The XTAR S1 is a beast of a light and the flagship in XTAR's current lineup. They tout it as a "Rescue flashlight" with 2,350 lumens and 475m of throw to go along with it.
These are outstanding numbers to be certain and should serve those fulfilling SAR duties well. I am fortunate in that my most extensive SAR duty to date has involved looking for the TV remote trapped between the sofa but suffice to say that should I need to call upon it for more serious matters, I'm confident the S1 will serve me well.
I have received a finalized production version for review but given there are already excellent ones comparing this production version against the pre-prod one (done by candlelamp and selfbuilt), I will not be covering any of that here.
MFG SPECS
MSRP: $299.99 USD
Max Duration: 2350Lm/1hrs20Min (Tested by 3 x 18650 3100mAh battery)
Constant current circuit - maintains constant brightness
Smooth reflector, throws beam over 475 meters
Powered by 3x18650/3x18700 button-top battery.
Ø 83mm(Head dia)x Ø 47mm(Body dia)x 240mm(length)
888-gram weight (excluding batteries)
Made of durable aircraft-grade aluminum
Premium Type III hard-anodized anti-abrasive finish
Waterproof to IPX 8
Magnetic ring switch
Anti-roll, slip-resistant body design
Accessories included: Flashlight, Lanyard, Pouch, Spare O-rings, Manual, Warranty card
PACKAGING & CONTENTS
The XTAR S1 arrived in a nice thick cardboard box surrounded by ample foam cushioning:
Given I'm often asked whether 18700-sized batteries will fit in XXXXX light in my reviews, I decided to purchase six of their 2600 mAh batteries along w/the WP6II charger (these are included as part of the kit and the batteries are shown packaged with the S1 in last pic above):
DESIGN & FEATURES
As befitting its main purpose the XTAR S1, is a large light weighing in at 888* grams without batteries with a 3.26” (82.9mm) bezel with a nice AR coated glass:
(*which incidentally is a most auspicious number for Chinese people so I wouldn't be the least bit surprised if this was intentional 
)
The glass is surrounded by eight crenlations that allows one to see if the light is on if stood on it's head:
The two patterned rings provide some grip but not too much:
There are five cooling fins that aid heat dissipation, however it actually doesn't run all that hot (see runtime section for temp graphs):
These five fins alternate between eight flat and eight curved columns:
Just aft of these fins is a ring with the output and mode selection:
...and then the control ring itself which has the selection indicator engraved and is completely smooth save for these scallops machine in ladybug print:
They have been sanded so that while not sharp provides just enough traction to allow easy use.
The 3 x XM-l's are fitted into a deep, smooth, combo reflector that give it tremendous throwing capability:
Each LED is centered perfectly through the use of centering molds.
The head, body and tube can all be disassembled from each other:
The tube features machined grooves that run perpendicular to each other:
...that are pretty functional as well (see Size & Handling section for further details).
There are two "flat sides" on the tube with one featuring the company name and logo and the other bears the model and serial number:
The texture provides a good grip and offers a nice contrast to the smooth grooves:
SIZE & HANDLING
L to R: XTAR 18700 | NITECORE TM11 | Niteye EYE30 | Elektro Lumens Big Bruiser | Sunwayman V60C | Niteye EYE25 | XTAR S1 (Production)
At the risk of repeating the obvious, this light is BIG! It's easily the largest one in my collection, however, as compared to some other lights (e.g. SR90, TK70), it's actually downright petite considering the output/throw it's capable of.
Given the three cell configuration, the size of the tube comes in smaller than say the four-cell TM11's:
XTAR S1 tube (L) @ 1.83" (46.5mm) vs. NITECORE TM11 tube (R) @ 1.96" (49.9mm)
MEASURED PERFORMANCE
As part of a new standard for my reviews, I measure the performance on my PVC LMD by first calibrating the sensor's positon w/a Xeno G10v2 (immediately perfectly regulated in med. mode). All readings taken @31 seconds (to conform w/ANSI FL) and ambient temp of 75F (24C).
Left: Given I needed to hit the 4K range on the Extech HD450, I calibrated the sensor with the G10v2 on high for 480lm
Middle: S1 ready for lumens measurement and runtime testing
Right: lux reading
And here are the measurements: High: 2560lms (60.5K lux @ 1m)
Here is a video explaining a little of the process and my new method for conducting runtime testing based on measured lumens rather than relative output. The goal of this is to provide an idea of real world lumens as an average for non-regulated lights.
[video=youtube;VR1Aeqe1A24]http://www.youtube.com/watch?v=VR1Aeqe1A24[/video]
Sorry I'm still new at these so it's not particularly good but it'll get better. 
BEAMSHOTS
Beam angle
[to come]
Indoors (5m)
Max
Min
For details of the above indoor shots and comparo vs. many other lights, please check Epic Indoor Shots Trilogy
Whitewall Hunting
Exposure settings sequentially from top left: 1/25, 1/100, 1/800, 1/1600 @ f2.9 on AWB (light is ~.4m to wall / camera ~.59m):
RUNTIME & BATTERY CONSIDERATIONS
The relevant battery stats are provided above each runtime graph along with:
- Voltage of the battery at the start and end of the test
- Current draw as taken right before the test
- Actual runtime using ANSI FL1 (first in HR and then in M so for the XTAR 2600's read this as 1.2hrs OR 71min)
- For High, captured the temperature: ambient, the head at start and the max it reached (fan was used for all bats)
Before we dig into the run time, using XTAR 18700 2600 mAh cells I measured the following current draw:
1 cell - 4650mA
2 cells - 5200mA (2600mA each)
3 cells - 5820mA (1940mA each)
Keep in mind that that the cells are arranged in parallel so the load will be reduced beyond one cell with three ultimately only drawing roughly 2A each.
With that said, I was able to achieve 1hr and 11min with the XTAR 2600mAh batteries (note the decently regulated run). I fully expect to meet (actually beat) the claimed 1hr 20min runtime w/RL 3100's (which I will test later).
Also, with a light capable of this output, heat is always a potential concern but as can be seen from the graph above, the S1 doesn't get all that hot on three cells. Here is a clip covering the temp check abut 10 minuites into the runtime as well as additional details about the PVC LMD:
[video=youtube;4JgjCTW061k]http://www.youtube.com/watch?v=4JgjCTW061k[/video]
However, if dealing with 3 batteries are a hassle, given there is ample room in the core of the tube, one can use non-flat top 26xxx/32xxx batteries (provided they are able to withstand 5A sustained). Careful alignment of the negative side of the battery w/the prongs in the tailcap are required to ensure proper contact, otherwise there may be risk of overheating due to poor contact points:
(26650 battery shown above)
[NEW 4/23: I've now conducted runtime testing on KK 26650 and RL 3100's. So the trade off for simplicity in dealing with just one battery is seemingly just 10 minutes of total runtime but as the chart shows, also a whole lot of output.
As for the RL3100's these nickel-containing cells have a lot of staying power allowing it to reach 2.4hrs before output dropped below 10%. Albeit the latter half of the run is not regulated but again, now that these runtime charts are conducted in real measured PVC LMD lumens you can have a real understanding of just how much lumens is lost during non-regulated runs.
I'll be testing some IMR's next and will also add 32xxx cells when I pick up some in the future.]
[EDIT 4/24: Given the S1 is well regulated, it doesn't receive any added benefit by running IMR's. As a matter of fact, the low capacity of these cells really hurt the runtime in this 1S3P setup. The light only draws less than 2A for each cell. With that said, it should get interesting though on 1-2 cells runtime testing which I'll do in the future.
As a side note, the temp on the KK testing is off since the thermocouple was in direct line of the fan thus causing the erractic line. In reality, it should be closer to the other runs but again, overall the S1 doesn't really get unreasonably hot.]
PHOTO GALLERY
MORE TO COME...
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S1 provided by XTAR for review
Hey sorry, there were two videos that didn't come through in the copy/paste so if you didn't see them, hit refresh in your browser.
It covers how I'm doing realtime lumens measuring as part of my runtime testing so in the future, for non-regulated lights I'll be able to give a real world average as to what can expect for the output.
I want!!
Looks like a man's light. Gotta have deep pockets for this one.....
That XTAR S1 is quite the beast.
Excellent review, turboBB.
The combination of throw and brightness is just impressive! The only thing stopping me from getting one now is the price 
Agreed, I want one, my bank account doesn’t, haha.
The beamshots sting my eyes!
Excellent light and excellent review. The S1 has been a dream flashlight for me since the first time I saw it.
jealousFoy
Thanks for the review and the extra bits, they make this light more desirable.Nice to know it can run on a 26650 that is capable of delivering the amps too.I'd love to get one but blew the budget this month
,maybe next month.
Thx guys! Runtime testing with 1 x KK 26650 and 3 x RL3100's added.
Thank you for a great review. I'm really impressed with the output and run time of this light, and the build seems fantastic. A very big light though!?? A real keeper. Pitty about the price. While it may be worth it, it pushes itself out of most of our budgets, especially as there are so many good triples out there now. This appears to be one of the best throwers though?
what's the different between this unit and pre-production?
only cosmetic changes???
Video said 10% brighter!
Design and Features section now added but I still have more to add to that as well as the rest of the review.
Cheers,
Tim
Whitewall shots now added.
Where can i get the production version of this light?