[Review] NITECORE P20UV (XM-L2 T6 /4x UV LEDs, 1x 18650/ 2x (R)CR123a)

LED: CREE XM-L2 T6, 4x 5mm 365nm UV LEDs
Battery: 1x 18650, 2x ®CR123A
Modes: 5 (Low, Medium, High, UV Light, Strobe)
Switch: Double switch on the tailcap
Date: December 2014

Recently Nitecore has thickened considerably its Precise line, which includes brand proposals for Tactical / Police / Security tools.
The Nitecore P20 was launched first as a compact tactical flashlight with XM-L2 and smooth reflector. Now the famous Asian manufacturer has introduced an interesting variable, which is the flashlight we are reviewing today. This is the Nitecore P20UV, which as its name tells has an ultraviolet light of 365 nm wavelength through the installation of four small 5mm LEDs integrated into the reflector, in this case with orange peel finish.

The flashlight comes as usual in the typical printed cardboard box of the brand, which inside has a plastic tray and along the flashlight contains a fabric holster with velcro opening and a handful of accessories like are pocket clip, the classic paracord lanyard, a tactical plastic ring grip, a set of spare o-rings and silicone coating for main switch, and as a new cartridge adapter for using two CR123A, RCR’s or 16340 as it was a single battery, thus avoiding the typical rattle these batteries, two millimeters narrower in diameter against the almighty 18650, usually happen when installed in flashlights that can run on both input voltages.

Of course, we also find the user manual and SYSMAX classic warranty card.

Except for the changes in the flashlight optics to provide ultraviolet light, the rest of the P20UV is exactly the same as the P20.
This is a simple and relatively compact tactical flashlight with a head diameter of about 32mm, and a total length of 135mm.

Made of black color anodized aluminum, the body of the P20UV has several laser engravings all perfectly defined and very easy to read with high contrast between white lettering and black background.

The head of the flashlight features a bezel, also in anodized aluminum, topped with three discrete crenellations. The neck is topped with a machining that prevents the flashlight from rolling when placed on a flat surface.

The optic of this P20UV is quite unique. In the center we have an XM-L2 perfectly centered by a black centering disc. Four equidistant holes house the small UV LEDs. The reflector now becomes textured, presumably to avoid aberrations produced by the holes for the UV LEDs on the beam for the white XM-L2 emitter. As always, optics is finished with glass lens featuring AR treatment, common in all the flashlights of this brand. Inside of the head we can see the circuit, which dispenses the spring for positive contact seen in other flashlights in this range, but still incorporates a classical mechanical protection against the installation of batteries with reversed polarity so that the flat top batteries will not function correctly.

Head threads are trapezoidal head cut, and are anodized. The tailcap threads have triangular cut tailcap and match the ones also found in the P12, P25, MT2C, MH2C … so the remote switch accessory to use the flashlight installed on a firearm, is compatible also with this P20UV.

The tube has two opposite planes in the central area, where the brand has a laser engraved logo, model and patents. The central part is finished with a non-aggressive knurling. At both ends of this knurling there are two tracks for attaching the included clip, so we can install up or down as we like or need.

Among the tailcap and tube have an area that is intended for installation of tactical ring, but unfortunately this design is the same as we have seen in many other Nitecore, simply trapped between the two parts and made of plastic.

Finally, in the tailcap we can find much of the charm of this flashlight, and its user interface will discuss in detail later. This tailcap has as novelty a system Nitecore has now, although already seen in some Klarus tactical models, where we have two separate buttons on the same plane tailcap: We have a forward switch, with the design of the coating common with previous Nitecore flashlights, slightly off from the center of the flashlight. This switch profile protrudes, easily identifiable to the touch and quick access. Along with this, we found a flat lever with the inscription “MODE” for changing modes and “Strobe Ready” function. This lever acts on a small button hidden under it. Unlike as P12 with or similar to previous Nitecores, the P20UV switch is not removable and the circuit appears to be directly embedded rather than threaded. Of course, this flashlight can’t tailstand.

There are many people I know who, professionally dedicated to guard tasks or different police uses, say me say that many of the lights I analyze are too complex in its user interface to be considered real tactical options, because in situations of risk or panic we are often unable to recall correctly as access this or that mode.

However, in this P20UV, as in the P20, has incorporated a fairly complete user interface with three main modes for white light, a fixed intensity to the ultraviolet light, and a fast access strobe mode. Not happy with this, the user interface can customized with three selectable modes groups.

  • On and off: The P20UV is turned on and off using the classic forward switch button located at the tailcap.
    Momentary On: This button can turn the flashlight momentarily, short bursts or making signals / morse code without pushing the button until the click.
  • Changing Modes: The modes are changed by the appended lever. With the flashlight on, press the lever “MODE” to toggle between modes in ascending order.
  • “STROBE READY”: This is an interesting defensive/offensive feature that allows instant access to strobe mode with flashlight on or off. With the flashlight off just hold the “MODE” button pressed and immediately an annoying and powerful strobe of variable frequency will start as long as we maintain the lever down. With the flashlight on, strobe access the same way, except that we no longer need to hold the lever down once we enter that mode. To return to the previous mode, simply press again.
  • Mechanical block-out: The P20UV can be locked mechanically by partial unscrewing of any of its threads. Being anodized, we interrupt the circuit and avoid accidental or involuntary activations.
  • Reading the state of charge battery /batteries: Using two small red LEDs integrated into the lining of the tailcap, the P20UV shows the state of charge of the battery every time we insert and screw completely the tailcap: Emits three flashes when the battery is above its 50% capacity, twice when it is below 50% and once when the battery is nearly exhausted. This indicator functions as a low voltage warning when we have the flashlight on, flashing quickly when you need to replace the battery.

This P20UV offers three groups of modes for different situations and purposes. We can select the group by a simple operation consisting in unscrew the flashlight head, and holding the “MODE” button and tighten again the head. The flashlight will issue a combination of flashes indicating the group selected modes: One flash for “Tactical”, two for “Law Enforcement” and three for “General”:

  • “General”: This is the mode in which the torch arrives for first use. This group has the three modes of white light, plus ultraviolet light mode and is designed for daily or general use. This group has memory and flashlight starts always on the last used mode, including UV light.
  • “Law enforcement”: Designed for a police patrol or use, this group has the medium and high modes in addition to UV light to check documentation. No memory and always starts in the brighter mode.
  • “Tactical”: Ideal for simple and direct use of the flashlight. Only two modes, High and UV light with no memory so the flashlight starts always on High, either by complete or momentary activation.

Therefore, in my opinion Nitecore has managed to meet some basic needs of professional users of military or police sector by incorporating two groups of very consistent modes in which the absence of memory make it become almost a mono-mode flashlight if we only act on the classic switch as always starts in the higher mode, regardless of the type of activation (full or momentary) very easily, without forgetting those who seek a more complete or everyday civil use. In addition, UV light mode can be used as well as ultra low mode, thanks to the wavelength of its emitting ultraviolet hardly generating visible light, being this light white and not violet as with other extended ultraviolet light frequencies.

(All measurements are taken following ANSI NEMA FL1 procedure, taking value of the highest reading between 30 and 120 seconds after activation. More details here)

The modes are well spaced in my opinion, with the available repertoire being very similar to the base version P20. High mode have declared 800LM, 400LM for the Med mode and one Low mode with 70LM (80LM for 2x CR123A) plus ultraviolet light of 365nm at 320mW, which hardly generates visible light and can perfectly be used as ultralow mode. Although I have to remind that the photodiode can only measure visible light, and cannot guarantee that the perception of this type of light corresponds to the human eye, I get a measurement of ~ 0.2LM. As usual, the values specified by the brand are quite reliable with those obtained in the usual test on the integrated sphere.

An interesting aspect worth mentioning is the type of regulation with which Nitecore has endowed this P20UV. The lantern has a “hybrid” regulation, which have two completely different phases for High and Med modes. After about two minutes, the flashlight starts a progressive stepdown that for a full minute, is gradually reducing its output to reach approximately 350LM, at which kicks in the second phase, in which instead of a flat regulation, the performance is at the expense of battery voltage.

In this way it becomes possible to obtain an “all in one”, with a high top for the first three minutes relatively high (though without forcing, moving comfortably into the three numbers without wasting energy for getting close promptly to four digits) later nothing less than light exactly 9 hours with the same 18650 battery of 3100mAh.
To appreciate better how the first few minutes of operation are, I have made this zoom in, to avoid the lengthy runtime excessively compressing the chart lines:

It is very interesting pattern to the progressive decline in the stepdown, and thanks to the gentle descent is almost imperceptible to the human eye. This new zoom in showing detail of how that complicated curve is drawn:

You can see how for about 60 seconds the flashlight suffers curious ups and downs.

Finally, comes the turn of comparing this P20UV performance at its maximum mode with other similar flashlights:

We see that the P20UV shows, thanks to the type of hybrid regulation shows a compromise between power and runtime, more inclined to the second virtue. Again, as in the previous examples, the huge runtime of 9 hours on a single battery prevents us from seeing clearly the details, so let’s focus on the comparison but this time limiting the time to 90 minutes:

The Nitecore P20UV is a flashlight that offers a mixed profile, with its compact head size and rugged reflector offers a floody profile, while retaining a decent range, which makes it a versatile tool.

The hotspot is medium in size, and gently rubs the gradient of the spill without some artifacts, probably caused by the presence of small integrated UV LEDs. The tint of the XM-L2 T6 is pretty good, with the typical yellowish trend in the gradient surrounding the hotspot.

On the side of the UV light, and making it clear from the beginning that my experience with this type of ultraviolet light is scarce, I will say that I was pleasantly surprised when comparing the tone of the UV light of 365 nm versus cheap ~400nm alternatives.

The P20UV emits very little visible light, and the predominant tint in this is white unlike other economic UV flashlights in which the highly visible violet light predominates. Contrary to what happens with the Nitecore Chameleon CU6 with 3W UV powerLED and own full reflector in the P20UV UV light is for short distances.

Here is an animated comparison of the UV light on two distinct areas: a fluorescent (a large sheet of white printing paper) and a non-fluorescent (a wall of my house). You can see how there is a difference between the light generated, especially in the P20UV that on the white paper creates a beam of violet / blue light while shinning on the wall only produces little light, and almost all white .
The economic flashlight with 395-410nm light generates much more visible in both scenarios; absolutely dominate the purple tint on the non-fluorescent wall.

Difference in visible light, Nitecore P20UV • Uniquefire 602C-UV

The beam profile of the four UV LEDs is also surprisingly good, without the typical artifacts that one expects from this type of assemblies with integrated LEDs into reflective surfaces such as in the SRT range.

In this animation we observe that the wavelength of the UV LEDs generate P20UV lot less visible light, so the fluorescence effect is much more visible. On the 50€ note see how the fibers are illuminated in all tones hardly distorting the print color scheme of the note, which the budget 3W light fails.

Beyond a tactical or forensic use, I found P20UV a fun and fresh flashlight, with some very interesting features as its interesting hybrid regulation, its excellent user interface with different configurations to meet real multitasking, compact size lightweight and smart STROBE READY function which surely will please the military-police-guard sector.

Fenix TK12 • Nitecore P20UV • Nitecore P12 • Olight M22 • Fenix TK22 GE • Nitecore SRT7 • Nitecore P25

  • Negatives: Although it may be a very subjective point, I think the stepdown for the Med mode is not justified with “only” 400LM. I can hardly find a logical reason for this behavior beyond the probable impossibility of having two types of regulation in the same kind of circuit.
  • Positives: As I mentioned, I was pleasantly surprised P20UV since the out of the box, first by its small size and weight, build quality true to the Nitecore standards or an intelligent user interface in which each user decides what their ideal modes sequence depending on the task to which allocated the flashlight.
    The UV light, beyond my hobbyist attraction or curiosity, has many virtues and thanks to the implementation type of emitters within the optics of the flashlight we will not be disturbed in everyday use of the XM-L2 white flashlight part. An excellent multipurpose flashlight.

Nitecore P20UV provided by Nitecore.co.uk for review. Thanks!

Awesome review, thanks for it!

I've always been interested in ultra violet lights, Tank007, ebay, a.o.

The Nitecore is a bit out of my price range, i spent so much already on group buys :D

Thank you for reading pipifax!

Thank you for the very detailed and technical review UPz :slight_smile:

You are very welcome!

Thanks for the great review!

sorry UPz that I missed this nice review, and not just me, you deserve more response for the thorough work you put into it.

Thank you very much djozz :beer:

Thanks for the lengthy reviews and beautiful pics!