New Fenix Headband -- 440 lumens on your head!

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jankj

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For some time ago I had GU10 based Cree replacement bulb named "Solarox". In about 15 minutes it got very warm and in 30 minutes it was uncomfortably hot to touch. At this point I used to cool down the bulb by just grabbing the heatsink for a while and the temperature decreased significally in just under minute. I confirmed the temperature drop with other hand so that possible skin temperature raise didn't matter.

Flashlight manufacturers also know this and that's why they usually warn about leaving light on max power unattended(= out of your hands).

For cooling via your hand to take place the surface temperature must be above your skin temperature. (If not, the light is cooling your hand, not the other way around). If this effect is to be any effective, the light should be quite warm to hold. If it doesn't feel warm to hold, your hand is not cooling it. As your experiment confirms, the hand is able to cool a WARM bulb/flashlight.

Another aspect when holding the light is that the light will be MOVING. There are few circumstances where you will hold the light absolutely still when in your hand. Even though your level of activity may be low, the increase in airflow versus a light lying still on a table is substantial.
 
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Stromberg

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If it doesn't feel warm to hold, your hand is not cooling it. As your experiment confirms, the hand is able to cool a WARM bulb/flashlight.

Yes, I know this. My point being that hand is quite effective cooling element as long as the heat source exceeds the surface/blood temperature of the hand.

Any Cal.
"It does not necessarily mean that the LED is too hot"

Of course not, but if headlamp is used long times with only minor movement(for example electrician making connections in almost stand still situation) one can hardly say that heatsinking is fuss over nothing.
 
Jagge

Jagge

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if headlamp is used long times with only minor movement(for example electrician making connections in almost stand still situation) one can hardly say that heatsinking is fuss over nothing.

For me it's difficult to believe anyone would like to use high mode, 200+ lumens with tight spot in those situations. Most likely low mode is used and heatsink re-design would actually be fuss over nothing for this use case. But I get your point, I guess there may be some rare cases where someone really needs to use fenix style 200 lumen tight spot headlamp on high mode for long periods indoors without moving, but I am not sure is it a valid reason to say jankj's suggestion can't be done without a serious heatsink re-design.

Similar unscrew-the-head-of-your-fenix-and-screw-it-on-your-bike-handlebar would not be bad idea. More burning time for biking use with a bigger battery pack.
 
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Stromberg

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For me it's difficult to believe anyone would like to use high mode, 200+ lumens with tight spot in those situations

Me too, but I was actually thinking my old Tikka XP with diffuser installed, because it really could use 200+ lumens..

but I am not sure is it a valid reason to say jankj's suggestion can't be done without a serious heatsink re-design.

I never said it can't be done - in fact I said it was very good idea. I said only my opinion that heatsinking re-design is(or can be) necessary. Then again I might be wrong in this case. We'll just have to wait and see when 200lm headlamps really break into the 60-80$ market.
 
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Jagge

Jagge

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So true, I completely forgot the duffuser use. Some may like to use high with diffuser, even leave it somewhere indoooes on high.

This is one of advantages diy people have. One can build a ideal custom lamp one purpose, like ultra lightweight headlamplamp without much heatsink for running below freezing temperatures. Commercial ones are always some kind of compromises.
 
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Bobpuvel

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It may be really weird having this but AT LEAST they made it a three strap design! I will probably buy this just to see how it does... for 25 bucks! how could ya go wrong?(rhetorical question haha)
 

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