So one thing that I think could become an issue, I see so many posts saying that a specific light gets too hot to hold very quickly and this is seen as a negative aspect of the light. From a thermodynamics point of view, this means that the design to transfer heat away from the LED’s is very efficient and the diodes can sustain turbo much longer, but larger mass will help to delay the raising temp of the body. If the designers of this light do too good of a job, I bet there will be many complaints that it gets too hot lol.
Regarding color to thermodynamics, black anodize is about the best you can get on the aluminum (closer to a black body - ideal radiator), but that only really affects the radiation heat transfer which is minimal compared the the convection (air) and conduction (hand).
BUT, this is really fun engineering/physics discussion that will never matter due the variances in manufacturing tolerances of the LED/battery/driver components, ambient air temp, user hand size, phase of the moon, etc. so please don’t let the shelf thickness issue become an issue!
Perhaps this was already discussed in this giant thread ( ), but who is going to distribute the lights? I see that Neal was on board, but since he left I was wondering if BG is still on board?
I am beginning to think we have a lot of the crazy drivers from Austin TX here on the forum, impatient and willing to crash people just to get moving again.
FWIW, the light I recently built from scratch cost me some $175 in materials and a little over 20 hours in labor, yes it makes almost double the lumens compared to the Q8, but the point really is if you try and do it yourself it’s going to get really expensive.
<—- Bowing to the Master’s and Queen codewriter’s here, standing by for the final product with zip for complaints about how it’s all going….
Also, FWIW, I’ve carried MILLIONs of pounds of construction materials, don’t really see where softball gives anyone much added strength although I guess a desk sitter can gain something from it. I worked with Ernest Dye when I was a young man. This dude could, at 67 years old, take my Dad’s belt in the middle with one hand and put Dad (around 148 pounds back then) to the ceiling… entirely one handed! 60 years old is no excuse for being unable to do much of anything. Just saying…
Teacher - radiation heat transfer occurs between two objects without the medium in between being involved, the heat transfer is between the two objects. For example you can feel heat from a campfire several feet away even if the air is cold. The sun can warm a surface even though there is vacuum of space. You could put a hot flashlight on Turbo and a cold light into a vacuum chamber with no air, and the hot light would heat the cold light even without any air to transfer the heat between the two (that would be convection).
I’d say Radiation is the easiest one, actually. The element in your oven, the element in an incandescent light bulb, the slight feeling of extra warmth when stepping out of a shadow into full, direct sunlight, our “color temperature” numbers - 3500K, 5000K, 6500K. Black body radiation is what all of these are about.
I was away for two days photographing a track meet, so my comments apply to conversation from a couple of days ago related to all the discussion of changes and the impatience, then Tom’s discussion on forearm strength training running the prototype battery tube tight over and over again.
I’ve built more than a few lights. And some all the way from scratch using bar stock materials. The latest is the Triple XHP-50.2 that makes a bit over 11,000 lumens. I started with a 3.17 pound piece of Tellurium Copper for the head. This works beautifully in final form, and the thick walled 6061 pipe for the battery tube can actually be felt sucking heat out of the copper head, into your hand! So the conversation about thermal dynamics of copper as compared to aluminum is related to this bit… I’ve found that copper absorbs the heat exponentially better than aluminum and aluminum works really well to disperse heat out to the air. Finned copper works well, especially when allowed to age darken instead of keeping it polished. This is all, of course, my findings when pushing a light to it’s limits.
All this costs though, and adding enough copper mass to really do the job gets expensive. The piece of Tellurium Copper I used for this light cost as much all by itself as the entire BLF Q8! ($42 actually, for the largest diameter piece of Te/Cu I could buy) I’m actually running almost exactly the same amperage through 3 of the 6V XHP-50.2’s as this Q8 runs through 4 of the 3V XP-L emitters (21A from 2 26650’s in series)
I am about to pull the driver and change the conservative MOSFET to an SIR404DP that should raise the bar on this light as it would the Q8 as well. Will let y’all know if or what difference I see in this change.
A flashlight that heats very quickly doesn’t always mean it’s very efficient at removing heat from the diode. Speed and efficiency are two different things.
For instance, you can create a flashlight with a 10w emitter that has very little mass and the whole thing will heat up quickly.
Take the same 10W emitter and put it in a flashlight that has a lot of mass and it will heat up more slowly.
These facts tell you very little about which diode is running cooler. There are a lot more factors involved. Such as where the extra mass is located, how well the diode is moving heat from itself to the star, from the star to the shelf, from the shelf to the body, etc…
Generally speaking, if you want longer turbo time you want more mass right under the diode. Big, thick, DTP copper star, big thick aluminum shelf with lots of good contact between the two. This will quickly pull heat away from the diode through conduction causing the diodes temperature to rise slowly.
As the flashlight body gets hotter the increasing difference or delta in temperature between the body and the ambiant air causes heat to more quickly get pulled out of the body through convection and radiation. This is where lots of surface area and dark colors help to shed heat from the body. Plus you have some conduction through your hand.
Ideally you want the flashlight body shedding heat at a rate that allows the diode temp to stabilize at a safe level.
As a general rule, heat moves more quickly and evenly through copper than it does through aluminum. This is why you see cpu heatsinks like this. The copper core heats up more evenly than an aluminum core therefore the aluminum fins furthest from the heat source (at the top) get just as much heat as the fins near the source. The copper mass also helps stabilize temps when the cpu does lots of small bursts of calculations. It’s like pulses of heat.
Anyway, I hope that helps folks get a better understanding of heat transfer.
I can’t tell how big this is JasonWW…… but I bet they were “fond of it”. $$$$$$$ …
Dale on meds, sorry for his pain.
Dale on meds bringing up a solved 2 to 3 day old “conversation” out of the blue…… Priceless.
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And yes sir J-Dub74… a very good conversation & discussion. :+1:
), but who is going to distribute the lights? I see that Neal was on board, but since he left I was wondering if BG is still on board?
