Liquid-cooled L4

ok guys ... remember my words of holding an L4 in my bare hand for the entire set of batteries constant on? to prove the value of the liquid cooling system (blood) of the human hand?
I spoke as a man and here I am presenting the results:
I am not a man at all. /ubbthreads/images/graemlins/icon15.gif
I didn't make it. This damned thing got too hot to hold even when gripping it tight from the beginning. OK ... it gets hot not as fast, but there comes the inevitable point when manhood gives in to reason or burned flesh.
Just wanted to let you know ...
I hope I'll be welcome in "The Club of feminine hands" consisting of Don and Darell ... /ubbthreads/images/graemlins/grin.gif

Oh ... I love my L4 even if I get burned sometimes. I even sleep with it every night ... /ubbthreads/images/graemlins/smile.gif

bernhard

Bernhard,

Your loss in the name of science has been our gain. Thank you! I will be entering a float on your behalf in the NY New Year's Day parade next year. It won't be a large float but anyone with macro capabilities on their cameras should be able to catch it in all its splendor.

The L4 was not designed for constant on, walk about applications.

- Don

Don,

You say the L4 was not designed for constant on. I was wondering where you read that. I can't seem to find much about it.

Thanks,

Chuck

Isn't there something liberating, and empowering about admitting that you're wrong, or that you've made a mistake?

I don't have a L4, but I can relate to your observations with a MadMax+ R2H. Holding it keeps it much cooler than when it is set down on a surface.

Chuck,

I didn't read it anywhere but received this information in verbal confirmation from PK. The laws of physics applies to all; a certain amount of mass and surface area are required for a comfortable steady state temperature resulting from a 5W Luxeon being driven at 620+ mA. The L4 does not meet these requirements nor was it intended to.

- Don

[ QUOTE ]
McGizmo said:
Chuck,

I didn't read it anywhere but received this information in verbal confirmation from PK. The laws of physics applies to all; a certain amount of mass and surface area are required for a comfortable steady state temperature resulting from a 5W Luxeon being driven at 620+ mA. The L4 does not meet these requirements nor was it intended to.

- Don

[/ QUOTE ]

Thanks, Don.

Chuck

[ QUOTE ]
McGizmo said:
Chuck,

I didn't read it anywhere but received this information in verbal confirmation from PK. The laws of physics applies to all; a certain amount of mass and surface area are required for a comfortable steady state temperature resulting from a 5W Luxeon being driven at 620+ mA. The L4 does not meet these requirements nor was it intended to.

- Don

[/ QUOTE ]

Does that mean that kiessling might succeed if he was to put on a few pounds?

Maybe they could use this as one of the elimination contests on the next installment of Survivor. /ubbthreads/images/graemlins/grin.gif

kiessling,

Try alternating the flashlight and a cold beer between hands. It improves both thermal management and courage. /ubbthreads/images/graemlins/grin.gif

Larry

/ubbthreads/images/graemlins/ooo.gif

It's the price you pay for a smaller package with the L4; smaller, brighter, better, but hotter...
/ubbthreads/images/graemlins/grin.gif

Although I wouldn't mind seeing a true "liquid-cooled" L4, in that the entire headpiece is encased in coolant and the LS wires itself are shielded properly, I'd imagine one wrong crack and that L4 would be drowning...
/ubbthreads/images/graemlins/icon15.gif

[ QUOTE ]
McGizmo said:
Chuck,

I didn't read it anywhere but received this information in verbal confirmation from PK. The laws of physics applies to all; a certain amount of mass and surface area are required for a comfortable steady state temperature resulting from a 5W Luxeon being driven at 620+ mA. The L4 does not meet these requirements nor was it intended to.

- Don

[/ QUOTE ]

Don,

Are we speaking only of human hand comfort or premature aging of the LED? If we could comfortably hold the L4 to battery depletion while wearing gloves would it then be within "non-destructive" design parameters?

Brightnorm

Brightnorm,

The hotter any LED runs, the shorter its half life. As a heavy coffee drinker, smoker and sun worshiper, I'm hardly the one to talk about premature aging. /ubbthreads/images/graemlins/icon15.gif If you want the LED to last forever, don't use it. /ubbthreads/images/graemlins/smile.gif Seriously, I am sure that a Luxeon would last longer in a cooler running environment than the KL4 provides if long play were the desired mode. As to actual hours of use, I haven't a clue. I believe one must decide for themselves the value of utility provided by the L4 in long play applications. I do suspect that the cost of batteries will overshadow the actual cost of the light by the time significant dimming of the LED is seen.

- Don

EDIT: What I don't know about thermodynamics fills the Library of Congress. However, I have seen posts about liquid cooling schemes and yet as I understand it you still need the phonons to be passed to the environment some how or the steady state temp level will still be the same whether the head were filled with air or liquid??!?!?

Is the whole body getting hot (on the flashlight!) or just the head?

I wonder if heatpipes work well in flashights? all that motion would be ideal to keep the fluid flowing.

The entire L4 gets hot [including the body].

Don, I agree just putting liquid in the light would not help [except possibly delaying the time to steady state]. The thermal energy needs to go someplace. If you've ever had the thermostat in your car lockup [in the closed position] you quickly learn that stagnant coolant is no better than no coolant.

FlashlightOCD, I have enough pounds on me to be the ideal candidate for this test, 100kg ... /ubbthreads/images/graemlins/frown.gif

Larry, /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif, I tried switching it between my two chubby hands, but once a certain temperature is achieved, it is just too hot! IMHO the great liquid cooling, the human blood, is not fast enough to take the heat away AND the bigger blood vessels with a greater capacity are located too deeply to be effective. when those would chime in, the surface of the skin would have been permanently altered by then, meaning denaturated, meaning burned.

AilSnail, the maximum heat is at the head of course, but after a while the whole flashlight gets warm. BUT you can still hold it at the body for a very long time, even if the head starts glowing red ... /ubbthreads/images/graemlins/smile.gif

Don, as always your thoughts are enlightening to us mere mortals /ubbthreads/images/graemlins/grin.gif. Thanx to my great advancement to science I am now able to tell you all: LED lights will get hot. /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/smile.gif

bernhard

The L4 makes for a great coffee warmer. Power it up for a few minutes, stick it into your cup of not-so-hot coffee (bezel first), then wait a few minutes and you're set.

How long of a continuous burn can you get before the L4 is uncomfortable to handle? Thinking of getting one.

[ QUOTE ]
FlashlightOCD said:
If you've ever had the thermostat in your car lockup [in the closed position] you quickly learn that stagnant coolant is no better than no coolant.

[/ QUOTE ]

In the case of a flashlight head, it would be worse. That's because any non-metallic liquid has a much lower thermal conductivity than solid metal. There will be no thermal convection, either, because the space is too small.

Humor aside, I actually did the same thing with my DIY "KL4." head(E2e/BB750/V3 5W- 1" dia, 1" long) It took an hour+ to run it down and I had to alternate hands. I probably wouldn't have been able to do it if it wasn't for the fact that I went through a few cans of beer in the process. A cold one will cool the "off hand" in seconds!
/ubbthreads/images/graemlins/icon3.gif (Flashaholic get-togethers could start getting wilder- "But officer, I was just cooling my flashlight." /ubbthreads/images/graemlins/grin.gif )

Larry

[ QUOTE ]
Phaserburn said:
How long of a continuous burn can you get before the L4 is uncomfortable to handle? Thinking of getting one.

[/ QUOTE ]

Phaser--It depends upon your personal heat tolerance. I find that the temp. rise is quite noticeable after only about a minute. After 5 minutes it is quite hot.
Somebody posted a time vs. temperature table on the L4 a couple of weeks ago. Try searching for it.---Marc