efficency per watt of new cree/seoul/rebel

[jasonsmaglites]

with cree cranking out the new bins every month or two now, i'm wondering exactly how much brighter are we getting per watt used.
i appreciate having a brighter flashlight as much as the next guy, but if it's just cause it's sucking more power from our batteries, we might as well have just up'ed the amperage!
how is seoul's efficency compared to cree right now, and where does the rebel100 stand. i'm talking with total watts here, not amps (gotta include that vf as a factor)

 

[LEDAdd1ct]

 

[daveman]

how is seoul's efficency compared to cree right now, and where does the rebel100 stand.

To figure out the efficiency, you have to first know what the output is. With the rebel 100, that's not difficult at all, as they're suppose to have exactly 100 lumens @ 350 ma. With the Seoul, you'll end up with about 30 different figures as its bin range is very large (the range between the least expected output and the peak output at a power level).

 

[Bearcat]

Yeah, I care more about efficiency and color than I do about brightness.

 

[Melven]

Yeah, I care more about efficiency and color than I do about brightness.

I also would be very interested to see which one is the most efficient.

 

[Gaffle]

Ok, I'm going to too.

 

[Sgt. LED]

It's like we are all at the movies or something!

 

[copperfox]

 

[Gunner12]

Scroll to the center/bottom of this page for a Cree bin/efficiency chart. Also check this, this, and this thread for some tested information.

 

[Sgt. LED]

Thanks for the links!

 

[Curious_character]

I've replaced lower binned Cree LEDs with Q5s in several lights. Interestingly, in lights having good current regulation, the run time of the Q5 seems to be less just about in proportion to its increased brightness. This indicates that the Q5 isn't any more efficient than the lower binned LEDs. At a given current it has (in my limited experience) a higher forward voltage, so it consumes more power. The increase in light output seems to be just about proportional to the increased power consumption. If this is true, you could get exactly the same result by increasing the current of a lower binned LED as you do by replacing it with a Q5 and keeping the current constant.

c_c

 

[Gunner12]

No problem Sgt. LED

Curious_character

If you got a good Cree Q5 with a lower Vf, you should notice a longer runtime.

The Q5 seems to be more prone to a higher Vf then the P4 Cree. Overall, the Cree Q5 is more efficient then the P4. In White LED lumen testing, JTR1963 got a lower Vf Q5 and it was more efficient then the P4 sample. i think it depends on the LED itself. If only Cree also binned Vf.

 

[yellow]

To figure out the efficiency, you have to first know what the output is. With the rebel 100, that's not difficult at all, as they're suppose to have exactly 100 lumens @ 350 ma. With the Seoul, you'll end up with about 30 different figures as its bin range is very large (the range between the least expected output and the peak output at a power level).

muhahaaa,
sure every rebel puts out 100 Lumen
Remeber the old Luxeon days: ONE lux bin covered some 3 to 4 bins of Cree because the range was soo large.
You think this has changed?

f.e. what exactly is a "Rebel 100"?
an "M" --> 90 min - 100 Max Lumen?
an "N" --> 100 min - 120 Max Lumen?
:thinking:
anyway the bin range seems to have greatly improved, I'm impressed
(to be honest, I am really impressed, that none of my bad feelings to the Rebels happened, that led is way better than I could ever imagine)

 

[Curious_character]

No problem Sgt. LED

Curious_character

If you got a good Cree Q5 with a lower Vf, you should notice a longer runtime.

I'll take your word for it. I'll have to modify my conjecture, then, to state that some Q5s (those with low Vf) are more efficient than lower binned LEDs and some aren't. All I've seen so far are in the second category. Where do you get Q5s with low Vf?

The Q5 seems to be more prone to a higher Vf then the P4 Cree.

LEDs are selected and binned for light output at a particular current, not a particular power input. It looks to me like some are ending up in the Q5 bin only because they happen to have a higher Vf and therefore consume more power for a given current. Some others might actually be more efficient.

Overall, the Cree Q5 is more efficient then the P4.

I'm sorry, I don't understand what you mean by "overall". Do you mean most of them are, or all of them are by some other criterion other than lumens per watt? If the former, what fraction are? If the latter, what criterion?

In White LED lumen testing, JTR1963 got a lower Vf Q5 and it was more efficient then the P4 sample. i think it depends on the LED itself. If only Cree also binned Vf.

I found JTR1962's posting where he gave the light output of Q5 binned LEDs he had (which have a lower Vf than ones I've seen). But I couldn't find the posting where he gave the output of ones from the P4 bin. Could you please give a link to this? Thanks!

c_c

 

[Gunner12]

The Q5 Vf seems to be the luck of the draw, like the tint.

Overall as in the average of all the Q5's lumen per watt. You might be right in assuming that some LEDs are placed in the Q5 category because of their higher consumption and not because of their improved efficiency.

Corrected P4 charts, Q5 charts.