That is a good price for the DTP board for a Luxeon V.
I got my led4power 4040 boards in (thanks!) and did test the Luxeon V on this dedicated board, I will try to crush the numbers this weekend and post the result. In short: I found hardly a performance gain (very slightly though), but the ease of reflow makes this board well worth using. I expect the reliability to be higher as well.
I did one not so great mod with the Luxeon V, I put one in a Olight S15 (AA) flashlight and hoped that the low Vf, and thus less voltage difference to boost, would increase the current and output compared to the stock XM-L2. But it is apparently not that simple, instead, I found just 180 lumen with the Luxeon V, compared to the ~250 lumen of the stock XM-L2. It must be something measured different in the electronics that makes it get less current.
The VG10 with the direct driver and Luxeon V is still one h*ll of a light, great beam, great tint and with a half-drained 30Q it still puts out 1700 lumen (at still 6.5A current, 75lm/W flashlight efficiency).
I’m not totally impressed by the efficiency, I measure 2.4A at the tail, an Eneloop runs at 2.4A at around 1.25V, so that is 3W of power and thus 60lm/W. For a light that needs boosting from a NiMh cell that may be alright actually, but at least some of my flashlights with li-ion cells go over 100lm/W.
After reading this I would like to repeat my question:
“Wouldn’t this LED be a good choice for FET driven 3x AA lights (e. g. Convoy X3, powered by Eneloop cells)?”
I am thinking of a bright flashlight with NiMh cells for my son.
According to HKJs’ review Eneloop 1900 mAh delivers a current of 5A at 1.1 V, which (with 3 cells in series = 3.3V ) meets djozzs’ numbers pretty well (5A at 3.25 V for 1800 lumens).
Where do I lose voltage? 3 cells in series sum up to about 3.3V at 5 amps, where the LED is pretty efficient. Eneloops should be good for this current, HKJ tested them up to 10 amps with a max. temperature raise of about 20 °C. Even the capacity of the cell doesn’t decrease much at higher currents.
Coincidentally I was able to do a quick check on 3 Eneloops in series because a few years ago I made a 3xAA carrier with phosfor-bronze springs and Omten switch (using Oshpark boards) for a project that I never finished. Pushed against the Luxeon V-modded VG-10 head I checked the output on 3 fully charged Eneloops, 30 seconds after switch-on I measured 1400 OTF lumen, that is about 1600 led-lumen, which should be about 4.2 amps (measuring the amps directly is not as quick as this was).
Of course upon draining the batteries the output goes down considerably (though not dramatically because the voltage curve of the Luxeon V is relatively steep), but this at least shows that a 3xNiMh set-up should work well enough to make a flashlight with very decent output.
Today I tried the Luxeon V 4000K 70CRI in my black Emisar D4 (see the WDYMT thread). The output and beam were very rewarding, but although it still looks alright, the tint is better in the VG10. I can’t say for sure but I expect it is a reflector vs TIR thing, the hotspot from the TIR is more yellow, and the rosy appearance in the VG10 beam is not obvious in the TIR beam.
Also, while playing with both flashlights, it looks like the tint is better (more red in the tint) at high current when the led runs on the FET than at low current when the led runs on the 7135.
The black D4 with LuxeonV’s runs pretty efficient even on highest setting. On a freshly charged 30Q I measured 15A for the first minute. A 30Q at 15A has a voltage of about 3.7V in that minute, so the power use is 55.5W. If you take the output at 12 seconds, 4620lm, the flashlight efficiency is 85 lm/W, which is rather good. This is not surprising because it is a quad, each led receives just 3.75A in which region the LuxeonV is still quite efficient (guess what, it is even well within specs :party: ).
The same story goes for XP-L(2)’s btw, and even in somewhat less extend for XP-G2 and 219C.
This implies for me that a triple channel driver in a multi-emitter light like the D4, or the FW3A, is a nice luxury and should certainly be aimed for, but the huge efficiency boost in the middle modes that some folks promise does not quite happen, it will not be more than an unnoticable 10 or so percent.
Lights that have a complete battery available per led (single led single li-ion, or i.e. the Q8) drive the led on highest setting very close to the inefficient max, in that case a triple channel will have some merit.
