Sorry to ask what is probably a very noob question but I do not see this addressed anywhere here or online at large, and I am pretty new to modding/dealing with emitters. Can the new cree XHP50 3Vs be run on a boost driver powered by 1xaa? What kind of efficiency can I expect vs an emitter more commonly used in this configuration i.e. any popular 3v 3.5mm emitter such as the 519a or xpl.
I have plans to put an xhp50 behind a ridiculously tall reflector from kaidomain (20mmx33mm) but I want to be sure the emitter can be properly driven at these levels before committing to the parts purchase. Thanks for the help!
The 50.2 3V likes a good deal of power. 11 Amps if it can get it. Boosting an AA will be very difficult to get much out of this kind of emitter. It’s a quad core, or essentially 4 XPG2 if memory serves me correctly. Now, you might could boost to 1 XPG2, but don’t expect much from 4 on that tiny amount of power.
What kind of output are you looking for from the small light? Any particular reason you chose the 50.2?
Typically a square ratio on the reflector, 1:1, serves best for the most pleasing beam. This type of parabolic curve lends itself to our LED output patterns. A really tall for its width reflector, especially with a quad die emitter, is likely to be ringy and ugly in it’s beam profile.
You might like it, you might not, building it may teach you what to like and dislike.
I’ve got a couple of them and they’re running 5 to 6 Amps. They make a great flooder, but you can only get the 3V version in cold white 6500k and not with a high CRI. Use a orange peel reflector with them- I’ve tried smooth and it shows up their bad characteristics more.
If it was me, I’d go with a 519A or LH351D. I have got a 1 x AA boost driver running an XPG and that works well.
Intended output is less than 400 lumens. I chose the 50.2 because I thought larger emitters make for larger hotspots with reflectors, especially for the tall one I had in mind.
When you say square ratio, which dimensions do you mean?
I do have 2 519a’s on hand, just considering options on bigger dies.
The data sheet for an XHP50.3 (latest version) is here The graph at the bottom of page 22 gives LED current vs % of output for the 3V version up to 6 Amps. Bottom of page 7 gives flux output for given test currents. Top of page 21 gives current vs voltage curves. That will give you some stuff to mull over re the XHP50!
Realistically a AA boosted is probably going to not be suitable for it.
IIRC one of the zebralights could manage ~500 lumens from eneloop
It had like 4 parallel coils, I think.
So, it’s doable. Driver will be the challenge. Low CRI, cool-white XHP50 will help efficiency some.
Edit: the SC5 series (Example) could break 500 lumens with eneloop.
I just really like aa lights, I get peace of mind from having many lights that will usable in a scenario where li-ion charging may not be feasible. I chose the xhp50 simply because it’s got a huge die and I wanted a floody beam. What would be the floodiest emitter that works in the 1xaa voltage range? (1.2-1.5v)
LED’s are pretty much all 3V emitters, or more. The XM-L2 is essentially the same size die as the 50.2 with much lower demand.
The Cree datasheets show that at 700mA the 50.2 should make around 1000 lumens, with a forward Voltage in the 2.8V range. So it would produce considerably more light at low current than the XM-L2 (300ish at 700mA 2.7V) Makes sense given that the 50.2 has 4 dies vs the single larger die of the XM-L2.
Heat may be the bigger issue, given the small light you desire.
I wasnt aware the newer xmls even came in 3-4k and just read about the efficiency upgrades to the xml2, will definitely be ordering these! I have some older xml lights and while the beam patterns are great out of a reflector they were always very cool white.
