Questions about 200 lumen claim on Fenix P3D Q5

This forums has at least a few experts on them, so I've got questions.

The dealer's claim is that its got 200 lumens leaving the lens,
"What's more, the Fenix P3D throws an awesome 200 lumens beam"*3 but I find that a little hard to believe from reading the datasheet for LED. Is this a measured value?


On datasheet, it reads "Cree maintains a tolerance of +/- 7% on flux" and power measurements and all the output is at 25C TJ.*2

The binning sheet says 107-117 lumen for Q5 *1. I'm assuming I can apply the 7% tolerance and 25C TJ given in datasheet.

If I assume 80% Light output ratio for the optics(this is a PURE assumption, could be way too high), the LED has to put out 250 lumens. If I assume the LED has an output at the mean of the range min and max, which is [email protected]. Since realistically, junction temperature is going to be 50-75C, to get 250 lumens, the current would have to be what it takes to get 278 lumen at TJ of 25C.

The output derating factor for temperature I used is 0.9, based on the datasheet graph.

Cree's graph rates the output at 0.35A as 100%, so to get 248% output relative to this point, it would have to be driven beyond 1A, which is the highest point the graph goes to, it seems that you have to drive at 1.2-1.3A to get 278 lumens, but that's going outside the allowed specs.

Is my estimate of Light Output Ratio for the optics way too high?
Are they driving the LEDs out of specs?
Am I estimating the LED's internal temperature junction too high?

HOW are they getting 200 Lumens OUT THE LENS?

1
Cree® XLamp® XR-E and XR-C LED Binning & Labeling. Durham: Cree, 2007.
http://www.cree.com/products/pdf/XLamp7090XR-E_B&L.pdf

2
Cree® XLamp® XR-E LED Datasheet. Durham: Cree, 2007.
http://www.cree.com/products/pdf/XLamp7090XR-E.pdf
3

"Fenix Digital P3D Black Premium Q5." Fenix-Store.Com. 13 Oct. 2007. 9 Nov. 2007 <https://www.fenix-store.com/product_info.php?products_id=358&osCsid=7e7e24ce0a7d40a0f53755bc085188a7>.

I think the P3D drives the Cree Q5 at 1A, which should result in 250-256 emitter lumens.

WadeF said:

I think the P3D drives the Cree Q5 at 1A, which should result in 250-256 emitter lumens.

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I'll have to go check the graph again and calculate again to see where you got that, but did you apply the thermal derating factor?

funny
i have the P2d and the P3D both in Q5
using the same kinda batteries it seems the smaller p2d is brighter

Handlobraesing said:

I'll have to go check the graph again and calculate again to see where you got that, but did you apply the thermal derating factor?

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That's just a figure I've heard many manufactures claim for a Q5 being driven at that current. How do you know your thermal derating factor is correct? Sounds offly hot for a well heat sinked emitter.

Shagbd said:

funny
i have the P2d and the P3D both in Q5
using the same kinda batteries it seems the smaller p2d is brighter

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Did you take any meter readings, or just going by your eyes? A tint difference could make one appear brighter than the other to your eyes. Are they both OP reflectors?

First, you need to read up on how these LEDs actually perform, outside their datasheet values.

https://www.candlepowerforums.com/threads/172379

A bare Q4 XR-E will produce around 240 lumens at 1A. This is real output, actually measured from an XR-E running, with a Tj of around 55-60C. So you can expect a Q5 to output around 250ish or so. You can then derate from there appropriately for the optics. So with 1A in, 200 lumens out the front isn't entirely unreasonable. It's even more easily possible with the XR-E driven at more than 1A.

The P3D Q5 puts out very close to 200 lumens out the front. Chevrofreak got around 195 on his output meter which is as exact as anything we have right now.

WadeF said:

Did you take any meter readings, or just going by your eyes? A tint difference could make one appear brighter than the other to your eyes. Are they both OP reflectors?

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Just my eyes...

whats interesting is only the P2Ds seem to do the turbo flash when you have it on regular mode

I have 3 P3ds , all Q5s and none of them do the turbo flash..
sorta OT, but just a note

Graph from chevrofreak. The initial drop said to be caused by heat built-up... But it does start at over 200 lumens!

Holy Crap! My P3DR100 is way down there in output. I love these Q5's, but your almost new lights loose a little of their luster next to them. Thanks for the graph Chrvrofreak!

WildChild said:

Graph from chevrofreak. The initial drop said to be caused by heat built-up... But it does start at over 200 lumens!

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Whats the best way to get his runtime graphs? the link i have does not seem to have this latest one. the link i have been using is http://lights.chevrofreak.com/runtimes/

How can i see his newest?

Hey the graph would suggest the new Q5 has no flash for power draining warning? the other graph you see the fluctuations, but not on the Q5

evan9162 said:

First, you need to read up on how these LEDs actually perform, outside their datasheet values.

https://www.candlepowerforums.com/threads/172379


A bare Q4 XR-E will produce around 240 lumens at 1A. This is real output, actually measured from an XR-E running, with a Tj of around 55-60C.

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The data sheet does show you how it performs up to 1A.
If you got the top of the distribution curve Q4, 220% * 107lm @350mA * 0.925 temperature factor gives you 218 and if the measurement was made with anything but properly calibrated integrating sphere, a reading of 240 isn't entirely out of reason.

If you used a commerically made one what's the spec accuracy? If it's home made, I would give +/- 25% as a likely accuracy.

So you can expect a Q5 to output around 250ish or so. You can then derate from there appropriately for the optics. So with 1A in, 200 lumens out the front isn't entirely unreasonable. It's even more easily possible with the XR-E driven at more than 1A.

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The Q4 is rated at 350mA & 25°C TJ 100-107lm
Q5 at 107-114

So, they're not mutually exclusively. I'm not sure what bin they throw it in when the LED is in the 107 region. Since they don't give you the normal distribution of Q5, let's ASSUME the median is the same as the midrange, which is 110.5 lm. Datasheet shows the output at 1A is ~220% of 350mA rated output at 25°C*.925 thermal derate, so 225lm at the LED seems like a reasonable value. Now, to get their claim of "200 lm beam", the optics LOR would have to be 89% (and thats still assuming TJ won't go above ~60°C and the If is 1.0A)

Does 89% optical efficiency sound right for a flashlight reflector?

If you used a commerically made one what's the spec accuracy? If it's home made, I would give +/- 25% as a likely accuracy.

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I know you love to quote specs and accuracy, but I've calibrated my setup to several known sources, and can achieve within 5% accuracy when measuring bare LEDs. So don't go pulling that here.

evan9162 said:

I know you love to quote specs and accuracy, but I've calibrated my setup to several known sources, and can achieve within 5% accuracy when measuring bare LEDs. So don't go pulling that here.

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Details are overwhelming.

Handlobraesing said:

Details are overwhelming.

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I'm overwhelmed by the details of your +/-25%
You know thats an actual range of 50%?

Where did you pull that out of?

David,

Does the P3D CE Premium Q5 have a different driver than the P3D Q5 mod? I was wondering about the lumen output differences.

Nake said:

David,

Does the P3D CE Premium Q5 have a different driver than the P3D Q5 mod? I was wondering about the lumen output differences.

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The difference in runtime can be caused by a different LED Vf.

techwg said:

Hey the graph would suggest the new Q5 has no flash for power draining warning? the other graph you see the fluctuations, but not on the Q5

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Yes, they removed the low battery warning flash.

what made them remove the low battery flash? I guess just because its better to have a dimming light at the end of its regulation, than a flickering one. But then if your eyes dont catch it, even quicker to get a kaboom because your not on the ball about what status of the draining cells is