Couple of noobacious questions re LEDs

Roogalator

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As will be readily apparent when you read these questions, I know precious little about electronics in general and LEDs in particular. Nevertheless...

1) Are there significant differences in the efficiency of various LEDs? By efficiency I mean the percentage of energy consumed that produces light versus the percentage consumed that produces heat.

2) Using the aforementioned definition of efficiency, are LEDs getting any more efficient with newer technologies?

3) Given the increasing energy density of batteries is the heat generation of LEDs going to be the limiting factor in flashlight output as technology advances?

Part of what drives my curiosity about this is that having to restrict run time to avoid overheating significantly limits a flashlight's usefulness to me, and I'm wondering if there are improvements on the way. I understand that flashlight design and choice of materials can mitigate heat buildup to a degree. But it seems as though there are hard limits on high output runtimes even with the best designs.
 

scout24

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Hi there, and welcome. I commented in another thread where similar questions were posted. Everything you ask has been relevant for the last 10 years. Difference is, the outputs we see today and are considered "Meh..." were the stuff of magic a few years ago. Today, you can have cells coasting along at comfortable draws putting out lumens we just dreamed of for runtimes we didn't think were possible. So yes to your questions, asked 5 years ago, and probably 5 years from now... :thumbsup: :welcome:
:grouphug:
 

ven

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Extra heat sinking and mass is your best friend for high output and sustaining it. If you need a high output 1000lm, then a light that is capable of 2-3000lm usually has the mass. If you need 2000+ then a lot of 4 cell lights have the mass(pop cans as well). If you start wanting over 4000lm for decent amount of times then again larger lights to help out, ambient temps will of course effect it, colder month=longer uses are an option.

Its great to have compact WOW lights that can kick out high out puts, but for much over 1m uses, they are of no use. If i am holding a pd35 or an rc40 in my hand...............i am using that hand:D
 

Roogalator

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First of all, thanks for the warm welcome. Glad to be here.

I can't imagine the mass you'd need to draw a practical amount of heat away from a 1000+ lumen light. Are we talking crew-served lights here? :) Perhaps the next evolution in high-output lights will be liquid cooling à la the Cray 2.

It's pretty amazing to me just how much heat a single LED and 1 CR123 can generate. I have a Streamlight ProTac 1L that uses a single CR123 that I used to carry clipped to my hip pocket. I stopped carrying it because the push button on the end cap kept getting activated by my phone, which I carry on my belt on the same side. Each time this happened I'd suddenly feel an intense heat in my pocket that felt like it was about to set my dangly bits on fire. :eek: Jeebus cripes that was nasty. Since that was the only practical spot to carry a medium size light I've since replaced the ProTac 1L with a twisty switch light so I don't become Chief Smoking Crotch.
 
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