[Review] NITECORE SRT3 Defender (XM-L2 T6 CW, 1x (R)CR123, AA, 14500)

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UPz's picture
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[Review] NITECORE SRT3 Defender (XM-L2 T6 CW, 1x (R)CR123, AA, 14500)

LED: CREE XM- L2 T6 CW, 5mm LED for blue / red light.
Battery: 1x CR123, 1x RCR123, 1x AA, 1× 14500 (with extender adapter included)
Modes: Variable magnetic control plus fixed positions.
Switch: Forward in the tail, magnetic ring.
Date: July 2014
Nitecore / Flashaholics.co.uk / ForoLinternas / RdL

The smallest flashlight that conform the Nitecore Smart Tactical Ring family is this little SRT3, a relatively compact flashlight that promises high performance and an user interface very similar to their bigger sisters, such as SRT7 with a third generation magnetic ring that combines, by an ingenious system of detents, the freedom of the fixed and variable output adjustment and special modes and auxiliary colored light within a single integrated optics.

The presentation is similar to what we have seen previously in other relatively new in the same brand flashlights: A printed cardboard box contains inside a small plastic tray in which we find the flashlight (which comes with the adapter / extender for AA/14500 installed), a standard nylon fabric holster with velcro closure and different types of fastening, classic paracord adjustable wristband and a small plastic bag containing a set of spare o-rings and switch cover. As usual, user manual (in English) and warranty card is included.

The SRT3 has a compact finish, but its dimensions are significantly greater than those of other alternatives such as Sunwayman V11R, thanks to having a reflector somewhat larger both in diameter and depth.

Anodizing differs from classic black, and has a grayish tone pulling to copper, similar to the popular military gray Nitecore P25 Smilodon. We found several engravings on anodized aluminum, like logo and model planes located at the battery tube and a serial number on the head, all of them very sharp and easy to read.
The flashlight shape recalls other companions in the range, such as SRT7 with localized similarities especially in the head of the flashlight.

The flashlight features a bezel steel with sandblasted finish with three discrete and nothing sharp defensive battlements. The glass lens has as usual AR coat treatment, and the reflector is smooth immaculate with XM-L2 correctly focused on his bottom, and a small bicolor LED installed on a perimetral reflector hole.

The magnetic ring is machined with good knurling offering more than acceptable grip, resulting simple one-handed operation, and making it easy to detect the various detents that are distributed throughout it’s nearly 360 degrees of rotation.
Under the ring we found a hex head area, which acts as an anti-roll mechanism, preventing the flashlight roll upon itself effectively.

Inside the head there is a protective mechanism against the installation of batteries with reversed polarity, similar to the concept seen in other Nitecore models, with no positive contact spring.

The threads are anodized and come with a trapezoidal -cut, slightly greased from factory running very smooth and free.
The adapter-extender for AA/14500 obviously has the same type of threads, and allows us to install AA batteries, avoiding the rattle thanks to its smaller internal diameter. This part has its own o-ring, so the sealing assembly is not compromised when using the extender.

Inside the tube at the bottom we saw the negative contact, carried by a spring on the printed circuit forward switch. This switch is identical in touch, stroke and hardness of many other Nitecore flashlights, such as P12, P25, SRT7, MT1A …

The tailcap switch assembly is hold in place by a threaded piece with finish similar to sandblasted bezel, and has a silicone coating for the button seen in previous models that use the same tactical switch.
The base of the tailcap allows for positioning the torch in tailstand safely, since the button is recessed and completely surrounded by a circular surface that has several bores for the installation of the wrist strap, in addition to the two threaded holes in which the pocket clip is held.

This clip is thankfully different models common in other Nitecore, not being held by pressure as in MT1A, now bolted to the flashlight, as in the EX11 for example. Clip design seems elegant and well resolved, with a similar finish seen in other Nitecore clips, thermally treated titanium plated finish, with good tension without actually seem flimsy or too hard.

The user interface of this Nitecore SRT3 is very similar to what we saw recently in SRT7 with a magnetic ring for mode selection and variable adjustment of intensity, combined with a forward switch on the tail of flashlight that allows us momentary activation at any ring position.

The ring has approximately 360 ° degrees of rotation, with a fixed beginning and end. Within this dial, we found several detents, points where the ring is fixed by the pressure of some internal mechanism, and wherein we notice a click to enter and need to exercise a little more force to jump to the next. Among these, we found a zone free of detents, designed for variable adjustment.

  • On and Off: The SRT3 is activated by a forward mechanical switch in tailcap. The light activates in the position corresponding to the ring mode.
  • Variable adjustment: The detent-free zone is adapted to adjust the light output from a range of 550 and 0.1LM (with a RCR). Upon reaching the minimum and maximum we find a detent, very useful if we want to use the flashlight like a “single-mode”, with always the maximum power available and controlled by the tactical switch. This SRT3, unlike the SRT7 lacks a standby position.
  • Strobe Mode: From the detent of maximum power, there is an ultimate position further to the right, where the strobe mode is. Again, the combination of ring and forward switch and gives us the ability to have it ready to turn on the flashlight in strobe (defensive or offensive use) directly from the tailcap switch.
  • Auxiliary color light: Returning to the point of minimum output, and instead of turning the ring clockwise, counterclockwise now. The first detent we found belongs to the red light, and the next to blue light. This multicolor light produced by the small built-in in the reflector LED offers not comparable performance to the XM-L2 performance. The SRT3 dispenses with the green light present in other higher models of the SRT range.
  • Police Strobe: The following detent counterclockwise from the blue light leads us to a police strobe mode, where quick bursts of red and blue light alternate quickly.
    SOS Mode: Following the dial in the same direction we found the SOS mode, which uses the XM-L2 to show the Morse code sequence.
  • Beacon Mode: The last ring detent counterclockwise is reserved for beacon mode, wherein the flashlight emits a brief but powerful flash of white light every two seconds, useful as a localization signal.

Overall, as in the SRT7 this SRT3 has a complete user interface thanks to the combination of forward switch and magnetic ring which is easy and intuitive, and can be mastered in just a few seconds, even with the absence of ring positioning engravings or labels.
Instead of the typical bar chart in which we usually compare the specified and measured performance, I again bet on an analysis of the area variable degrees of tilt adjustment ring. We are going to measure, in increments of 15 degrees, the output measurement obtained along the area of variable adjustment, translating to a graph to see how increasing output behaves. I’ll also add some similar flashlights that are controlled by variable magnetic ring so that we can compare how the pattern is.
To avoid confusion, I have chosen to convert measurements to percentage of each on the maximum reading obtained in each sample.

The first thing that strikes us is how different total inclination angles of SRT3 which is provided against the “competitors”. Furthermore, we see the V11R, RRT01 and EYE10, each having about 120 degrees, focus most of the action in the last 60 degrees. The SRT3 has a much more gradual curve, and we can see the line drawn has a very different pattern from the other three.

In this second comparison chart I have reflected an interpretation of the visual perception of the increases at each step, applying a correction factor according to the teachings of the Steven’s power law. Remember that the visual perception of the human eye to increases in brightness is not linear. These lines correspond to how our subjectively vision reacts to increasing output against completely objective data captured by the integrating sphere sensor.
Again, the SRT3 takes advantage of the larger variable area, but also we see, after the correction factor, the increase is much more linear and natural to that found in the other three flashlights, which have a big jump between 60 ° and 105 ° of its rings being the adjustment within that range pretty vague compared to what we get with the SRT3.

Thanks to the SRT3 wide range of possibilities of feeding, we can choose between 4 types of batteries: Primary and rechargeable CR123a / 16340 format, primary and rechargeable AA and rechargeable li-ion 14500.
For the preparation of the graphs of runtime vs output, I opted to use two types of rechargeable 16340 (also known as RCR), which are the Nitecore NL166 and powerful AW IMR 16340 in addition to the usual Sanyo Eneloop AA “2000mAh”.

Again, Nitecore has chosen to implement a time-controlled stepdown for maximum ring position, reducing output within three minutes of activation. Thanks to this stepdown the SRT3 has increased runtime, greatly improving efficiency with a second much more linear phase due to subdued demand.
In the graph you can see that both the AW IMR as the Eneloop, the line has a singular curve in its closing stages, once loses regulation that could well be interpreted as a warning of low voltage. With NL166, being the small battery built with protection circuit, the flashlight goes black with no signals at all. Also, as a curiosity, we see the curve obtained with the Eneloop has a clear three minutes output stepdown, although in this case the downturn is invaluable to the eye.

In the chart below we compare the SRT3 to the most popular similar light ruled by a variable adjustment ring as user interface, the legendary Sunwayman V11R, in this case the first generation version with XM-L U2 again with the three previous battery options. As I mentioned, thanks to the stepdown the Nitecore SRT3 can grab a significant handful of extra minutes, with a much higher linearity.

Looking for detail the early stages of each line, we will limit the time to 5 minutes in this enlarged graph. The SRT3, thanks to XM-L2 obtained higher peak values in all analyzed options, with almost 700LM instant activation with the powerful AW IMR.

Finally, we compare the SRT3curve against known Niteye EYE10, JETBeam RRT01 and again the Sunwayman V11R U2, this time only with the mundane Nitecore NL166battery. Again, thanks to the gained stepdown efficiency enables the new Nitecore regulation for extra hold more than 15 minutes in front of the other three popular flashlights.

With its smooth and substantially greater than those of alternative dimensions reflector, SRT3 offers a fairly different from the typical flooder reflectors, with a well-defined hotspot beam. As in SRT7, the hole in the reflector to accommodate the small bicolor LED shows no traces of shadows or artifacts in the wallshot.

The tint is typical XM-L2CW, ie. slight greenish yellowish halo in the transition between the hotspot and spill.

Nitecore specifies a maximum throw range of 134, 105 and 79 meters for RCR, CR123a and AA respectively, slightly above average in this format.
The beam profile of the auxiliary light, as expected in this type of combination of multicolor LED built into the side of the reflector is very similar to what we saw in the SRT7, with the typical combination of artifacts and dark areas, amplified by the reflection for the XM-L2 reflector.

Undoubtedly, the SRT3 is a complete flashlight with a great user interface that offers incredible versatility combining the best of the variable adjustment and special fixed modes, all controlled by a traditional forward switch in the tail.

M11R • D25C • EX10 • EYE10 • RRT01 • V11R • SRT3 • F10R

Negatives: Undoubtedly, the weak point of this flashlight is its size, as it far exceeds the usual volume of similar alternatives, but as counterpoint is more comfortable to grip and operate than the extremely compact options, as EYE10 or RRT01.

Logically, with the extender adapter for AA / 14500 the issue repeats, and continues well above the average size, especially compared with only-for-AA flashlights. Also, I think the beam of the auxiliary color light has a large room for improvement, being this time much less powerful than in the SRT7, by using a single bicolor LED.

Positives: The strength of this small SRT is undoubtedly its very comprehensive user interface, which in a relatively compact size offers very precise variable adjustment, special and auxiliary modes of color light and the momentary on by mechanical forward switch. The exterior finish is excellent, and with a very personal and distinctive air of the SRT series. Its performance and regulation seem well above average, especially compared to the typical lights, designed for primary CR123a, but which supports rechargeable Li-Ion in “direct-drive” mode. If the small size is not your priority, this SRT3 is a flashlight you should not miss.

Edited by: sb56637 on 09/02/2017 - 12:01
JohnnyMac's picture
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Nice review! Thanks for the effort. Smile

harry218's picture
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Thanks for the nice review! That is one big a$$ 123 light. Big Smile

InfinitusEquitas's picture
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Also the bodies between the SRT3 and SRT5 are completely interchangeable.  They are identical except the SRT5 head is driven harder.

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One thing I didn’t like about the SRT3 is that you have to push the button down too far to engage momentary. Often I’d push too far and end up clicking the power on.

UPz's picture
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bgyen wrote:
One thing I didn’t like about the SRT3 is that you have to push the button down too far to engage momentary. Often I’d push too far and end up clicking the power on.

I have so many nitecores equiping this same switch that I am used to it. Actually, I never noticed till your comment, and yes, the activation point is somehow deeper than other brand switches.

Thanks for the replies!

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Thanks for the nice review UPz!

Deputydave's picture
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InfinitusEquitas wrote:

Also the bodies between the SRT3 and SRT5 are completely interchangeable.  They are identical except the SRT5 head is driven harder.

I was doing a search on the SRT5 and saw this post. If I’m understanding this correctly, the SRT3 and SRT5 heads are the same and the tubes can be interchanged? I have an SRT3, if they can be swapped, can you buy the 18650 tube to use? Or does any other type of 18650 tube fit the SRT3/5 head?

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