NITECORE P25 Review (1x18650 or 2xCR123/RCR123)


Flashlight Enthusiast
May 5, 2010
Hove, UK
Riding on a wave of new innovation, NITECORE have launched the Precision Series, the P25 being the first of these. Combining the NITECORE’s two-stage switch with functional body design, a built-in Micro-USB charger, battery voltage readout, and a regular forward clicky tail-switch, the result is feature packed.


Initial Impressions:

The colour of the anodizing, incorporated Picatinny rails/heat-sink fins and two-stage switch with blue illumination, all give the P25 a futuristic look.

Amongst my work colleagues it has elicited a great deal of interest in, what has been described as, ‘a light sabre’ and ‘something out of Star Trek’.

Fit and finish is amongst the best I’ve seen with rich anodising in a grey/green/brown shade. It handles so well, with the side switch making it comfortable to operate and giving you access to all the main features.

What is in the box:

This is a pre-production review sample, so didn’t include any of the production version accessories. Just the basic light, as seen here, was sent.


Taking a closer look and looking inside:

The P25 is a little longer than some single 18650 lights due to the side switch/USB charger section between the head and battery tube. This extra length makes it possible to take a very firm tactical grip and not end up pressing the side switch accidentally. It also makes it work ergonomically allowing your thumb to rest over the switch naturally.


The model’s designation and name are laser etched into the flat areas on each side of the battery tube.


Either side of the switch section, there are heat-sink fins which also form a Picatinny rail which allows for various ‘tactical’ configurations when gun mounted.


Tail standing is just about possible, but is unstable, thanks to the design of the tail-cap.


A typical coiled spring negative terminal


The tail-cap’s standard threads are fully anodized.


The threads at the head end of the battery tube are near-square cut and bare aluminium.


The battery tube wall thickness appears substantial, but further along the tube the thickness is machined down.


Inside the head is an unusual ‘feature’ positive terminal, with physical reverse polarity protection. This requires a button top cell to work. Flat top cells will not work in the P25. The clever part about this terminal design is that the positive terminal is still sprung (so being good for shock protection) but still has the physical reverse polarity protection thanks to the contact disk being mounted on the end of the spring.


Visible as a ring of light around the side switch button, the P25 has a blue indicator light showing various statuses.


Here one of the low battery flashes has been captured while the P25 is on.


On its ‘Lower’ output setting.


The P25 is fitted with an XM-L U2 LED and smooth reflector.


To protect the built in charger port, there is a well-fitting rubber cover. The tab to open it is close fitting to the body.


The Micro-USB charging port revealed…


…and the USB cable plugged in.


Modes and User Interface:

Having combined a forward-clicky physical tail-cap switch with a micro-control-unit (MCU) operated by a two-stage camera shutter style side button, NITECORE have given the P25 a uniquely flexible user interface.

The tail-cap switch acts as the master power switch. If it is OFF, the P25 is OFF.

The forward clicky switch allows momentary use of the output mode last selected by the MCU.

Then, with the tail-switch ON:

The two-stage side switch allows the following:

Turning the light ON and OFF/Standby with a brief full press.

In Standby mode:
- the indicator light flashes as a beacon.
- a brief half press will activate the battery voltage readout
- a brief full press will switch the light ON

When ON:
- A brief half press will cycle through the output modes (Lower-Low-Mid-High-Turbo)
- at any point holding the button halfway will switch to Turbo
- a full press and hold will enter the flashing modes
- in the flashing modes a brief half press cycles through (Strobe-SOS-Beacon)

With the light ON, as the battery gets low, the indicator lights starts to flash as a low battery warning.

The indicator light also shows the state of charging with the powered UBS cable attached:
Flashing rapidly – problem (possibly the tail-switch is not ON)
Flashing twice per second – charging normally
Steady on – fully charged

Batteries and output:

With a choice of 1x 18650, 2x CR123 and 2x RCR123, the P25 has good flexibility.

The built in li-ion charger will only charge 18650.

As the P25 has a built-in charging function, I thought it was only fair to test the output using a 18650 charged by the P25 rather than an external charger. After completing the charging (indicated by the charge light going on steadily – it flashes twice a second during normal charging) the 18650 cell measured 4.14V, so achieving a pretty reasonable state of charge and one at which you could happily keep topping up to without excessively shortening the battery life.

With the built in charger, the tail-cap switch must be on for the charging to work. If you leave it off, the charge light flashes rapidly indicating a problem.

As well as a 18650 cell charged by the P25, the testing was also carried out with primary CR123 cells.

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 P25 on 18650I.S. measured ANSI output LumensPWM frequency (Hz)

Strobe runs at 8.7Hz

Neither CR123, nor IMR 18650 delivered better results.

In Standby mode, there is parasitic drain to consider. Having logged this drain, there is a background 601uA drain which spikes to 1mA when the indicator beacon flashes. This spike is so brief the logging was hardly able to see it, so as far as an average drain current, it is going to be not much more than the steady 601uA. At this drain a fully charged 18650 should last 0.59 years. With the master lock-out provided by the tail-switch, this drain becomes insignificant. It is good to see that the drain is still reasonable if you chose to leave it on Standby.

On a Turbo runtime test, after 20mins on Turbo the P25 automatically switches back down. Here I have switched it back onto Turbo every time it switched down. (the last lower dip was caused by me fumbling the switch back to Turbo and accidentally switching it to Low before back up to Turbo).

Once full Turbo cannot be maintained the output no longer switches down and instead gradually declines.


In The Lab

NEW for Winter 2012 ANSI standards include maximum beam range. This is the distance at which the intensity of light from an emitter falls to 0.25lux (roughly the same as the lux from a full moon). This standard refers only to the peak beam range (a one dimensional quantity), so I am expanding on this and applying the same methodology across the entire width of the beam. From this data it is possible to plot a two-dimensional ‘beam range profile’ diagram which represents the shape of the illuminated area.

In order to accurately capture this information a test rig was constructed which allows a lux meter to be positioned 1m from the lens and a series of readings to be taken at various angles out from the centre line of the beam. As the rig defines a quadrant of a circle with a radius of 1m, all the readings are taken 1m from the lens, so measuring the true spherical light intensity. The rig was designed to minimise its influence on the readings with baffles added to shield the lux meter from possible reflections off the support members.

The distance of 1m was chosen as at this distance 1lux = 1 candela and the maximum beam range is then calculated as the SQRT(Candela/0.25) for each angle of emission.

In this plot, the calculated ANSI beam ranges are plotted as if viewed from above (for some lights there may also be a side view produced) using a CAD package to give the precise 'shape' of the beam.

With its large smooth reflector, the P25’s beam is more of a thrower so the spill is quite narrow and not that bright.


Zooming out to the 5om grid shows the full extent and shape of the beam’s range.


The beam

The indoor beam shot shows the bright hotspot of a thrower and the relatively dim spill. Beyond the spill’s outer edge it is hard to see much.


Outdoors shows the P25’s strength as a thrower, but one with a good sized hotspot.


What it is really like to use…

In designing the P25, NITECORE could be accused of putting together all of their other design features into one light, just for the sake of it. However, despite having seen all these features in other NITECORE lights, they have been combined in a very useful way, and one which I’ve found to work very well.

The two-stage side switch can take a little getting used to, but operates very precisely (which is good considering this is part of the Precision Series) and the two stages are easy to feel. The full press is a very positive click, and the half press has its own distinct feel.

The side switch and its Standby function with flashing beacon, is very intuitive to operate. But left in this Standby mode, suffers from parasitic drain. OK, the drain on the P25 is nice and low, but it is still there. But wait…., the P25 has a physical switch to lock-out the light completely.

The inclusion of this physical switch not only eliminates any parasitic drain, but also has been implemented to give a very useful function, that of momentary tactical operation (of whichever MCU output has been selected, including strobe modes).

To be truly tactical, a light should be simpler. The P25, in a stressful situation, and in the hands of a ‘grunt’ (term used in the most respectful way), is probably not going to work. However, in normal conditions the P25’s design makes it fun to use, and the controls are ergonomic and simple enough.

I’m not convinced about the true usefulness of the Picatinny rail cooling fins, but whether you use them for this function, or simply appreciated the styling they give the P25, I think you’ll like them.

Although the rubber charger-port cover is very low profile, this has been catching on the holster I have been using (the sample did not include the P25’s proper holster). The rubber itself is quite grippy, which is why is has ‘rolled up’ when being pushed into with the holster. As this will compromise the waterproofing you need to be aware that the rubber cover can catch and come loose. This may not happen with the NITECORE holster, but I don’t have one to check it with.

Having the built-in charger more than makes up for having to check the port cover. You can top up the battery using any Micro-USB charging cable from a mains adapter, car charger, or computer port.

Being able to top up the battery in-situ is useful, and having the battery voltage readout function makes this a fantastic pairing of features. It is so easy, at any point, to check the battery voltage. You then know if it needs a top-up, or if it is not worth it. I’ve been unnecessarily checking the battery voltage frequently, just because I can.

This is perhaps only a consideration for those with larger than average hands, but the control/charger portion of the P25, which does add some length, makes the P25 a great length to grip tightly, with no accidental pressing of the side switch. This gives me great confidence that the P25 will work in a variety of different grips with no interference with the controls.

I find the P25 to be a well thought out light. It has certainly benefitted from the features NITECORE has developed in its other lights. In the P25 these features have been combined so that they integrate seamlessly and give great usability.

Test sample provided by NITECORE for review.


Flashlight Enthusiast
May 5, 2010
Hove, UK

Having recently got a USB 'Charge Doctor' I can confirm that during charging, the P25 draws 0.49A from the USB charger (which itself is rated to 2A, so can easily provide more current).
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Flashlight Enthusiast
Dec 8, 2011
Thanks for the review!
With new flashlights my main concern regarding technical details is the performance, so i find your table and graph most helpful :)


Feb 6, 2013
this is a very value for money thrower + rechargeable( mini usb) 18650 light. compact and long run time. very worth for it. did I mention it is very bright.... 1 light I put in car !!