[Review] FENIX UC40 Ultimate Edition (XM-L2 U2 / Rechargeable,1x 18650 / 2x (R)CR123a)

FENIX UC40 Ultimate Edition
Battery: Proprietary / 1x 18650 / 2x ®CR123
Modes: 4 (Low, Med, High, Turbo) + hidden Strobe
Switch: Electronic, head.
Date: May 2014
FenixLinternas / Fenix Global / RdL / ForoLinternas

The new Fenix UC40 Ultimate Edition is the new commitment of rechargeable flashlights by Fenix. It is a compact size flashlight, similar to the E35 or PD35, where it’s integrated charging port and its own battery and has all the attention.

This Ultimate Edition differs from the basic version of the UC40 model, which uses a different LED, being on the Ultimate Edition (UE) a XM-L2 U2 versus the XP-G2 R5 of the basic version, with obviously great differences in the maximum output for the XM-L2.

The flashlight comes in a cardboard box in which Fenix has included, in addition to the flashlight, a USB -> MicroUSB cable, rechargeable proprietary battery, wrist strap, o-ring spare kit, and the usual documentation incl. user manual and warranty card.

FenixLinternas (exclusive Fenix distributor for Spain, Andorra and Portugal) has included along the UC40UE a USB power adapter for wall socket ( EUR) and a Fenix holster for the flashlight, both accessories not included in the set of origin but according to the comments from the national retailers all will be included in the price when ordering this model from their website.

The external appearance of the UC40 Ultimate Edition is simple and sober, with quality details as usual in the flashlights from this brand. The flashlight is machined aluminum with an excellent black anodized finish without flaws or imperfections with the classic matte touch on the porous hard anodized surface.

We found different laser engravings on the body, all very well defined and easy to read thanks to the high contrast with the black background.

The flashlight head has a smooth bezel, with no crenellations, in which optics we have a glass lens with anti–reflective coat, smooth reflector and XM -L2 U2 correctly centered on its bottom.
Interestingly, the head of the flashlight is built into the body, and as usual the bezel comes sealed, the only removable part of this UC40UE is the tailcap.

Outwardly, the base of the head has four heatsink fins with oval profile, which while increasing their ability to exchange temperature in this critical area, provide anti-roll function preventing the flashlight from rolling free on smooth surfaces.

Between the cooling fins it’s found the electronic switch, single and unique flashlight switch under a silicone coating with symbol “mode change” seen in other flashlights from this brand. The switch feel is good, and is easy to locate its position thanks to protrude slightly from the profile of the fins.

The torch body is coated with a peculiar knurling , similar to that found in TK75 battery barrel, and which is formed by small rectangles , which in are finned smoothly , which results in an optimum grip without using the classic diamond partner knurling. Personal and original design.

The threads , as is customary in Fenix , have the trapezoidal cut and are anodized except at its base , which allows the use of common primary or rechargeable batteries (more on this in the User Interface section).

The tailcap prescind from any mechanical or electronic switch, and houses inside the charging system for the Fenix battery. Outwardly, in its flat base that allows the flashlight in place solidly tailstand there is the charging port, standard microUSB, protected by a silicone plug. Alongside this, we have a small charge status indicator LED, which also notify us when the voltage is low and battery recharging is required. Inside, we find the particular battery contacts, compatible for both UC40UE own battery (which it is provided with the two polarities at both ends) as well as common 18650 or CR123A batteries.

Finally, we have the rechargeable battery included with the flashlight. It is a battery of a slightly larger size (20mm x 73mm) to common 18650, which is built with a Panasonic NCR18650B cell inside (3400mAh), along with a protection circuit and contacts that make compatible with the charging system.

The battery has contacts for both polarities at both ends, the center positive and negative on the outside, being separated by a plastic ring. The battery comes installed in the flashlight, isolated by two plugs on the positive pole of either end. Therefore, the battery orientation is irrelevant when inserting it in the UC40UE.

The UC40UE has a simple and intuitive interface, in that simplicity takes center stage and selection of modes and turning on and off the light is made from a single electronic switch.

  • On and Off: To turn on the flashlight is necessary to keep the switch down for half a second. To turn off, perform the same operation.

  • Modes: With the flashlight on, simply click switch the toggle between the 4 main flashlight modes, in ascending order: Low - > Mid - > High -> Turbo
    Memory: The flashlight remembers the mode in which we turned off and will return to this in the next activation.
  • Strobe Mode: The only special mode this is UC40UE includes is a variable frequency strobe mode, which also has a function for quick access. Both with the flashlight on or off, just hold the button down for more than one second to enter this mode. The strobe mode has no memory, so when you turn the flashlight off in that mode and then on again, it will go to prior access to strobe mode.
  • Mechanical block-out: With its anodized threads, the Fenix UC40UE can be blocked by partially unscrewing the tailcap threads. This will avoid an accidental or inadvertent activation, but only when we use common batteries because the proprietary battery itself has both polarities at both ends, and flashlight lights up even without the tailcap installed. Logically, as the light lacks a mechanical switch it has a parasitic consumption when off, about 500uA ( 0.5mA ), which will completely discharge a 3400mAh battery (included) in about 280 days, or what is the same 9 months. Not surprisingly Fenix, in the user manual, recommends a full charge every four months, regardless of the state of charge.
  • Low Voltage Warning: Using the LED next to the charging port on the UC40UE tailcap, the flashlight notifies us through red flashes when the battery level is low and that need a recharge.

  • Charging system: First, point out that the charging system built into this flashlight is only compatible with its own battery, included with the flashlight. This is because the charging system uses a system with both polarities at the same end of the battery, making it impossible charging common 18650 batteries. The microUSB port which has endowed this Fenix UC40UE provides an excellent feature and it is compatible with most chargers for smartphones or tablets, allowing recharging our flashlight where we recharge our mobile devices. The integrated charger needs just over six hours to charge the included battery (built with a 3400mAh Panasonic NCR18650B cell inside). The light next to the charging port changes from steady red to steady green when charging is complete.

(All measurements are taken following the ANSI NEMA FL1 procedure, using the highest reading of between 30 and 120 seconds after activation. More details in my ForoLinternas thread)

The four UC40UE modes have an excellent distribution, with a minimum 10LM mode and 960LM maximum. The test in the integrating sphere is again offering more than satisfactory results, with excellent agreement between specified by the manufacturer and measured by the photodiode.

As expected, this UC40UE Turbo mode has a time-controlled stepdown, which reduces down to High mode after three minutes of continuous usage. We found another stepdown, this surely voltage controlled, at about two hours now stepping down to Medium mode, and thereby remaining regulated by another two hours and 45 minutes, where the flashlight finally jumps to low mode, and quickly loses regulation. The complete sequence exceeds four and half hours regulated output with excellent linearity in all stages.

To better observe the performance of the Turbo mode before stepdown, I have slightly modified the graph to limit it to 5 minutes. I was pleasantly surprised to see how, though a relatively compact flashlight is able to maintain in amazing way that enormous output of more than 1000LM for three full minutes. Undoubtedly, the dissipation design of this flashlight is more than successful.

Compared to other flashlights, the UC40UE shows an excellent power/runtime thanks to stepdowns sequence.

Again, I go back to modify the graph to see the detail now for the first ten minutes of the comparison.

Note: To obtain comparable data, all measurements were obtained using a 3100mAh Panasonic NCR18650A battery instead the included 3400mAh.

With a head diameter and reflector size very similar to several flashlights, such as PD35 or E35UE, the UC40UE has very common beam profile. A smooth reflector of about 20mm diameter and not too deep produces a classical projection clearly floody, but without losing decent throw thanks to the smooth finish of the reflecting surface, so the brand spec’ed 10404cd and 204 meters range.

The tint of this unit is pretty good, being cold white with a very slight greenish trend especially in the corona surrounding the hotspot.

Within the current available rechargeable models, this UC40UE seems to have several strengths, but also some weak points. The mechanical finish is excellent, Fenix quality. Modes and user interface are also hallmarks of the brand as well as its performance and efficiency.

Fenix UC40UE • Nitecore P12 • Fenix PD32 • Eagtac TX25C2 • Nitecore EC2

Negatives: While this charging system barely contributes to the package size, I think it would have been a great feature to allow also recharge regular 18650 batteries, and not just the proprietary. I also see with some concern as Fenix forget again implement a blocking system, especially critical in lights lacking mechanical switch (in this case , only for the included battery which is impossible to block out both accidental activation or parasitic battery drain).
Positives: Undoubtedly the biggest attraction of this Fenix is its rechargeable autonomous system, and I think Fenix has nailed it when integrating a microUSB port for this purpose, making the flashlight compatible with most chargers and cables we already have for our everyday mobile devices such as smartphones or tablets. I also liked that for the rechargeable battery has used a base of proven quality battery, the today’s best I would say. Its user interface is simple, easy and intuitive, controlling everything with one single switch, located in the head. Its size and weight is not the smallest segment, but are comfortable and balanced for everyday professional or occasional use. The output of the three minutes of Turbo mode is surprisingly high, so that the LED internal dissipation design is definitely a success. The regulation of the modes shows an amazing linear regulation, as is customary in most Fenix flashlights. Beam profile is clean and versatile, perfectly spaced modes, a great rechargeable flashlight.

Great review, thanks!

+ 1

Thanks UPz. Nice review on a nice light.

Thank you guys!

I’m thinking if i should get this or E35UE……

E35UE has momentary turbo, this UC40 has momentary strobe.
If the rechargeable feature is not needed, E35UE is smaller.
It is all up to your needs or likes.

Yes i know the features, just need to decide what i need more flood or throw, but i think i want a small flooder more :smiley:

Does this superlong protected 18650 fit too? :)

And can it also be recharged in the flashlight yes?

Hi pipifax,

Yes, long protected batteries fit without troubles. The Fenix battery is 20mm x 73mm, so those common ~70mm long protected NCR’s fit with no problems.


Its a pity you edited this post to include the question about the charging system and the Panasonic batteries as UPZ had already answered the first half of your question so he might not see the edited part.

The answer appears to be no, you must use the oddball Fenix battery if you want to use the charging feature…


Thanks for the review on this very well thought-out light. I would immediately buy it if the led was a nice neutral, or if is was an easy swap (which it never is with Fenix lights).

HKEquipnet sells for 70.99 USD!
PM me for a Code :wink: