 65 lumens, and the L5 and L6 put out even more than the L4, even so Surefire only claims 65 lumens for all of them. The Surefire ratings are conservative. I suspect Surefire has decided not to use Luxeons below a certain bin in the U2, which allows them to state the 100 lumens minimum. However, I sure hope that the U2 will be a bit brighter than the L4/L5/L6. Otherwise, their ratings would be confusing for the customer, cause if one light is rated at 65 lumens and the other is rated at 100 lumens, you expect the latter to be brighter, no matter what the actual lumens values are.

Re: Heat dissipation of the U2 at 100+ lumens...ho

Don, being stuck on the stated lumen rating, is not exactly what is happening with me. I am fairly new with SF's conservative rating system. So when I see and hear from various people "inside" and outside of SureFire, that the high level output will be in excess of 100 lumens, that is what I go by. Any value over 100 is fine with me. In fact, as Mark2 wrote "<font color="red">I sure hope that the U2 will be a bit brighter than the L4/L5/L6. Otherwise, their ratings would be confusing for the customer, cause if one light is rated at 65 lumens and the other is rated at 100 lumens, you expect the latter to be brighter, no matter what the actual lumens values are</font>." I could not have said it better myself. His sentiments, are my sentiments. As long as the U2 is brighter than a production L4, L5, or L6, I will be satisfied.

You are correct that I grossly contradicted myself, making it appear to readers that when efficiency of a bin increases, then heat increases. The reality is that it runs cooler as the efficiency increases, so toasting marshmallows and heating rooms makes no sense. Chalk this up to trying to be entertaining and getting a laugh, and not a lack of knowledge of basic thermodynamics. Maybe it was even "temporary insanity", or the typing version of the condition known as "verbal diarrhea." Regardless, I stand corrected by you, and I thank you for your observation. I also agree with you that nobody will be using the U2 exclusively on high. If they need high output all of the time, then they would be buying some other one level light, and not a six level light.

If you state, and I believe you, that the "actual" output of a Luxeon bin will be 70% of Lumiled's rating, then I accept without reservation, any output that is 70% of the flux rating specified in the "W" bin. The "W" bin flux range is 147.7 lumens at a minimum, and 192 lumens at a maximum. Does anybody have a problem with a light output that equates to 70% of the minimum...103.39 lumens, or 70% of the maximum ...134.4 lumens? I didn't think so!

Don, your wife is becoming a real burden to you, to me, and to the CPF gang. Either she gives back the integrating sphere intact, peacefully, and without event, or you stop selling her your great modifications at cost!!! Thanks for the education. Remember this, "I'm young, I'll learn!" I will stumble many more times along the way, so keep an eye on me....

Yes kongfuchicken, I have nothing to worry about in the U2. All signs point to exceptional output with controlled heat dissipation.

Yes iddibhai, SF has a tendency to "grossly underrate" its lights. This is better than the other way around.

Re: Heat dissipation of the U2 at 100+ lumens...ho

[ QUOTE ]
luxlover said:
If you state, and I believe you, that the "actual" output of a Luxeon bin will be 70% of Lumiled's rating, then I accept without reservation, any output that is 70% of the flux rating specified in the "W" bin. The "W" bin flux range is 147.7 lumens at a minimum, and 192 lumens at a maximum. Does anybody have a problem with a light output that equates to 70% of the minimum...103.39 lumens, or 70% of the maximum ...134.4 lumens? I didn't think so!


[/ QUOTE ]

Now I understand perfectly. 70% is the losses through the glass and reflector. The L4/5/6 are probably using V bins (Ws were hard to get.. still are, for us), spec'ed at 113 lumens minimum. 70% = 79 lumens. Now given that there were probably still variations even with the binning and minimum bins, SF probably rated them at the minimum 'tactical' output figure of 65 lumens just to be safe and compensate for less-than-ideal conditions as binning is done under ideal conditions. This explains why most L4s are said to get at least 80. L5/L6s are probably somewhere in that region. They may be driven harder than the L4, too.

Stepping up to the W bin minimum for the new U2, and using your figures, explains why they can rate it at 100.

Re: Heat dissipation of the U2 at 100+ lumens...ho

Looking good KevinL. The U2 stork........anyday (week?) now! It is now clear to me that the only way to compare lights real time, is to eyeball them. I wonder if Don's lovely wife will ever give him back his integrating sphere?

Re: Heat dissipation of the U2 at 100+ lumens...ho

What really annoys me about Lumen ratings is that 100 Lumens output exactly can only be if each individual light featuring flat regulation is put in a rig and the output is then capped at 100 Lumens and locked.

100 Lumens could be an average meaning some lights are 65 and others are 135. My understanding is that the output regulation drives the LED regardless of the individual characteristics of the LED, and that LEDs differ in performance even from the same reel.

This talk of confusing the customer is kinda strange since SureFire are the most confusing flashlight company going. I've dedicated plenty of my time to helping people understand the huge ranges of products that SureFire offer.

The U2 sample I have has the same output in use to my eyes as the KL5 samples I have. They were most certainly produced some time apart.

There is only one way to know the Lumen outputs of your individual flashlight and that is to have it tested and rated by an accredited test lab. And then retested every 50 hours use to track any changes that may or may not develop.
Make sure you carry your flashlight's certificate of performance with you in your wallet.

Al

Re: Heat dissipation of the U2 at 100+ lumens...ho

Thanks, Al. I will certainly make sure that I make room in my "voluminous" wallet for the "flashlight's certificate of performance", right next to my American Express card. Remember what they say, "don't leave home without it." I won't. I might meet a flashaholic during a blackout in a subway car, and he will want to see if my U2 has the right stuff!!

SF has never, and will never use the "cap and lock method" to produce exactly 100 lumen U2s. Too much labor.

If your KL5 appears to be the same brightness as your U2 sample, then the KL5 must be much higher than 65 lumens, maybe even close to 100?

Although what you wrote is logical, I don't think that a Luxeon used in a U2 will ever be so deficient as to drop down to 65, but it may climb up to 135! SF is better than that!

Keep us well informed Sir Al.

Be good.......

Re: Heat dissipation of the U2 at 100+ lumens...ho

and from the man (pk)that built the lights, the answers to this question is:

1) the kl5 @ 65 lumens, is understated

2) the u2 is being driven a bit harder

led and and reflector config is the same; the theory of special heatsinking is invalid

Re: Heat dissipation of the U2 at 100+ lumens...ho

Odds are they just use a better-binned LuxV and underdrive it to achieve ~100 Lm output.

If mere mortals can now get their hands on W-bin LuxVs, imagine what a volume manufacturer willing to pay a premium can get?