Those efficacies are at 350mA (only 139 lumens at the emitter for the R5) so they would be less at anything useful like 1000mA. The new XM series is supposed to be 160 lumens per watt and Cree has a press release saying they have attained 200 lumens/watt in their lab with non-production LED's.
Especially as the XMs can be driven at 2A for silly lumens. Just happily awaiting my 23 minute runtime (With 5000mAh cells) SST-90 light now estimated as up to 3K lumens. Efficient no, bright definitely. At the theoretical maximum this would be a 12,000 lumen light!
The theoretical limit is about 400 lumens/watt so hopefully we'll be seeing a lot more light for the same current for some years yet. I believe Nichia has some 5mm LEDs that can do over 200 lumens/watt but then they only use fractions of a watt at best so aren't the sort of things I'm looking for - they aren't about to give me the sun in my hands.
Awesome review, that sucker is bright. As for the tailcap is it the standard size like all the other lights we have.....if you need some i can send you a couple of black and orange textured ones.
If you're interested in light output at high currents, you can calculate the theoretical lumen output at various currents for most of the LEDs from the spec sheets. Someone at DX did it http://www.dealextreme.com/forums/Forums.dx/Forum.-209~threadid.530221
I tried a few myself and results seem the same.
BTW the XM-L is is supposed to put out 750 lumens at 2A! (Yes this isn't that far from the highest binned MC-E or P7 at the max spec 2.8A.) Although I would take a guess this is the top bound of the highest bin at release, i.e. the actual bin will be something like 680-750 lumens at 2A (still 2A for 680-750 lumens vs 2.8A for 800-900/753-858 lumens). If you haven't seen it there's now also a slide from Cree's presentation at Light Fair on the XM-L that may be of interest http://ledinside.com/News_cree_LED_20100513
Thanks for posting that, made a good read def.
It sounds like the XM LEDs won't really be suitable for flashlight use. Pity...
Oooops, this review escaped me until now. Sorry about that brted! Wonderful high-quality review as usual. Now frontpage'd and sticky'd. I also played with physics and changed the date you published the review so that it goes to the top of the frontpage. ;)
Thanks for making it a sticky!
As a follow-up, I did replace the driver with the NANJG AK47, which I reviewed here:
http://budgetlightforum.cz.cc/node/310
The bottom line is that the new driver doesn't ever draw 1.4A like the original did (sometimes), but it is much better regulated and maintains that 1.05A draw down to about 3.8V. Also I like the 3 modes. I also replaced the smooth black tailcap with an orange one with some texture. So it was pretty easy and cheap to get rid of a few of the cons about this light and it is still very bright.
I got the 5 mode version of this from KD. There's only 1 board inside with what looks to be 1 mcu chip, and the current draw (>2a at start) implies it's just direct drive with a mode circuit. The soldering is also pretty crap (driver fell out), and the thermal compound never vulcanized properly or something so the emitter pcb falls out too if you take the reflector off. The 502b is pretty nice, though.
So.... get the 1 mode from dx and avoid the 5 mode KD if you really want to take the chance.
Sorry to hear about yours. I hope you were able to get your fixed up (or return it). After KD's early R5 drop-ins seemed to have the LED well behind the bottom of the reflector, I was afraid to get one from them. Is/was your LED partially blocked by the reflector?
I still really like my 502B with the 3-mode NANJG AK-47 driver in it. I also replaced the smooth black switch cover with a textured orange one and I think it looks great.
Is/was your LED partially blocked by the reflector?
It kind of looks like it, but not really. It's a proper xp-* reflector. The spot is well formed so that's hardly the problem with it....
I do quite like the 502. Kind of has that industrial feel of socialism to it :)
Ultrafire WF-502B Cree XM-L U2 And UltraFire WF-502B Cree XM-L T6 ,
so than Cree XP-G R5. what better.
I imagine the 5 mode drill is same as my WF501s. Don’t have my 502 yet, but I don’t think I like clips. Maybe just remove it and replace the screws with a little CA to seal. Shorten the screws? Otherwise the light looks good for 11 bucks with a long delivery wait.
Jaxon
Hi Guys,
do u know if this Light is original or no? The price is good
Many thanks
Ale
Have a pleasant time here at this friendly forum, robbynaish!
Looks just like mine. Also looks like a good deal!
@raccoon city
Thans for your welcome message
Thanks, i will buy in that shop… hoping yr comparison is right 
Alex
My opinion of banggood is it's a spammish POS foul looking ebay type trash site . Everything they sell is same old same old ebay trash ..If you want to know what are the worst lights ever made they are showcased Right here on Banggoods 4 flashlight pages .Every single one of them should be avoided and would probably yeild a nice purplish bad binned emitter,bad heatsinks ,nasty PWM,cheap andozationetc.... it's obvious that they are just scraping the bottom of the barrel ..A shop purely price driven .I see nothing they sell as redeeming in any way .I'd avoid them at all costs and assume everything they sell is a fake / a second or something being dumped .
Spam site
Hi Poaz,
im sad read so…. at least in hobby models thing their products are very good, and even if something is failed, they change without they ask u send it back (t happened to me), i had to send them a small video showing smt was no ok.
On NG http://www.rcgroups.com many users bought from banggood many different models and are originals.
So u suggest to buy from manafont?
Many thanks
Ale