quick heatsink question
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SmurfTacular
Enlightened
I would assume ideally you would want fins in order to achieve a greater surface area. But I don't think there is any room for that in most flashlights. In fact the only time I've seen fins on any flashlight and the heatsinks on the ballasts on spotlights 50w or more. I' not really an expert though.
VidPro
Flashlight Enthusiast
fins to do what?
fins are to improve transfer to the air (or water or whatever), without any air moving around in there they wont be to helpfull.
the "fin" on my flashlights are the case on the outside that is exposed to the air (or transfers heat through my hand).
so speaking only logically, you want heat conduction to the outside metal stuff to be as large and fast as possible, then fins on the outside (if needed) where it will increase the transfer of the heat to the air.
if the fins are on the inside, then you want air to go through them somehow, like a chimney hole, a fan, or large air pockets ?? which still wont work, or something??
i would never use Fining, inside a CLOSED container ON the item that was transferring the heat to the outside, because that would be less transfer of heat to the outside, not like we want to transfer the heat to the batteries except in special circumstances.
i would gladly put in finning inside, when/if i can get the air going across them from-to the outside.
if its a plastic flashlight or headlight well then fin something
, but then allow some air passages too.
fins are to improve transfer to the air (or water or whatever), without any air moving around in there they wont be to helpfull.
the "fin" on my flashlights are the case on the outside that is exposed to the air (or transfers heat through my hand).
so speaking only logically, you want heat conduction to the outside metal stuff to be as large and fast as possible, then fins on the outside (if needed) where it will increase the transfer of the heat to the air.
if the fins are on the inside, then you want air to go through them somehow, like a chimney hole, a fan, or large air pockets ?? which still wont work, or something??
i would never use Fining, inside a CLOSED container ON the item that was transferring the heat to the outside, because that would be less transfer of heat to the outside, not like we want to transfer the heat to the batteries except in special circumstances.
i would gladly put in finning inside, when/if i can get the air going across them from-to the outside.
if its a plastic flashlight or headlight well then fin something
, but then allow some air passages too.
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I am building a flashlight and run time is not really a concern, I found a 40mm computer fan that only takes 140ma to run. So If I fin my heatsink and mount my driver board on one side and led's on the other and provide intake and exhaust holes it seems like it should work pretty good.
berry580
Flashlight Enthusiast
fins to do what?
fins are to improve transfer to the air (or water or whatever), without any air moving around in there they wont be to helpfull.
the "fin" on my flashlights are the case on the outside that is exposed to the air (or transfers heat through my hand).
so speaking only logically, you want heat conduction to the outside metal stuff to be as large and fast as possible, then fins on the outside (if needed) where it will increase the transfer of the heat to the air.
if the fins are on the inside, then you want air to go through them somehow, like a chimney hole, a fan, or large air pockets ?? which still wont work, or something??
i would never use Fining, inside a CLOSED container ON the item that was transferring the heat to the outside, because that would be less transfer of heat to the outside, not like we want to transfer the heat to the batteries except in special circumstances.
i would gladly put in finning inside, when/if i can get the air going across them from-to the outside.
if its a plastic flashlight or headlight well then fin something
+1
AnAppleSnail
Flashlight Enthusiast
You won't be going far wrong using a processor heatsink with that fan mounted on, actually.
VidPro
Flashlight Enthusiast
what situation is that?
in this particular thread you have provided no application information? dont even know how many leds your using of what type at what power or anything? what case is it going in?
is there a thread you started on the project your working on?
is it this? So if i was driving 7 xp-g r5 at 1 amp
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Russel
Enlightened
The flashlights that I have modified, I machined a heat sink to conduct heat from the emitter to the outside of the flashlight case. If I were to use fins to increase the effective heat dissipation area it would be on the outside of the flashlight.
It seems to me that internal forced air cooling of a flashlight would be impractical and unnecessary unless you are talking about extreme power levels.
Would you be so kind as to describe the flashlight electronics and casing that you have in mind?
Sorry, that is the thread. 7 xp-g with blue shark driver, and 3x 18650 protected cells. It is going in polished copper tubing.
So I just did not know if using a fan would be helpful or if I should leave it solid core?
This light is not going to be practical or used in long periods of time. I like to build them from scratch, more of an expensive art project I guess you could say.
So I just did not know if using a fan would be helpful or if I should leave it solid core?
This light is not going to be practical or used in long periods of time. I like to build them from scratch, more of an expensive art project I guess you could say.
imho, there were a "useful" use of a fan, when that light will be used for long durations, freely mounted somewhere.
If remaining hand-held, the blood inside the hand (+ moving air) will give noticeable cooling
and when considering the size of the air channel and the fan: think of how much more-than-usual thermal mass could be put into the light (leaving it still smaller than the fan version and waterproof as additional bonus)
When You plan that thing as "burst" light - less than 10 mins of use at a time - then just put a thick thermal/mounting plate inside.
If remaining hand-held, the blood inside the hand (+ moving air) will give noticeable cooling
and when considering the size of the air channel and the fan: think of how much more-than-usual thermal mass could be put into the light (leaving it still smaller than the fan version and waterproof as additional bonus)
When You plan that thing as "burst" light - less than 10 mins of use at a time - then just put a thick thermal/mounting plate inside.
Cool I will forget the fan idea. I already have a huge heat sink(50mm round by 5.5 inches long). The heat sink is not a super tight sqeeze, it fits in not to hard not to soft. So should I put some heat past between the heat sink and the tube or should I just count on the contact between the two?
VidPro
Flashlight Enthusiast
as long as you get the heat off the led items themselves quickly, to keep them very cool, heat transfer at a Larger slower transfer area can be slower across without much problems.
meaning:
at the led itself you have ~1mm (emitter)
to ~10mm (emitter base)
to ~200mm (any PCB) square of area,
at a heat sync to case transfer location you might have ~10cm Square area for the heat transfer,
so although it is slower heat transfer across it, transfer is still happening fast enough.
on the other hand the better your transfer there , whatever you have to do to accomplish it, the lower the temperature of the led itself, the lower the temperature at the led the longer it would last. (even if you go so far as to fin and fan)
living here in california where outside temps can be very high, we certannly increase the rate of transfer and conduction of heat whenever/wherever possible.
as long as you can clean it up, work with it, still be able to re-mod it or repair it later, do it.
meaning:
at the led itself you have ~1mm (emitter)
to ~10mm (emitter base)
to ~200mm (any PCB) square of area,
at a heat sync to case transfer location you might have ~10cm Square area for the heat transfer,
so although it is slower heat transfer across it, transfer is still happening fast enough.
on the other hand the better your transfer there , whatever you have to do to accomplish it, the lower the temperature of the led itself, the lower the temperature at the led the longer it would last. (even if you go so far as to fin and fan)
living here in california where outside temps can be very high, we certannly increase the rate of transfer and conduction of heat whenever/wherever possible.
as long as you can clean it up, work with it, still be able to re-mod it or repair it later, do it.
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