Review: NITECORE P20UV Tactical light with UV (1x18650, 2xCR123 or 2xRCR123)


Flashlight Enthusiast
May 5, 2010
Hove, UK
Author's Statement for Transparency and Disclosure
The test sample/s featured in this article were provided for technical testing and review by "NITECORE / SYSMAX Industry Co. Limited". Test samples are retained by the reviewer following publication of the completed review for the purposes of long term testing and product comparisons.

NITECORE have a very wide range of lights which increasingly offer a very large range of output options within each individual model. In releasing the new Precise range models the P10, P20 and this the P20UV, the number of modes has been pared down to the minimum for 'tactical' use.

The P20UV is actually the most complex of this range, but as you will see it is still incredibly simple to use and well suited to fast action scenarios where you don't want to be 'thinking' about mode selection.


Author's note: many of the images used in this review are animated to reduce excessive scrolling. You may need to wait for the images to load fully.

Taking a more detailed look:

The photos here show; the packaging, contents, accessories, holster, main and UV LEDs, reflector, tail-cap switches, tail-cap battery contact, tail threads, head contacts, 18650 cell next to the P20UV's CR123 battery magazine, size comparison, P20UV next to an 18650, the P20UV with D2 Digi Charger getting ready to go!.

For the size comparison, the P20UV is shown with (left to right) the NITECORE CU6, EA41, P20UV and P25.


The Beam

With a big clue in the name, the P20UV is not limited to white light. It has four auxiliary 365nm UV LEDs set into the reflector giving it the ability to check security features on documents and currency.

Despite this compromised reflector, the beam of the P20UV is very good with a defined hotspot and very usable spill. Outdoors the hotspot gives a good range and the spill is still useful.


Moving onto the UV output, it is not so relevant to attempt to show a normal beamshot, but instead here are some UK security marking being illuminated by the P20UV's UV output. The two photos show the scene with some background illumination, and the pure UV illumination where only the security features are lit. Included are UK bank notes £5 and £10, and part of a UK driving license photo-card. All are clearly lit by the P20UV making it very easy to confirm the validity of these items.


Modes and User Interface:

Being targeted towards the 'tactical' market, the P20UV has features specifically designed for this type of use.

The tailcap has two switches, a Forward clicky main switch, and a momentary only 'STROBE READY' click switch.

The P20UV can be pre-programmed into one of three modes which include differing number of output levels.

Tactical Mode – includes only High, UV and Strobe
Law Enforcement Mode – includes Medium, High, UV and Strobe
General Mode – includes all output levels, Low, Medium, High, UV and Strobe

To set the P20UV's mode, loosen the head, hold down the 'STROBE READY' button and while doing this, tighten the head. The P20UV then gives one, two or three flashes to indicate the active mode. Repeat this procedure to move through the modes.

(NOTE: The review sample exhibited an unexpected behaviour, in that if you used any of the P20UV's output levels immediately prior to changing modes, or in between several consecutive mode changes, the brightness of the indication flashes might either be bright or dim. Also, if using the P20UV immediately prior to a mode change there could be an additional bright pre-flash before the mode indicator flashes. This behaviour did NOT affect the function.)

With whichever mode is set, the main switch provides momentary or latching constant output levels (including UV), and the 'STROBE READY' button either changes output level if the P20UV is ON, or if it is OFF, this provides instant access to Strobe.

Whatever mode you are currently using, pressing and holding the 'STROBE READY' button for 0.5s will turn on the strobe. When you let go it will return to the previously used output level.

(NOTE: As the 'STROBE READY' is designed to give instant access to strobe, it is important to be aware that in the test sample, if the main beam has been used, but the P20UV is OFF, the first time the 'STROBE READY' button is pressed, it can take up to 1s for the strobe to come on. It is possible to 'prime' the strobe output by giving the 'STROBE READY' button a quick press, after which the strobe will come on instantly. Knowing that this is the case, you can ensure the P20UV is ready for instant strobe by priming it.)

The P20UV has a battery level indication. When inserting the battery, the main tail-cap switch will flash 1, 2 or 3 times to indicate charge level. Three flashes represent a full battery.


These are just the main features, for more detail see the full user manual here:
NITECORE P20UV User Manual

Batteries and output:

The P20UV will run on 18650, CR123, and even RCR123 making it more versatile than most single 18650 lights. NOTE: due to physical reverse polarity protection, the P20UV can NOT use flat top cells.

When using either CR123 or RCR123, the P20UV comes with a cassette to hold the two cells and prevent excessive cell rattling – this is a nice touch. You do not 'need' to use this, but it makes for a better fit for the cells.


Keeping this test Completely NITECORE the P20UV was powered using the NITECORE NL-188 3100mAh 18650 cell charged with the Digi Charger D4 and D2 chargers.

To measure actual output, I built an integrating sphere. See here for more detail. The sensor registers visible light only (so Infra-Red and Ultra-Violet will not be measured).

Please note, all quoted lumen figures are from a DIY integrating sphere, and according to ANSI standards. Although every effort is made to give as accurate a result as possible, they should be taken as an estimate only. The results can be used to compare outputs in this review and others I have published.

NITECORE P20UV using NL-188 3100mAh 18650I.S. measured ANSI output LumensPWM frequency or Strobe frequency (Hz)
High775330 (audible whine)
UVUnable to measure0

Measured beam range comes in at 155m. Strobe frequency measured at 17.5Hz.

It has been noted that I am particularly sensitive to PWM, and for me the PWM is unfortunately noticeable, but mainly on the Low output. On High I have not noticed it, but there is an audible whine which is much quieter on lower levels.

The following images are snapshots of the oscilloscope trace for High, Medium and Low white outputs, with the PWM showing clearly. Even on High, the PWM duty cycle is 50-50.


As there is an electronic switch in a dual switch tail-cap, there is a secondary tail-cap circuit which introduces parasitic drain. Once the power level flashes have completed the drain stabilises at 83uA meaning it would take 4.26 years to drain a 3100mAh cell.

With the maximum output level, the P20UV maintains this at peak output for nearly 2 minutes, and then the output is gradually ramped down to the Medium output level by three minutes from switch on. Turning the P20UV off even momentarily restores this to the maximum output level for a further two minutes with a ramp down to Medium as before.

The initial graph shows just this initial part of the output:


And then the full output trace for High with no output reset carried out.


Due to the initial high output, the ANSI runtime terminates with 80 lumens still being output at 4h 48m.

The P20UV in daily use

Not being either a LEO or in the military, my own impression of the P20UV is based on a hunting and civilian perspective.

For an 18650 light, the P20UV is nice and compact. Yes there are more compact single 18650 lights, but the P20UV packs in the additional UV LEDs and a larger reflector for better beam shaping, which would not be possible with a smaller head. It feels a good size in the hand and is in the 'reasonably EDC-able' size range for most people.

The dual button interface is easy to use, but it is also easy to press both buttons at once, especially when wearing gloves. This is not exclusive to the P20UV, as most other lights with a twin switch tail-cap have the same issue. When wearing gloves you simply can't feel the switches. I have ended up blasting the strobe by mistake from time to time.

Having instant access to strobe, gives direct access to a potentially disorientating blast of light allowing you to take other action (run away?) if confronted or attacked. Most other lights with strobe do not have such instant access. If you have primed the strobe (see Modes and User Interface section for a note on this) you have instant access to this feature.

The UV output is excellent, and once you get used to having a good 365nm UV light, you will find it is not just retailers checking bank notes, but you will as well. It also provides a good source of entertainment to look at different things under 'black-light', but be warned, if you ever use this to look around your kitchen and the cooker, you might never want to prepare food there again. However well you clean, the UV seems to show rather too much for my liking!

With its pre-set 'modes' the P20UV makes customising the output levels exceptionally easy. Even with the UV output, the P20UV can be a simple three level light with High, UV and strobe. If you don't touch the 'STROBE READY' button, then the P20UV can become a single output light. This degree of simplicity is excellent for stressful situations, or for lending the light to someone else. At any time you can change the 'mode' in a matter of seconds and give yourself more output levels.

I really like this simple way of setting up which output levels are available, and would have liked even more 'modes' to be included (perhaps a mode that has a LOWER level and a one that removes the UV output).

The P20UV does have a couple of minor design quirks that have been described earlier in the review, but they are of no real concern. Having noticed them during testing, I have reported them here for your information (as you might find them too).

Having a soft spot for UV lights, the P20UV appeals to me more than the P20, but this is a personal view. The P20 will have a slightly cleaner beam pattern and a simpler Tactical mode due to not having the UV output.

This P20UV generally stays in UV mode (I said I had a soft spot for UV), and is my preferred choice of light to take with me on those occasions where I feel the need for quick access to strobe. In addition to these specialist outputs, the constant white output levels are well spaced, making this a great all-rounder as well.


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Flashlight Enthusiast
Jan 25, 2014
Blue Ridge Mountains, VA
I've got a question for you. The animated gif shows 4 cut-outs in the reflector for the UV LED's. Does the light have three UV LED's or four?

If it has four, your review indicates three.


Flashlight Enthusiast
May 5, 2010
Hove, UK
Thanks, and well spotted. It does indeed have four UV LEDs.

The review is now corrected.
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