Okay, so I was thinking of ways of keeping the temps down on these lights, when an idea came to me which I haven’t seen anyone try yet.
What if you got a thermal pad 
And cut a hole in the middle for the dome/reflector?
You could stick one of these on a driver also with two pin prick holes for the wires.
Anyone think this is an idea worth trying?
Thermal pads aren’t a heat solution. All they do is conduct heat between two imperfect surfaces. You still need a heatsink on top of those. And they don’t work nearly as well as thermal compound due to their thickness.
Also here you can see a similar application and what actually happens. A large heatsink goes over the pads to radiate the heat out.
Well, that’s perfect for the job I’m currently on then at least.
I am modding a ultrafire w-878 which has a metal lid with a hole in it that screws into the pill above the LED which is around 1m above it.
I didn’t know they were essentially an alternative for thermal paste in situations where you can’t get a nice connection so I guess I have learnt something today. I had previously only seem them on a few chips on the underside of the xbox 360 mobo.
A more radical alternative is to use a thermoelectric cooler, also known as a Peltier diode or solid state refrigerator, to pump the heat away from the led or driver. These consume power and generate their own heat, but keep the device cool. They are used in camping refrigerators and to cool sensing elements and heat critical electronics. This may be easier to do than liquid cooling.
TECs aren’t practical in a flashlight with the extra heat they produce & power needed.
TECs are horribly inefficient. http://en.wikipedia.org/wiki/Thermoelectric_cooling#Performance
Silicone pads have been used in the flashlight world for quite a long time, mostly with drivers where the hot parts can't be placed in direct contact with the outer body due to the PCB layout, as a non-permanent alternative to potting. A thick thermal pad has really bad performance when compared to the parts in close contact with a thin layer of conventional thermal paste, it's only better than nothing.
Yes, with possible unusual exceptions.
A Peltier has failed in many applications, and it will not work in a flashlight for sure. The flashlight doesn’t disperse heat fast enough to even deem the peltier useful.
In computer applications thermal pads are also useless as they are thick and doesn’t transfer heat as well as a thermal paste. A thermal pad is used mainly when the gap between the cpu and cooler is larger than 1mm. If you can get the cpu and cooler to touch against each other then thermal paste is the way to go.
What about on a driver circuit? Surely it’s better than nothing? You end up with a much larger surface area for the heat to be distributed than just the chips themselves.
Don’t be too sure about that 
Small lights not feasible I agree. But large ones J)
There are two parts to this, firstly getting heat away from the emitters quickly and peltiers will do that very well. The second and much more difficult part is how to get rid of the heat from the peltier, heat pipes finned sinks with annular fans may prove sufficient.
I have already been down the road of a BTU Shocker with MT-G2s and the heat issues are enormous. So much so that without active cooling it is a non starter for me, as I want the thing to be on for more than a few seconds at a time. I have done a few experiments with peltiers and the results have been encouraging. Very difficult and costly I grant but I think a very possible solution to the heat issues.
I’ve been experimenting with peltiers also, but not in flashlights and so far it doesn’t look like a good future for them.
I wish you luck though, since it would be nice to find a way to maximize the cooling for the flashlights! innovation has to start somewhere
A flashlight with a car heater core hung off the side and several lead acid batteries for power (or a gas generator?) really doesn't sound very practical to me.
It seems most of people don't understand peltier's purpose:to achieve temperature lower than ambient.But,side effect is a lot of extra heat,so without extra passive/active cooling you wouldn't do absolutely anything,just make it worse,no matter how efficient peltier is.
Some (bad) drivers get so hot they'll unsolder their own wires. The correct solution is probably to just not use those drivers. Good drivers will run cooler than the pill and adding any thermal crap will at best just not affect them at all.
I deleted my post before I saw your reply when I realized that I had asked an unnecessary question.
The question was whether drivers really need additional heat sinking.
Drivers often need heat sinking of some sort but practically speaking the led(s) generate far more heat so the farther away the driver is from the LEDs the longer it will take for heat saturation to occur in the driver. If the driver mcu is being used to monitor the heat then in order to protect the LEDs(as with Taskled drivers)the closer it needs to be. Many of us >) seem more concerned with prolonging maximum output than protecting LEDs that get swapped out anyway.
It’s probably been discussed before but what about using it in reverse to add more runtime to the battery? I know they’re terribly inefficient but they seem to do a pretty good job in those candle powered LED lanterns.
They're just as inefficient in reverse too. It gets worse when you're keeping the hot thing as cool as possible like needs to be done with a LED, since the greater the differential between hot & cold sides of the TEC the greater the voltage generated. It would end up with the LED running hotter than without the TEC, and only making at best a few milliamps, which is a drop in the very large bucket compared to what's used in powering the LED. edit: It's likely the drop in LED efficiency would more than offset anything generated by the TEC.
They do work in certain applications but this isn't one of them. As generators they can be useful in things like attached to the incredibly hot exhaust/catalyst on an engine, where all that heat would otherwise just be dumped to atmosphere, and attaching TECs to the outside of a pipe doesn't have any negative impacts on the exhaust flow which could have a negative impact on engine performance.
Does a peltier make more heat than it removes ? If the goal is to cool the star or the pill , and the hot side transfers heat to the body, why care about more heat going to the body, if the pill stays cooler. I am asking because I do not know. I am not supporting either side here.
Yes, they make incredible amounts of waste heat in the process of cooling the thing you want to cool. Those low efficiency numbers mean something like 10 units of waste heat that have to be dispersed somewhere for every 1 unit of heat you remove from the thing you're cooling. And the cooler you can keep the hot side, the more heat they can remove from the cold side. So, not a thing for a handheld flashlight.