IS the SureFire L4 too hot to hold? Verdict: NO.

Thank you everyone for setting me straight, and please see my apology below (in the replies not in the text of this post.)


Hello all you SureFire L4 owners!

Please accept my appologies if I offended any of you with my thread "L4 is only a toy". *grin*

BUT at least TWO L4 owners have said that they could NOT hold onto their L4s for the entire run, Noah Monk being one of them. The Great Al, on the other hand, was able to put well over a dozen 123s through his L4 and his hands were fine.

I sincerely want to know what the story is here. Is the L4 too hot to hold? because I personally would have been mad as *** if I'd ordered one and then found that I couldn't count on it to be useful for the full run time. Many people have pointed out to me that "well, I don't need a light for that long" or "don't buy it" or "EDC is a package deal and the L4 is only one part of my EDC".

Yeah OK. I get it. The point is that I checked out the L4 on a bunch of web sites and read a review and also some CPF threads, and it was only because I just couldn't believe that there was no thermal issue and did a CPF search that I was made aware of how HOT the L4 can get, at least according to one person.

So the point is that if I had ordered the L4--me, for my needs--I would never have known of this (possible) drawback and I would have been very uncomfortably disappointed by my new light (possibly).

If someone says "I couldn't hold onto it for the full run!" I don't need to OWN an L4 in order to criticise it, and, YES, I'm going to be a wee bit in-your-face about it. Vendors and CPFers should mention this in and among all of their raves about the L4. I actually need a light to run on the order of an hour constant. Not very often, to be sure. Once or twice a year I would guess. And so I'd like to know the truth here.

So it all comes down to this question. IS the SureFire L4 too hot to hold? If it isn't then I'm impressed with it and I have three cheers to give for a quantum leap for LED lights. On the other hand, if it is, then it seems to me to be sort of misleading, in terms of how it is presented and advertised. And yes, even poorly designed, in that the thermal cooling is too little for the heat load.

So would all of you L4 owners help me out here? What is the story? I've done searches but have only mixed messages.

Re: IS the SureFire L4 too hot to hold?

I'm gonna wait for improvements in commercial 5 watt LS's before I plunk down the bucks. I have a modded Mag that cost me about $58 for a 5W. Impressive, but not to the point that I have to buy a SF L4. I'll stick with my E2e/KL1 for a while until things settle.
Rob

Re: IS the SureFire L4 too hot to hold?

I ran a L4 for 45 minutes straight Saturday night. At the end of the 45 minutes I changed the batteries and continued on with my work. At no time did the light seem too hot to hold.

I expected it to be hot but it was not. It was a comfotable "warm". The head of the light was very warm but did not burn me when I touched it.

There are two problems with the L4 though. Everyone who sees it and it's output of white light wants to ask all kinds of questions about it. And the other problem is that it is so lightweight I never remember which pocket I have it in /ubbthreads/images/graemlins/smile.gif

Re: IS the SureFire L4 too hot to hold?

Just save yourself some money and buy a G2.
$24.99.......65 Lumens

Re: IS the SureFire L4 too hot to hold?

I've never had my L4 on much longer than 10-15 minutes at a time and it never got "hot." It did get warm, but nowhere near burning-my-hands-and-I-have-to-put-it-down hot.

Like AZMAN stated, there are cheaper ways to get 60+ lumens, but if you want led and lightweight and don't mind shelling out the cash, see one of our highly rated sponsors (don't want to mention any names and get in trouble) /ubbthreads/images/graemlins/wink.gif

-Jason

Re: IS the SureFire L4 too hot to hold?

It doesn't get too hot to hold, but the warmer it gets the farther away from the head I go. Its actually think its actually cool that it gets hot, like most things high performance you sacrafice a little comfort for the benefits.

Re: IS the SureFire L4 too hot to hold?

I believe I put four sets of SF123A's through the L4 one set after the other and ran them all constant-on. I've done quite a few constant-on runtime tests too.

I don't think the L4 gets too hot to hold. Certainly not if you intend to use it.

Still, I believe that the vast majority will not require constant-on for more than 10 minutes or so at a time. Of course it's okay to be different from the vast majority.

Al

Re: IS the SureFire L4 too hot to hold?

The L4 does get very warm, and I might even term it hot, but for me, it's not so hot that I can't hold it. Certainly, if I left it on for 20-30 minutes straight and then hold it again, I'll probably be a little surprised at the heat, but that's to be expected from a 5Wer in this configuration.

The L4 doesn't have the beef the PM6 McModule has, but it is smaller, and its flexible configuration of batteries (from a single CR123 to a Copia to 2x CR123s to 3x CR123s to 2x-3x NiMHs) makes it pretty attractive...

Re: IS the SureFire L4 too hot to hold?

Hmmh - I´m still not sure where you are coming from posting things like the L4 being "sort of misleading, in terms of how it is presented and advertised. And yes, even poorly designed, in that the thermal cooling is too little for the heat load."

Seems like 99% of the actual L4 users say its no problem - and one or two people claiming it beeing to hot to hold .... the difference might be that if you put the light down for a runtime test and pick it up later it got hotter as your body doesn´t cool it anymore - holding it in your hand will give additonal mass. It **might** be that holding the L4 by the head would be unpleasant for an extended period but you still have the whole body to hold it and don´t need to hold it just by the head.

I think for pretty much all people who tried and don´t want to **proove** that the SF L4 is an overpriced piece of crap there won´t be an untolerable heat issue - but IF you really want to show that you will find some evidence you can nicely construct together to proove that as well.

And as was pointed out already we all know that the 5W emitters do create quite some heat when run at or slighty below max spec - and seeing the head heat up as fast shows that SF is doing a very good job in getting that heat AWAY from the die - which is a much better solution than keeping a cool head and having the die getting cooked - and which is what heatsinking is all about.

Klaus

Re: IS the SureFire L4 too hot to hold?

The head becomes too hot to hold after a while, but the temperature of the body is okay.

Re: IS the SureFire L4 too hot to hold?

I must be only one with girly-hands. I've tried this countless times on several L4's and they can not be held without being burnt. I guess is time for me to get one of those digital point-and-click tempature things.

Re: IS the SureFire L4 too hot to hold?

To me the L4 doesn't feel that much hotter than an E2 does after running for an equal amount of time.

Re: IS the SureFire L4 too hot to hold?

Please keep in mind that there is great variance in the sensitivity of each person's Sensory Nerves. Everyone is different. What is too hot to hold for one, is not to another.

In modern lights, the person's body is part of the heatsinking. This is certainly true in the current Arc LSes. If you set it down and leave it on, it will be hot after 15 minutes or so. However, if you hold it your hand for that time, it will only be warm. The body's circulatory system helps take the heat away from the light.

The fact that the flashlight's body heats up, proves that the heatsinking is working. You have to get the heat away from the emitter, or it will fry real quick.

So, for those that find the L4 too hot to hold, may actually have more to do with the sensitivity of their sensory nerves, than with the light itself.

Re: IS the SureFire L4 too hot to hold?

That means that cold hearted people like me are better at cooling the L4 because of the steeper thermal gradient from my hand to the core of my being.

Al /ubbthreads/images/graemlins/confused.gif

Re: IS the SureFire L4 too hot to hold?

What is everyone's definition of hot? To me, it's at what point does it become uncomfortable (vs. cool/warm), not at what point do I have to drop it as my flesh is searing. Just a personal choice, I guess. Intermittent use helps alot vs. straight 30+ minute burn. At uncomfortable, you start shifting hands without realizing it, or you simply become much more distracted and aware of the hot light in your hand. Neither is insurmountable; what are you willing to deal with for the advantages of the L4/PM6 McModule vs the variable discomfort and/or price? Other options may be better for you. They are for me, but that doesn't knock the L4/PM6 as a quality light.

Re: IS the SureFire L4 too hot to hold?

The points brought up about the body being a heat-sink and whether the light is held continuously are probably very relevant to this discussion. I did not hold my L4 continuously during the aforementioned battery test; It was unheld for several intervals of up to 10 or 15 min. Upon picking it up after this time, it was too hot for me to *comfortably* hold. I don't think it would have blistered me to keep holding it, but it was too hot for me to want to find out. I ran water over it to cool it down a couple of times so I could take it outside and shine it around at stuff.

Some backyard testing is perhaps in order? Someone out there with a nice temperature probe perhaps? Hold the light for 15 min .and measure. Let it rest on a thermally insulating surface (like styro) for the same amount of time and measure? Wonder what styro melts at? /ubbthreads/images/graemlins/grin.gif

Re: IS the SureFire L4 too hot to hold?

once again, as I stated 10 minutes ago in your other thread, I am the one who started the "Liquid-cooled"-thread. You may read my full comment there.
To summon it up: the head gets too hot to hold on prolonged constant on, the body does not at all, it just gets quite warm. AND as Al stated, you are safe to run as many sets of batteries through the light as you may possibly want. So ... an almost perfect little light! There should be good reqsons that all of us love the L4, shouldn`t there?
And you would never critisize a machine gun because the business end gets hot after a long fight ...
My thread was not intended to judge the L4, I apologize again for the misunderstanding (could have used any other 123 light), but to evaluate the possibilities and effectiveness of the human blood as a liquid cooling factor. It turned out that it may not be that effective after all ...
/ubbthreads/images/graemlins/grin.gif
bernhard

Re: IS the SureFire L4 too hot to hold?

My apologies to everyone. I'm sorry I misunderstood the thread and I'm sorry to have attacked the SF L4. I should have taken a different approach on this. I'm afraid I can be a hot head sometimes. It is something I am working on and I do make progress as time goes by, but I am still WAY too opinionated for my own good.

I applaud everyone involved for their maturity, and I will make a sincere effort to follow suit. I think that the CPF is just great. My brother has been telling me about it for years, and he was right.

Re: IS the SureFire L4 too hot to hold?

Of course, "hot" and esp. "too hot" are completely subjective. For me, the entire light (head + body) becomes unconfortably hot to hold after burning (unheld) for 10 min. or so. Heat generated by the head is conducted throughout the body of the lamp it seems (am I missing the Top Secret SF thermal gasket or something?) It seems a bit silly to say the "verdict is NO" when there are so many subjective variables involved. All that said, the L4 is my favorite light and I thoroughly enjoy using it - just glad I don't have to use it continuously!