Fenix FD40 LED flashlight review

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Fenix FD40-10

My name is Andy, and I’m a Flashaholic.  I have a lumen problem.  Ever since my first “cool” flashlight 30 years ago, the MagLite, I’ve been chasing the next go-to handheld torch.  This illumination arms race has only escalated in the past 15 years with the introduction of better and brighter LEDs.  Today I’ve got the latest from Fenix that has something my MagLites of yesteryear had- an adjustable focus.

Fenix FD40-01

Remember the original MagLite?  You could twist the head and adjust the beam from a wide flood to a narrow spot.  The Fenix FD40 features an adjustable focus as well as a 1000-Lumen beam from a Cree XP-L HI LED.

  • Length:  5.1 inches/130mm
  • Tube Diameter:  1.3 inches/32mm
  • Head Diameter:  1.8 inches/45mm
  • Weight (excluding batteries): 5.6 oz./159 grams
  • Twist head to adjust focus: 78 degrees for flood; 40 degrees for spot with a 7.5-degree center beam
  • Spotlight maximum beam distance:  984 feet
  • Stainless steel side switch
  • New Lock-out function to prevent accidental activation
  • Standard tripod mount in body
  • Flat tail cap for tail standing capability
  • Digitally regulated output maintains constant brightness
  • Over-heat protection to avoid high-temperature of the surface
  • Intelligent memory circuit, automatically enters previously used brightness level when turned on again
  • Reverse polarity protection to protect from improtper battery installation
  • Made of durable aircraft-grade aluminum
  • Premium Type III hard anodized, anti-abrasive finish
  • High efficient lens with total reflective coating
  • Waterproof to IPX-8 rating, under water 6.56 feet for 30 minutes

Fenix FD40-23

Fenix FD40-27

There seems to be a discrepancy between the published runtimes and those in the printed manual.  The FD40 can accept the 18650 battery or the larger 26650 one, which has greater capacity.  It is reasonable to believe that the runtime for the larger 26650 battery (red arrow, below) would be longer than the smaller 18650 (green arrow).

Fenix FD40-02

In the package you get the PD40 light, one lanyard, one holster, spare O-ring, manual and warranty card.


Fenix FD40-21

Fenix FD40-22

If you’re familiar with Fenix flashlights, the holster will look familiar.  It’s got a hook and loop flap and a belt loop on the back.

Fenix FD40-03

For evaluation, I was sent the Fenix ARE-X1 single battery charger and the Fenix ARB-L2S, a 3400 mAh lithium ion, type 18650 rechargeable battery.

Fenix FD40-05

The ARE-X1 kit comes with the charger and a short microUSB cable.
Fenix FD40-06

The microUSB connector is found on one end…

Fenix FD40-07

…And the full-size USB can be found on the other.  You can actually use this charger to recharge or top off your USB-chargable gadgets.  It’s like having two gadgets in one.

Fenix FD40-09

I’ve plugged the ARE-X1 into a spare iPhone charger to juice things up.

Fenix FD40-11

Size-wise, the FD40 is shorter and thicker than my current go-to flashlight, the Fenix UC35.  While the UC35 has a tail-clicky cap button for on-off and a second barrel-mounted mode switch, the FD40 has just one round button.

Fenix FD40-14

On the opposite side of the button is a threaded hole, suitable for tripod mounting.

Fenix FD40-13

There’s a lanyard hole on the tailcap.  Note that the cap is flat, so you can stand the FD40 up in “candle mode”.

Fenix FD40-12

The business end of the FD40.  Do NOT look into this end when lit!

Fenix FD40-15

Feeding time!  Twist the tailcap off…
Fenix FD40-16

…and you’ll find this aluminum spacer.  Why?

Fenix FD40-17

If you use a 18650 battery, you’ll need the spacer to assure a proper fit.

Fenix FD40-19

Here’s the 18650 battery in the barrel of the FD40, ready to go.

Fenix FD40-25

On the left is the skinnier 18650 battery.  On the right, the 26650.  (I bought the 26650 on my own and was not included as part of the evaluation kit)

Fenix FD40-26

As you can see, the larger 26650 is a perfect fit.  No spacer necessary.


Fenix FD40-24


OK, so how bright is it?  How well does the adjustable focus work?  To try this, I set up this ridiculous rig with my Fuji X-E2 (see link to Mark’s review).

Fenix FD40 vs UE35

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I was curious to see how it would compare to my old Fenix UE35, which had a less concentrated center.  The FD40 produced a much more “round” circle of light.  Both lights at the brightest setting.

Fenix FD40 spot vs flood 01

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Next I compared the FD40’s spot vs. wide “flood” beam.  It’s hard to tell from here but the wide pattern is actually quite seamless without dark spots.

Fenix FD40-hall

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Finally I clicked through all the brightness modes (Eco, Low, Mid, High, Turbo).

Oh yes, there’s also a strobe mode.  You can press and hold the button from the off mode for a few seconds and… well, don’t look if you’re prone to seizures.  It’s wicked annoying.  It will certainly get your attention.

Is it the brightest flashlight ever?  The smallest?  The largest?  No.  For me, the versatile adjustable focus and ability to use both 18650 or higher capacity 26650 batteries makes the Fenix FD40 the new ruler of my flashlight kingdom.

Updates 03/15/16

Although it’s been four months, the Fenix FD40 is still my go-to flashlight. That’s an eternity in the world of ever-changing flashlights. I think it’s the fairly compact size and adjustable focus that seal the deal for me.

Updates 05/18/16

Many flashlights have come and gone, but I still keep the Fenix FD40 on my desk as my go-to flashlight. Its large battery capacity and flood/spot beam focusing make it the ideal flashlight for me.

Source: The sample for this review was provided by Fenix Outfitters. Please visit their site for more info.


Product Information

  • 18650 or 26650 lithium ion battery
  • Adjustable focus, multiple brightness levels
  • Long runtime with 26650 lithium ion battery
  • The larger 26650 battery may be sold separately (depending on your reseller)
  • One button control has a learning curve (albeit short)
  • As with most LED flashlights, the "Turbo" mode stays on for 3 min before tapering to "High"

8 thoughts on “Fenix FD40 LED flashlight review”

  1. Gadgeteer Comment Policy - Please read before commenting
  2. As a fellow flashaholic where brighter is better, i have two Ultrafire lights. A small one that uses a single 18650 and a larger one that uses 2. Take a look at this: UltraFire® CREE 1200 Lumen XM-L T6. it is focusable which my original 1000 lumen one wasn’t. Cost me $12.67.

  3. your review is really cool. this flashlight seems nice and not very expensive. one thing i dont like it is the time stay-on. it’s a bit longer then I hope.Maybe I’ll consider purchase it. Thank you.

  4. Looks like Fenix has discontinued the FD40 for the new FD41 model. $84.95. Seems like a completely different model – it doesn’t take 26650 batteries and no longer has a Turbo mode. Brightest mode is 900 lumens now.

      1. Jeepers. Yes it has been discontinued. I missed the notice on the FD40 page Sorry. PLEASE let us edit our posts!!!

  5. This is one very nice, informative review. I’d like to know where I can buy the holster you show in this review. Is this available from the Fenix store? If so, how do I search the Fenix store for it and what model number am I looking for?

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