Fenix L2D: Worth upgrading from Q4 to Q5?

I've had L2D Q4 for a while... great lite.

Very bright for the size. 135 Lumens.

I realize Q5 has 180 lumens, or 45 Lumens more.

Is it a good idea to upgrade? I want the brightest 2AA Lite, but not sure I will even see that extra 45 lumens.

When is the next generation of the LEDs will come out, with another quantum leap? I mean in the 200-300 lumen range?

I recently upgraded my L1D CE to an L1D Q5. The L1D Q5 is definitely brighter. You should upgrade your L2D Q4 to an L2D Q5. After all, it's only money.

etc said:

I've had L2D Q4 for a while... great lite.

Very bright for the size. 135 Lumens.

I realize Q5 has 180 lumens, or 45 Lumens more.

Is it a good idea to upgrade? I want the brightest 2AA Lite, but not sure I will even see that extra 45 lumens.

When is the next generation of the LEDs will come out, with another quantum leap? I mean in the 200-300 lumen range?

Click to expand...

Keep in mind binning is a range rather than a spot.

4sevens stated P3D drives its emitter at 0.8A*1 If it's driven at the same current on the L2D, you can expect that the LED will emit approximately 1.8 times the 0.35A spec.

From CREE:
0.35A specs:
Q4: 100-107
Q5: 107-114

At 0.8A drive and before thermal derating, you can expect 180-193 emitter lm from Q4 and 193-205 emitter lm

From what I can tell from the datasheet, the best case gain (if you have the bottom of the bin Q4 and you get the top of the bin Q5) is 14% measured and no gain in the worst case. Taking the ratio of mid-range of both, I'd say more likely gain is around 6.8% measured.

It is understood that our perceived brightness can be approximately represented by "square law".

In worst case, there is zero gain.
In likely case, there's sqrt(1.068) or 3.3% perceived gain
in best case, 6.8% perceived gain.

I would certain not buy a whole new light in a hope of gaining 3.3% of noticeable brightness.

*1 https://www.candlepowerforums.com/posts/2221090&postcount=32

etc said:

I've had L2D Q4 for a while... great lite.

Very bright for the size. 135 Lumens.

I realize Q5 has 180 lumens, or 45 Lumens more.

Is it a good idea to upgrade? I want the brightest 2AA Lite, but not sure I will even see that extra 45 lumens.

When is the next generation of the LEDs will come out, with another quantum leap? I mean in the 200-300 lumen range?

Click to expand...

I seriously doubt that you'll be able to tell any difference. I've upgraded a number of Cree lights, but from P4 or Q2 to Q5, which is worthwhile.

One other point -- a lot of the Q5 emitters I've seen aren't really more efficient than a Q4. They just have a higher forward voltage so they produce more light (but consume more power) at a given current. So if you "upgrade" to a Q5, you're likely to find that the run time decreases by just about the same fraction as the light output increases.

c_c

Thanks for putting things into proper perspective.

I think I will keep it until I either loose it, break it or give it away - no immediate plans to do any of it yet.

Curious_character said:

I seriously doubt that you'll be able to tell any difference. I've upgraded a number of Cree lights, but from P4 or Q2 to Q5, which is worthwhile.

One other point -- a lot of the Q5 emitters I've seen aren't really more efficient than a Q4. They just have a higher forward voltage so they produce more light (but consume more power) at a given current. So if you "upgrade" to a Q5, you're likely to find that the run time decreases by just about the same fraction as the light output increases.

c_c

Click to expand...

CREE doesn't rate the output by power consumption, but current, so efficiency is not part of the binning requirements.

CREE gives 3.3v typical and 3.9v max for [email protected]
3.7v typical at 1A, but no max spec given at 1A.

Do you really have L2D Q4? Or do you mean L2D P4? L2D Q4 should have more than 135 lumens on turbo.

I see that FENIXSTORE advertises stock heads.
Link https://www.fenix-store.com/index.php?cPath=27_41
None in stock at present though. I assume the heads are upgradeable?

I have L2D-CE, that I got last year from Fenix Store. It's whatever came before Q5 I presume.

The P4 came before the Q5(big difference between the P4 and Q4). There was also a special Q2 run but that was short lived.

From P4 to Q5, there should be around a 30% increase in output(noticeable, but not significant). If you think that is worth the work, then go for it.

I don't know about CE to Q5.

I have two examples of up-rated lights.

I have a LOD Q4 and a LOP SE(LUX) the difference is staggering!!!!

I have an older P1 LUX and a P2D Q5. Again the difference is staggering!!!

I have some pretty bright P4 lights, and P2D Q5 does not blow those out of the water.

But as an L1D Q5 I think I'd be pretty hard pressed to come up with a better EDC for MY needs.

I can't see where you'd need to upgrade to a Q5. I can completely understand WANTING to....

Sorry, I meant L2D-CE P4.

The original question should have said -

Fenix L2D: Worth upgrading from P4 to Q5?

P4 to Q5 is a whole letter worth of upgrade, which i think is the minimum when you want to upgrade the emittor.

Crenshaw

Crenshaw said:

P4 to Q5 is a whole letter worth of upgrade, which i think is the minimum when you want to upgrade the emittor.

Crenshaw

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I agree. I've done that upgrade to several lights. You get a 30 - 35% increase in light output, which is just about enough to barely notice.

c_c

I try to find someone to give my old light to...assuming it`s in good shape. Justifies getting the latest one out...I have a birthday coming up...

Badbeams3 said:

I try to find someone to give my old light to...assuming it`s in good shape. Justifies getting the latest one out...I have a birthday coming up...

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If it's in good shape, give it to a good friend or family member.

My LOD Q4 tells me there ain't nothing terribly wrong with Q4s.....

Badbeams3 said:

I try to find someone to give my old light to...assuming it`s in good shape. Justifies getting the latest one out...I have a birthday coming up...

Click to expand...

thats what happened to me LOD-CE....except someone offered to buy it from me...of course i was happy to sell it...

Crenshaw

I have both and the difference in brightness is not much.

Can you quantify the difference?