disagree
Copper is 69% MORE heat conductive than Aluminum.
see here
Titanium is 95% LESS heat conductive than Copper
Holding a flashlight in your hand moves MORE heat away from the body of the light, than freestanding the light in still air.
So when using a Titanium/Copper D4, the BEST way to keep it cool is to hold the Copper part in your hand. Holding the Titanium part won’t do much.
and btw, the reverse polarity protection of the D4 does not work. IF you put a battery in backwards it WILL heat up AND overdischarge (to prevent that, be sure to test turning on the light when you insert a battery)
video courtesy of RobertB
Conductivity is the travel of heat in the material itself and is not a bottleneck with CU and AL in flashlights, what interest us is the heat transfer coeficient through convection, it’s better with AL than CU, anodized AL is better than non anodized AL (17% advantage at 0 air speed, so only convection moves air), oxidized CU is better than non oxidized CU among other factors because the oxidized one has a larger surface area than polished one.
I dont quite understand your post
are you agreeing that copper is more heat conductive than aluminum?
you seem to be focused on convection, if by that you mean heat transfer to AIR, that is not the primary cooling mode for a flashlight. Holding it in the Hand moves heat away by conduction, much more than still (no fan) air convection. Or maybe I misunderstand your terminology.
In any case, yes, the copper head will get a lot hotter than the Ti body.
1) from led (primary heat source) to surface of flashlight ==> thermal conductivity of materials
2) Dissipation of heat from surface of flashlight to surrounding, whether it is air, or physical contact (hand). ==> radiation, convection and conduction.
I’m not a machinist but have been told that is a resounding YES.
For instance I once sent off a bunch of my Titanium items to be beadblasted my an industrial machinist whom I meet on CPF. It was the 1st time he worked with the material and -> upon blasting the Ti hot sparks/embers were sent all over his shop Apparently that’s one of Ti’s machining properties. Supposedly it machines quite differently than stainless steel. (But yeah, no first hand experience here. Perhaps the machinists on here can chime in.)
I agree the copper alloy called Brass is much lower conductivity than aluminum, but, I don’t think the D4 Ti is using a low conductivity alloy. If you have facts, please share, otherwise, your generalization may not apply. afaict, the copper head IS more conductive than Aluminum, since its Copper, not Brass
I didn’t quite see what you were arguing before you edited your post, now my answer seems off.
Seems reasonable to think that most of the heat transfer goes though the skin rather than the air granted one don’t wear gloves, but the useful surface area of exchange with the skin on the copper pill whatever way you hold the flashlight is teeny tiny compared to the one you would have holding the AL one with the full body being a vessel for heat, and the whole heat being concentrated on those fins would surely be quickly incomfortable to touch.
I’m still not sure what we are arguing, semantics, physics ?
I was disagreeing when someone(s) suggested that aluminum moves more heat than copper (maybe I misunderstood, and the idea was meant to be that the aluminum D4 moves more heat than the Ti/Cu, which I do agree is possible).
I disagree that the copper used in the D4 has low conductivity
another perspective on the TiCuD4 heat management:
The Ti Body with the Copper Head is a major safety improvement. It allows the user to fire turbo without fear of burning their hand. Just hold the Ti Body, don’t touch the hot head, let the light do its thermal regulation thing.
Since there is thermal regulation, the choice of metal is possibly less significant to the overall heat management of the D4.
On a side note, i was replying to your last message (#67) and went back to read one sentence and the whole answer was completely changed again, this is very confusing for the sake of the train of though going though the thread, i agree (i don’t see the safety point though) with your post #67 22:46 UTC time 7 of january 2018 version
The most common “pure” copper used for machining is TeCu, barely loses any proprieties with 93% conductivity of actual pure copper and it is well over aluminum alloys like T6061-T6 that are only 40%
These go hand in hand though.
Silver is the best both thermal and electrical.
Copper is second, i think aluminium is third. (correct me if i’m wrong).
Benefits of Aluminium is light weight and easy machining, and the fact that you can give it a strong(er) ceramic layer by anodizing.
Funny as I’ve never thought about this before (edit: probably forgot about it). I have been told in high school that the electrons in metals are the primary carriers of thermal heat for conduction, and the electrons are covalent electrons. And covalent electrons should obviously result in good electrical conductivity.
They never told me that, or maybe i wasn’t paying attention.
Makes sense.
I did know heat through metals behave somewhat similar to electricity.
A good example is a thermostat with a rather thin copper wire to the much larger ‘sensor’, like you find in gas heaters.
Heat/temperature is basically kinetic energy (= energy) of the masses, i.e. protons, neutrons and electrons. The protons and neutrons are stuck in their places, whereas electrons they can go wherever they feel like going. So although electrons have very small mass compared to protons and neutrons, it is their extreme mobility that makes metals good thermal/electrical conductors.
I was talking about electrical conductivity, in that case is applicable.
In any case the amount of theories are astonishing for a 2cm piece of material.
This is a super tiny body in 18350 that because of the titanium electrical resistance should not even output as much power as the
aluminum versions, thus the heat produced by the LEDs will be less, all theoretical.
Not sure exactly as how much the very low electrical conductivity of titanium alloy will impact current as the walls are not that thin to start with so the resistance cannot that high, still.
Apparently that’s one of Ti’s machining properties. Supposedly it machines quite differently than stainless steel. (But yeah, no first hand experience here. Perhaps the machinists on here can chime in.)
