Fenix Turbo Mode

Yoda4561

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That looks like a rather nice fluke thermometer. They're very accurate (for this purpose) as long as you stay within their measurement area. Mine is a 8:1 ratio and I would imagine that one is even tighter. This means it measures a 1 inch area at 8 inches away a 2 inch area at 16 inches away, and so forth. If it was held less than 8 inches away from the light body it should be quite accurate.

*edit* Also I think it would be better if it was done at 0, 5, 15, 30, 60 minute intervals as opposed to every minute.

*edit 2* Just remembered, I did the boiling/lukewarm test just a little while ago after I read it here. They appear to freeze at roughly the same time though the boiling one had a thinner layer of ice on top than the lukewarm one did when I checked, I would imagine that as the freezing continued they would both be solid at nearly the same time. I recall learning about that question in high school physics class though I don't recall what the rationalle was for it nor the "correct" result. I need to put together an agitator to keep in the water to get a more definitive result.
 
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HKJ

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That looks like a rather nice fluke thermometer. They're very accurate (for this purpose) as long as you stay within their measurement area. Mine is a 8:1 ratio and I would imagine that one is even tighter. This means it measures a 1 inch area at 8 inches away a 2 inch area at 16 inches away, and so forth. If it was held less than 8 inches away from the light body it should be quite accurate.

Not a 1 inch area, but a circle with 1 inch diameter, and on my infrared Fluke meter your will not get below a 1 inch diameter, even if your go closer than 8 inch.

If the colors are accurate, it is not a Fluke, they use a more orange color and they also put their name on it.

One some of the better Fluke meters, your can also do a correction, depending on what your a measuring.
 

Yoda4561

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Well if you want to split hairs a 1 inch diameter circle measures an area smaller than 1 square inch, so there:thumbsup:
 

smvtsailor

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Just for thinking: What will freeze first when put into the freezer?
1. A cup full of hand-warm water,
or
2. A cup full of boiling water?
Hand warm. Less avg. kinetic energy/molecule to lose before able to freeze.

jirik_cz: I would also check that there was a thermal insulator (maybe a piece of styrofoam between the flashlight and the metal test tube clamp in both trials.
 

Mr.Urahara reloaded

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Hand warm. Less avg. kinetic energy/molecule to lose before able to freeze.



Nope, your answer sounds reasonable, but reality proofes it in "most" situations wrong.

Have a look here:
http://en.wikipedia.org/wiki/Mpemba

That's the effect and how it is called.



It would be interessting to see various Thermo-Scans for other ambient situations like 30C° and under humidity.
Then we could see some interesting stuff...

MfG Mr.Urahara
 

Yoda4561

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Okay, some quick numbers now that I have a metal bodied flashlight. Left the C2 with makloff M60 on for about 10-15 minutes, temps read 108f battery tube and 110f bezel. Putting it in my hand for about 2 minutes brought it to 106 battery tube and 108 bezel, not quite as stark as I had thought but I'll do some more longer tests starting with the light in and out of hand.
 

ToeMoss

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Hand warm. Less avg. kinetic energy/molecule to lose before able to freeze.



Nope, your answer sounds reasonable, but reality proofes it in "most" situations wrong.

Have a look here:
http://en.wikipedia.org/wiki/Mpemba

That's the effect and how it is called.


It would be interessting to see various Thermo-Scans for other ambient situations like 30C° and under humidity.
Then we could see some interesting stuff...

MfG Mr.Urahara

The problem with the Mpemba affect is that it only works if the containers are not covered. This violates the very premise of the argument that given equal volumes of water, the warmer sometimes freezes more rapidly. For the Mpemba affect to occur, water must evaporate from the container of warmer water thus making the volumes unequal.
 
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ToeMoss

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People in the past have verified it, and it is simple thermodynamics. Blood absorbs heat much more readily than air.


It also depends on the light. Larger lights will have a smaller (if any) window of difference. Small lights which heat up quickly will show a vastly different temp between both cases.

Depends on the temperature of the air and the heat transfer coefficient of the flashlight material. Also, unless you've had a really bad day, blood won't be in contact with the light, heat will have to conduct through flesh first.
 

Marduke

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Depends on the temperature of the air and the heat transfer coefficient of the flashlight material. Also, unless you've had a really bad day, blood won't be in contact with the light, heat will have to conduct through flesh first.

The lights in questions are made out of aluminum, with a coefficient of thermal conductivity of 237 W/(m*K). Air has a thermal conductivity of 0.025 W/(m*K). Guess what, flesh is made up mostly of.... water. Blood vessels lie just beneath the skin. If you don't believe me, cut your finger. The thermal conductivity of water is 0.6, 24x greater than air.

Some other useful items:
blood ~0.5
muscle ~0.56
human skin ~0.3, however when you are holding a warm light, your hand sweats, increasing the thermal conductivity with the addition of water
 

unique

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Question - I own a Fenix TK10. Lets say you leave it on for 10 minutes on turbo mode. Would you need to turn it off for it to 'cool' down, if so how long ???
 

defloyd77

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If you don't believe me, cut your finger.

OUCH!!! DAMN he's right! The L2T should be fine too right? I believe it's got the same emmiter as the non preium L2D (right?) but it's a wee bit brighter so maybe driven harder?
 

Marduke

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Ok, here is the graph. He used ni-mh batteries. Green is Fenix "cooled" by a hand and violet is light without cooling.

Can anyone point me on some tests in the past? I can't find any...

l2dtemperatureov4.png




How much degrees means "too hot to comfortably touch"? Temperature higher than your body temperature always seems "hot".


Here is some interesting data showing the benefits of cooling

https://www.candlepowerforums.com/threads/200492
 

Marduke

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Interesting results, but it is difficult to compare them with Fenix L2D, because Dereelight has almost double power draw.

The results are comparative, any high power LED aluminum bodied light would behave in a similar manner, just with different relative values.
 
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