im looking to expand my knowledge on LEDs and flashlights and i have a few questions about them that i hope to get answered by some of the more experienced vets and modders here,
1- what is the most efficent LED per lumens/ output? LED /XML/HID… ect- what is the least Efficient , incandescent ?
2- what one can pump out the most light/lumens before needing to go multi led to go brighter?
3- what is more efficient/ what is the differences between a multi led vs single LED? (besides obviously multi can be brighter)
4. Does power/lumen efficiently drop linear with increased brightness or does it at a point start getting much worse. ( ex…100 lumens for 100 hours—1000 lumens for 10,—or— 100 lumen for 100 hours , but 1000 for only 1hour ,)
5. any other useful info …
ive learned a decent amount so far but these were a few things i was unsure of still.
1. I'm not sure how HID compares, but the MT-G2 and XM-L2 are probably the most efficient in the current Cree lineup. That said, there is more to LED choice for flashlight use than just lumens/watt. Peak die intensity is also important if you want throw, so for some uses the highest lumen emitter isn't the best even if it is the most efficient in terms of lumens/watt.
2. The most lumens? The MT-G2. You can get an honest 4000 lumens out of one, and about 1800 lumens out of an XM-L2, but it won't be very efficient.
3. It is more efficient, in terms of lumens/watt, to have more LEDs run at lower currents, than less LEDs pushed harder.
4. No, the power (watts)/lumen relationship is not linear. At a certain point with each LED you start see the lumen curve flatten out significantly with increased amps.
5. I'll let others fill in here! I would check out flashlightwiki.com for a good general overview. There is also a good thread somewhere on BLF with an incredible compilation of information.
LED is definitely the most efficient of the technologies commonly available for flashlights. Laser-on-phosphor emitters have theoretical advantages, but I’m not sure they have any advantage in practice yet.
The Luminus SST-90 is pretty bright at 2700lm. Arrays of multiple LEDs on a single die can emit much more light, but those are usually too big to work well in flashlights. The Cree MT-G2 is an exception.
Multiple LEDs are more efficient at high outputs; LEDs are less efficient when driven harder.
I’m not sure what curve best describes LED efficiency, but it’s definitely not linear. LEDs are considerably more efficient at lower power levels.
Smaller emitters generate smaller hotspots and more focused light for longer range. That’s why some large, long-throw lights are using the XP-G2 rather than the more efficient and powerful XM-L2 or XP-L.