3W headlamps?

In my ongoing quest to over-haul my household/automotive flashlights, I'd like to supplement my ray-o-vac headlamp with a brighter LED headlamp. Reading up on the Yukon HL and the Zenix, it was mentioned some time back that there are imminent 3W LS headlamps on the way?

I think a high powered led headlamp could get uncomfortably hot.

They'd better have some exotic cooling solution if they're going to be run at anything near maximum current.

I'll back up the comments regarding hot headlamps.

I have a cheap and dirty 5W design (step-up current regulator, continuous brightness control from 0W-5W depending on the input voltage). I have the Luxeon V Portable mounted on a CPU heat sink. A piece of PVC pipe protects the LED and Fraen (LP or larger) optics.

If run at 5W for more than a few minutes, the heat sink can reach 145F. Since I am a caver and it's mounted onto a helmet, this isn't really an issue. Most of the time it will be running at 1W anyway (maybe even less), so it will be cool. And, since cave temps run cooler, that will help keep the heatsink temp down too.

But, a 3-5W headlamp mounted directly on your forehead would have to have some really special heat management when being run at full power for more than a few minutes.

Scott

Does anybody know exactly how much heat is being emitted by these 3 watt LED's? How many watts of heat?

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ErickThakrar said:
Does anybody know exactly how much heat is being emitted by these 3 watt LED's? How many watts of heat?

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The exact answer to your question as asked is "No". Efficiency varies from LED to LED and power dissapated as heat also would of course depend upon the input power level. If operated at exactly 3W input power, approximately 2.7W is dissapated as heat.

Why not put a small fan on the heatsink- I thought about making a high power light that used forced air cooling it could be real small, and thermostatically controlled, but haven't got around to building one, maybe someday.

I've been wondering about passive liquid cooling myself. I remember reading about a low boiling-point liquid that was used (or proposed, anyway) to cool laptop CPUs several years ago - seems that a bit of thermodynamic ingenuity and some smart check valves could make that a reality for high-power LEDs.

I believe that they do something similar in laptop computers: using heat pipes.

Fans require power to run, so efficiency goes down. You might as well go with incandescent at that point.

Scott

if it's less than 3 watts, even a small computer heatsink can be used to dissipate that heat pretty handily. Or a tube could be machined with multiple flanges and would probably do a pretty decent job as well. Less than 3 watts of heat...Pfft. It's doable.

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ErickThakrar said:
Does anybody know exactly how much heat is being emitted by these 3 watt LED's? How many watts of heat?

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Very simple: 3 W .-) you can just ignore the little bit with goes out as light.

As I stated somewhere else, I do have Speleo Technics Nova headlamps.
Running these on 5W and moving around only a little bit keeps them at a reasobable temperature, that means the heatsink is not too hot to touch. When leaving it at the table at room temperature, the heatsink will reach more than 60°C in some 10 minutes (but it has not enough thermaical mass to cause any burns).
And the heatsink is not that large:

Perhaps the Matrix 2 (2AA), with a pair of Lithium AAs for in the car would do for you.