I was fortunate to be successful in winning an item off the instantkill of Wallbuys. The FandyFire STL-V2 I have draws around 1.9A at the tail. I may measure more with better leads but I suspect the 1.9A is about right. This was with Sanyo 2600mAh protected and similar figures were measured with a pair of 3400 Protected Panasonic 18650’s. I did expect more and when I compare the light output to a well driven C8 it’s comparable. It may be producing 1000 Lumen or thereabouts.
That's about 3.8A towards the 3 emitters,, that should be more than 1000lumens.
2 x 18650 is about 8Volts so at 1.9A at the tailcap that amounts to about 15W of which may be 12W finds it’s way to the LEDS. A T6 driven with 4W probably puts out about 400 Lumen, so 3 x 400 = 1200 lumen which sounds reasonable. Visually doesn’t seem too much brighter than my C8’s. Still a very good value torch but I was expecting more.
I have at the tail:
1,85A (2xnoname unprotected)
1,56A (2x3400 Panasonic unprotected)
How to compare it with these results?
Ok - just popped in 2 fresh KeepPower 3100's in my FF STL-V2, measured 2.42A at the tail and here's the results:
Lumens: 1,632 at start, 1,604 at 30 secs, throw: 18.7 kcd
I think these #'s are pretty good, though I bought mine last year and hasn't gotten much use and is totally stock. Really want to mod it up though - better driver, U3 emitters on copper I'm thinking, but no time now.
Oh for you modders, driver diameter opening is 26 mm. The driver uses a 26 mm contact board, bare, so looks easy to re-use for upgrading to a better driver. Easy to get out the driver from a retaining ring, extra wire length to pull the driver out of the pill, then a center screw is exposed which holds down the reflector (like many other multi-emitter lights - Shocker, etc.). Exposing the LED's reveals they are mounted on 16 mm stars epoxied down, nice centering plastic pieces, wired in series. Soooo perfect to mod!!
I'm definitely thinking XML U3's on 16 mm SinkPAD's, and the driver, maybe the 3.5A IOS custom - 2-3 cells, 1-3 LED's...
Nice results Tom E, I wish I have it at my copy.
I have one and it's very bright .. The similar lights I just got from wallbuys including the TR3 are not even close . I was happily impressed .I assume it was one of the best deals on wallbuys at 10$.. Nice light
Can these driver be modded for more current?
My light has only 1,6A on two cells. 
Pictures taken from CPF
Boaz, could you measure current at the tail?
Thanks a lot for the review! Frontpage’d and Sticky’d.
Finally got to modding my STL-V2. I had the driver for months laying around. I now get 3.9A measures at the tail, and 2,764 lumens OTF at 30 secs.
This is really nice now - like the feel better than a SRK, and this throws pretty well. The driver is no longer sold at IOS, but that's where I got it. Simply lo-med-hi, but well regulated. This light has a solid one piece design - no separate pill, lot of aluminum.
Mods: driver replacement (26mm rated for 2.6-3A per LED), 22 gauge wires, XM-L2 U2 1C's on 16mm SinkPADs, pill top and stars sanded to 2500 grit (mirror like finish), AS5 under the stars, DeoxIT Gold on contacts, coper braid driver spring, 50mm AR lens installed (stock lens is 51.7mm but it fits ok). The AR lens added 85 lumens.
I’m glad you’re happy with your STL-V2 Racer. I got one from FT and it was the worst light I have ever purchased. I think they had a return lying around, and cobbled it back together with whatever parts were laying on the shop floor. I’m still looking for a driver, but I hate adding another $20 to the $35 purchase price. It might be better to purchase a $55 light.
Shoddy STL-V2
Ouchy - ohh yes, forgot, I read your thread, posted on it. Dunno wut to say, accept it's all a crap shoot. My STL-V2 is a beauty - think I bought it at MF, long before I knew about FastTech, or if they existed then.