LED efficiency

[Dovii]

I have an older LED flashlight with a Cree Q3-WC, it is around 5-6 years old, now will I get better run times on the same brightness with using newer LEDS ?

 

[jorn]

If you buy a new light with the same levels, yes. If you swap the led in your old light to a new one, no. But you get more otput with a led swap.

 

[Scourie]

The Q3 produced up to 100lm's at 350ma and max drive of 1000ma. For comparison the XP-G3 S5 can produce up to 182lm's at 350ma and be driven at up to 2000ma.

 

[zs&tas]

The question was a little vague, basically if you modified your current light the runtime is set by the driver, you will get the same current more brightness. If you buy a new light you can search for the brightness levels you require you will gain runtime .

 

[Dovii]

if I double the current, do I double the lumen output ?

The Q3 produced up to 100lm's at 350ma and max drive of 1000ma. For comparison the XP-G3 S5 can produce up to 182lm's at 350ma and be driven at up to 2000ma.

 

[TheBelgian]

The question was a little vague, basically if you modified your current light the runtime is set by the driver, you will get the same current more brightness. If you buy a new light you can search for the brightness levels you require you will gain runtime .

You would gain some runtime because newer, more efficient leds are not only brighter at the same current, they also have a lower forward voltage. Thus the total consumed power will decrease.
Replacing your LED with the most efficient equivalent (the XP-E2 R4) would almost double the output, but also increase the runtimes 13%.

 

[TheBelgian]

if I double the current, do I double the lumen output ?

Very roughly speaking: yes.
More correctly speaking, for double the current it'll probably be about 90% brighter instead of the full 100%.
But the voltage will increase, more than doubling the consumed power.
And unless you've got really good cooling, the extra heat is going to mean a hotter, less efficient LED, lowering the brightness some.
So make that: double the current will consume 120% more power for 80% more light.
DISCLAIMER: these are very rough estimates, but they should paint a general picture.