Arc LSL - Is it too hot?

I own an Arc LSHF and recently, just purchased the Arc LSL-S. I left my LSL switched on and left it on my table yesterday. When I picked it up after 5 minutes, it was really hot. Not too hot to bear but I think it's too hot to handle. It gets kind of uncomfortable.
My LSHF however, doesn't get that hot easily.
Is there problem with my LSL?

Did you also test your LSHF by switching it on and leaving it on your table for 5 minutes? A light held in the hand will draw heat away from the light into your hand (human cooling system at work). Leaving it on the table builds up the heat very quickly.

Yes I did.
I left my LSHF on the table for more than 5 minutes. It wasn't as hot as my LSL... that's for sure.
By the way, my room temperature here is around 34 Degree C.

could it be the different efficiency of the LEDs coming into play here?

I'm curious how hot should a LED light get compared to an incandescent flashlight?
It can't be as hot as a surefire. Even the regular p60 bulb gets hot.
I have a first run LS and it never gets too hot. I will measure the temp with my temp gun next time.
Does anyone out there have any measurements?

Nexro, I don't know how you can live in a room at 34*C. I have an LSL and an LSH-P. I have not noticed much of a difference in temp, but indoor temperatures where I live are kept around 20*C. I do notice the warmth from both lights after using them for awhile.

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BlindTiger said:
I'm curious how hot should a LED light get compared to an incandescent flashlight?
It can't be as hot as a surefire. Even the regular p60 bulb gets hot.
I have a first run LS and it never gets too hot. I will measure the temp with my temp gun next time.
Does anyone out there have any measurements?

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BlindTiger,

this is exactly one of my next projects, since I'm always concerned about heating and heat dissipation and other issues. So, while I don't have time vs. temp graphs yet I CAN tell you that the Arc LS, or at least the two I have used (one LSL, one LSH) most certainly DO get as hot, and even hotter than a 2x123 SF light w/P61 run constant on. I have run my P61 for an hour straight, through three battery changes, and it was, if anything, less hot than an Arc LS run constant on, which I have done on numerous occasions.

Most of the wasted power of an incan gets radiated out the front of the light in the form of Infra Red. i.e. it has a "hot" beam, a beam you can FEEL with your skin. In contrast an LED has a "cool" beam, one that I don't think you could feel on your skin, but the trade off is that the wasted power turns up as heat in the die and must be drawn away to the head and dissipated there.

The heat build up in my Arcs has never been an issue; never TOO hot to hold or work with, only something I most certainly notice, and something that I don't enjoy. Also, as has been pointed out, in some cases a light left on and unheld gets hotter than one being held, although mileages vary on this depending on ambient temperature and air flow and so on.

As for differences between LEDs, I can say that yes, each one will generate a different amount of heat, although all of the LS's will fall within a certain range, which in my limited experience is not that broad.

FWIW.

I don't know why, but my LSL is certainly much hotter than my LSH. Also, the whole thing gets hot... not only the LED part but the battery part too!
My LSH only gets 'warm'.

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nexro said:
Yes I did.
I left my LSHF on the table for more than 5 minutes. It wasn't as hot as my LSL... that's for sure.
By the way, my room temperature here is around 34 Degree C.

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DANG! 34 degrees C = 93.2 degrees F. Some like it hot, I guess, or perhaps nexro lives next to the engine room of a large ocean going ship, or near the heat exchangers of a Nuclear Power Plant, or perhaps in the tropics?

Too hot for me at any rate.

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js said:
In contrast an LED has a "cool" beam, one that I don't think you could feel on your skin,FWIW.

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I can definately feel the beam of my LSH-S on my lips when the light is about 5 cm (around two inches) away from them.

Guess my LS really is a "second" because I could never use it as a handwarmer. Yes, it does get warm but not radiating heat like a SF. Again, I'm just curious because we sometimes over hype our products.
Would it get hot enough to bubble up the lexan lens like a SF?
Speaking about hot, how bout the bottom of any laptop?

There is no heat in the beam of a LED. All the heat generated goes straight into the emitter, which is why heatsinking is such a big issue with high powered LED lights.

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BlindTiger said:
Guess my LS really is a "second" because I could never use it as a handwarmer. Yes, it does get warm but not radiating heat like a SF. Again, I'm just curious because we sometimes over hype our products.
Would it get hot enough to bubble up the lexan lens like a SF?
Speaking about hot, how bout the bottom of any laptop?

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BlindTiger,

There are two very different issues here! One is heat radiating out along with the visible light of the beam. The other is heat disipating out into the head/body of the light. The first is what melts and bubbles the lexan lenses of the SF w/ P61. It's the IR radiation that does it!

The second is what makes the BODY of the light hot to the touch. As long as you have either an LED or a glass lens, the first issue is a non-issue, but this second issue--heating up of the metal body of the light--can sometimes be serious. dano melted the pedestal of his MC w/ WA 1160 light setup, and one person that I know of finds that the SureFire L4 run constant on is too hot for him to hold comfortably. I have never used an L4 so I have no idea how hot it gets, but anyway, you get the point: the only heat "radiating" from a SF is the IR radiation in the beam. I personally would not describe the body as "radiating" heat, at least in the case of the 2x123 lights with either LOLA or HOLA's, and no LED light in existence will bubble it's lexan lens. Not at the center anyway--maybe at the edges from the hot metal but at that point your LED would be toast. /ubbthreads/images/graemlins/smile.gif

maybe your battery is shorting in the case, i've test run a LSL (2nd) on a 2 x 123 setup and its still cool after 5 minutes ( and darn bright i might add - been testing for 1 month so far )

rob

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robstarr-lite said:
maybe your battery is shorting in the case, i've test run a LSL (2nd) on a 2 x 123 setup and its still cool after 5 minutes ( and darn bright i might add - been testing for 1 month so far )

rob

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WOW! This is interesting, in light of a comment Peter made regarding people buying the 2x123 Arc LS3 power packs and using them on their Arc LSL/H's: he said you would probably blow the light, and even if you didn't, running this setup voids your warranty. The idea some people had was to possibly put a Pila rechargeable in there in place of the 2x123 lithiums. Anyway, glad to hear your LS is standing up to this out of spec drive.

yes i am aware of what could happen and not recommending anyone else to do this not trying to steal this thread but been surprised with this result having tricked a number of 2nds & grey kits.....

...the battery case shorting is real.... i make it a habit to inspect the battery case insulation whenever changing ( nail polish to fix ). [ happens quite a bit with the AA rechargeables which makes sense with all the handling ]

rob

I have checked the battery's case and the insulating material is intact. No tear whatsoever.
The light still gets quite how if I leave it on while on my desk. However, while holding it, it only gets a bit warm.
Guess this has to do with the LSL?
I am very certain my LSHF is much cooler, both on the desk and in my hands /ubbthreads/images/graemlins/smile.gif

robstarr-lite,
Thanks for the tip. I will make sure I always inspect all my lights' battery once in a while /ubbthreads/images/graemlins/smile.gif

One more thing, do you guys replace the CR123A once your LS goes into moon mode or use it until the battery gets flat out?