Disappointed in my L2D Q5

just got my L2d Q5 today and compared it to my L1d ce and L2d ce, I have a few extra single a and aa body tubes to switch heads around and the Q5 was the same brightness as my L1d ce and on the aa tube the L2d ce outshined the Q5, only advantage was the Q5 had better tint ie no blue fringing on the outer corona. anybody with the same experiences?

Does your L2D-CE Q5 have an orange peel reflector in it? If it does and your older LxD-CE's don't then that will explain why it doesn't really appear brighter.

Sure you didn't mix up the CE and Q5 heads?

Are you looking at it on a wall or outside? Often you relay cant see what a light can do unless you use it at a distance. And don't forget the Q5 is not a ton brighter than the ce.

If the Q5 has a high Vf, wouldn't a 1.5V AA or two AA's for 3V, not have enough voltage to power the Q5 at the same current the L2D-CE with a P4 would be drawing? So the Q5 maybe no brighter, or maybe less bright, than a lower binned Cree with a lower Vf.

I wouldn't use a Q5 in anything that isn't supplying at least 4V or better to the driver, unless the driver is designed to draw more current and increase the voltage so the Q5 can draw the desired amount of current.

If you get a Q5 with a low Vf than it may perform better.

Sorry if I'm not 100% on with this, just trying to put together what others have explained on CPF.

I did a comparison review of the Cree P4, Q2, Q5 and Rebel R080 & R100 Fenix heads on 2AA, 1AA and 1RCR here:
Fenix Rebel vs Cree: L1D/L1T/P2D OUTPUT, RUNTIMES, BEAMSHOTS!

As you'll see, there's little relative difference in overall output on 1AA. It's more noticeable on 2AA/RCR.

Is the Q5 the limited edition version they're offering?

If so my Dad bought one recently because he liked my L2DCE and his light is definately brighter.....

I had two Q5s and one regular CE at home before Christmas.
One of the Q5s was subjectively somewhat weaker than the CE whereas the other was roughly equal subjectively in output. (The Q5s were warmer in tint.) When put in a lightbox, the weaker one showed just lower output than the CE, and the other some 15 % higher output, where the bin differences should give a 30% improvement on average. All of the above was with L2D body and fresh and tested eneloops.

I didn't know quite what to do with it - the sample size was too small. Maybe I had a really good P4? But I suspect that Wade is on the right track, that we need to consider the Vf of the individual LED.

I proceeded to measure the current draw for the two Q5 and the P4 heads. The weaker Q5 head drew less current from the batteries, and when subjected to a runtime test, this was confirmed by correspondingly longer runtimes.

Could it be that the driver circuit of the L1/P2/L2 strives to output a given current, and is designed to achieve this within a certain window of Vf voltages? And, when confronted with a LED with high Vf, output is limited by the achievable voltage, rather than target current?

Cree doesn't bin by Vf or efficiency, and if the above situation is common, it really creates problems for manufacturers and retailers alike - the output you get is luck-of-the-draw. Fenix can't know without testing what the Vf will be of a given LED, thus they can't say whether the output of their "premium" light, which both cost more to produce and buy, will actually yield higher output than their vanilla variation. And of course this problem, unless dealt with, is dumped in the laps of the retailers who have the direct customer contact.

I asked the Fenix-store, where I had bought my lights, if my conjecture above was correct. Of course, they didn't answer.

(This is still assuming that everyone is honest in their dealing - that the lower performing parts isn't because someone in the long Cree-distributor-manufacturer-retailer chain decides to make an extra buck by fudging the bins. I've seen a lot of accusations fly around here regarding reputable vs non-reputable, chinese vs. american, and so on, because people get less than they expected and proceed to point the finger at someone.)

I had planned to buy a couple of L2D-Rebel100s to use as bike lights, due to their generally lower Vf and thus AA friendly nature. Now, with the recent recall, I just don't know what to do.

EntropyQ3 said:

I had planned to buy a couple of L2D-Rebel100s to use as bike lights, due to their generally lower Vf and thus AA friendly nature. Now, with the recent recall, I just don't know what to do.

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For a bike light I'd order the P3D, personally. More compact body, can use rechargeables, and brighter than the L2D. Seems like an instant win, to me.

The forward voltage should be irrelevant (within reason) if the light has a true constant current driver.

Stereodude said:

The forward voltage should be irrelevant (within reason) if the light has a true constant current driver.

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But the current is only half the equation (well, actually it's a third...)

There are also large perceived differences between smooth and orange peel reflectors, and with tint variations.

All of this reinforces the thought that lusting after the latest bin, and tearing out P4's to replace with Q5's and tearing out Q5's to replace with R2's is rather silly, and a rather pointless endeavor in the end.

Marduke said:

But the current is only half the equation (well, actually it's a third...)

There are also large perceived differences between smooth and orange peel reflectors, and with tint variations.

All of this reinforces the thought that lusting after the latest bin, and tearing out P4's to replace with Q5's and tearing out Q5's to replace with R2's is rather silly, and a rather pointless endeavor in the end.

Click to expand...

For the record, all three lights I tested had textured reflectors. That I perceived the Q5s as even lower output than subsequent lightbox testing showed, was probably due to tint.

EntropyQ3 said:

When put in a lightbox, the weaker one showed just lower output than the CE, and the other some 15 % higher output ...
I didn't know quite what to do with it

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I think I would have returned the low one for exchange and kept the brighter one. I think since they sell it as a premium special, it should be more "premium" than the CE version. Esp as there are Q2 and Q4 versions that should outperform the CE also.

specialk said:

just got my L2d Q5 today and compared it to my L1d ce and L2d ce, I have a few extra single a and aa body tubes to switch heads around and the Q5 was the same brightness as my L1d ce and on the aa tube the L2d ce outshined the Q5, only advantage was the Q5 had better tint ie no blue fringing on the outer corona. anybody with the same experiences?

Click to expand...

As it's been said before, with a high Vf Q5, there will be precious little difference between the lights on 1xAA battery.

Try the Q5 versus the P4 on the 2xAA tube, and you should see a decent difference.

However, keep in mind that the way our senses work is exponential, and thus any difference in intensity that's less than 2X will not necessarily be drastic.

Furthermore, both the P4 and Q5 bins have a range, with the minimum and maximum luminous flux, so the difference will range from (I think) about 15% to 30%, in the worst- and best-case scenarios, respectively. In the 1xAA configuration, given the Vf differences, the % change between the bins may be smaller still.

I saw a noticeable difference in brightness between my P4 and R100 on my L2D, and a very large difference between the P4 L2D and the T1, but then again, the T1 is rated at 225lm at emitter, and L2D at 135, which is a whopping 65% difference. But your mileage may vary.