# Fenix LD41 (XM-L U2, 4xAA) Review



## candle lamp (Aug 25, 2012)

LD41 is single XM-L U2, dual switch interface, and high-output light on 4xAA's from Fenix.












Packaging is standard Fenix cardboard box with molded plastic insert. Inside you will find the LD41, a holster, lanyard, spare o-ring, spare tailcap switch boot cover, detailed user manual, warranty card, and etc. 

*Manufacturer Specification *from user manual :

- Uses Cree XM-L U2 LED with a lifespan of 50,000 hours
- Uses four 1.5V AA (Ni-MH, Alkarine) batteries 
- 175mm(Length)x40mm(Diameter)
- 180g weight (excluding batteries)
- Digitally regulated output maintains constant brightness
- Reverse polarity protection guards against improper battery installation
- Low-voltage reminder indicates when battery replacement is needed
- Anti-roll, slip-resistant body design
- Tactical tailcap switch with momentary-on function
- Tail mode switch, one click for brightness selection
- Made of durable aircraft-grade aluminum
- Premium Type III hard anodized anti-abrasive finish
- Toughened ultra-clear glass lens with anti-reflective coating











Notice : The above mentioned parameters (lab-tested with 2500mAh Ni-MH batteries) are approximate and may vary between flashlights, batteries, and environments.
.
.










The body plan of the LD41 is fairly straightforward. The light has a cylindrical head, but has a rectangular battery tube. The rounding off the four edges of the battery tube turns into more fluid & comfortable shape to outline & grip (i.e., comfortable to hold and handle). 
Black anodizing (type III = HA) is matte finish, and without blemishes on my sample. Lettering is clearly legible in light gray, not bright white.
.
.





The light has mainly 2 parts (i.e. head and battery tube). There is a quality battery carrier as well.
.
.





There is "hot surface" warning on the head, and you will see the positive and negative contact on the back of the head. The light uses a fairly good smooth reflector, with reasonably deep proportions for the size of the head. There seems to be very mild texturing applied to the reflector surface which slightly dulls the finish, so I would expect reasonable throw with no doughnut-ring (Let's see it later on). Cool white XM-L U2 emitter is well centered on my sample. The light uses AR coating lens and the purple hue is reflected on it.
.
.





The crenellated bezel allows light to easily see if the LD41 is on when stood on its head (i.e., bezel down).
.
.





The light lacks knurling to speak of on the light, and instead has a large number of tiny ridges along the both narrow sides of the rectangular battery tube. While this helps a bit with grip, I think the light somewhat slippery overall, but it isn't slipperier than expected.
.
.





There are the positive and negative contact springs on the head, and are the circular negative contact plate surrounding the central positive contact plate on the battery carrier.
.
.















The light uses a battery carrier to hold the 4xAA cells. Quality seems good, but note that all the material is translucent plastic, aside from the contact plates and springs. But the carrier seems reasonable quality.
.
.





Batteries fit securely within the carrier, so they don't have a tendency to pop out easily, thanks to the well-made half-circled groove & small pieces in the middle of the carrier. There is absolutely no battery rattle inside the light if I shake the light laterally when it's fully loaded. The 4xAA cells are arranged as two in series, for each of the two channels of the carrier - the two channels are in series. So the battery carrier has a 4S with 2x2 layout. 
.
.





Inside of the battery tube you will see there is a V-shaped notch along the tube. This corresponds to the groove visible on the battery carrier (i.e., you have to line up the groove on the battery carrier with this V-shaped notch during inserting the carrier). This is the only one way to insert the carrier. 
.
.





The LD41 uses dual switches interface in the tailcap to control on-off and mode changing.
When seeing from the head to the base of the battery tube, you can see the larger rubber switch boot and the smaller rubber switch boot with a very small white plastic rod. (i.e., the battery tube only holds the switch rubber boots.) If you assemble the carrier & tube, the larger rubber booth and the smaller rubber booth with a plastic rod are linked to a mechanical (or physical) on-off clicky switch and a electronic mode changing switch on the battery carrier respectively.
.
.










The light has a reasonable number of anodized thick trapezoidal (nearly square-cut) screw threads (i.e., they should be durable and stable) at both head and battery tube, but that doesn't really matter too much to head lock-out since the current is carried through the battery carrier only and the negative spring contact is protruding. However lock-out is still possible, turning the head one and a half turns to the left on my sample. 
.
.





There are 4 external screws tightly fixing the aluminum tailcap - which holds the switch rubber boot - to the battery tube. and the screws seem good quality. 
The on-off switch is a forward clicky switch, and has a good feel but slightly stiffer than expected. The mode changing switch produces a definite but much quieter click sound & minimal travel than the on-off switch when pressed. The switches are intuitive, and work well.
.
.





The tailcap has four partially raised rims which provides comfortable activation of the switch. There is a slit through a rim which allows for lanyard attachment. 
The light can tailstand, but there is a bit wobble, as the larger on-off switch does protrude out the tail end slightly on my sample
.
.





The gripability & handling the light is reasonably good.

The *overall build quality *is very high.
.
.





From left to right : Eneloop AA, Fenix LD10, Fenix E21, Fenix LD41, Fenix TK50.
.
.
*Measured dimension & weight
*




.
.





The LD41 comes with a basic nylon holster with a velcro strap on the head. The light fits in the holster either head-up or head-down. 
.
.
*User Interface

*On-off is controlled by the larger forward clicky switch (press-on for momentary, click for locked on), and mode changing is controlled by the smaller electronic switch. There are two modes (i.e., general mode & flashing mode).

1. General mode
Output changing is controlled by the smaller electronic switch. Click and release to advance through output modes, which proceed in sequence from Low -> Med. -> High -> Turbo, in repeating sequence. The light has mode memory, and remembers the last output level used when you turn the light off and back on, (even after a battery change). 
You can't set the output level while the light is off. The electronic switch only works when the light is powered on by the on-off switch first. 

2. Flashing mode
The Strobe is accessed by pressing and holding the smaller switch for more than about 1 sec. To access SOS, press and hold the smaller switch more than about 3 sec. To return to the general mode, just click the smaller switch once, or turn off & on the light. The flashing mode has no memory. The light always turns on in the memorized general mode, so there is no danger of strobing accidentally (also it means you can't directly access strobe without turning on the light in general mode first).

User Interface is good, and I like seeing the flashing mode well hidden.
.
.
*Overheating Protection
**
*After 30 mins of continuous runtime on Turbo output, LD41 drops down to Hi output for the rest of the time to avoid overheating the light. If Turbo is needed for extended run time, just turn off and on the light during working on Turbo or press the smaller switch once after dropping down to Hi. 
.
.
*Standby Current Drain**
*
There is no standby current because the electronic switch only works when the light is turned on by the on-off switch first. 
.
.
*PWM
**
*No sign of PWM at any level of the light, leading me to conclude the light is actually current-controlled as claimed. I notice there is neither buzzing sound nor tint-shift at all output levels with the naked eye on my sample.





.
.
*Runtime
**
*1. 4xEneloops AA






The runtime for 10% output of Turbo is appr. 310 mins in my test.
.
.
2. 4xEnergizer AA






The runtime for 10% output of Turbo is appr. 364 mins in my test.
.
.
3. 4xEneloops AA, 4xEnergizer AA






The above runtime labelled as "Trubo-Acc." is an accumulated runtime for turbo output. 
Regulation is maintained very nicely through Turbo on both batteries (Ni-MH, Alkarine). 

The LD41 steps down on turbo to High after 30 mins runtime, on both 4xEneloop's and 4xEnergizer's. This is a timed drop-down, not a thermal sensor feature to avoid overheating the light. As with the other Fenix lights, the regulation pattern and runtime efficiency of the current controlled circuit seems excellent.

*[*Update : Aug 30*]* There are always three distinct step-downs (i.e., Turbo to High, High to Med., Med. to Low) at the stage of battery depletion. I couldn't see there was flashing or blinking to indicate low voltage on low brightness level for hours, so turned the light off. The manual says _"the circuit is programmed with a low voltage protection function. If low voltage is detected, it will enter into the low brightness level, it will blink three times a second every 5 minutes. To allow normal use, LD41 will not turn off automatically and will continue to work until the batteries are depleted."_ This tells why I couldn't see blinking to indicate low voltage on low for hours. *[*Update : Aug 30*]*
.
.
*Beamshot**
*
1. White door beamshot (about 50cm from the white door)
- ISO100, F/3.5, 1/100sec, Auto white balance 






- Turbo
.
.





- High
.
.





- Med.
.
.





- Low
.
.





There is something of a greenish tint-shift in the corona around small hotspot, but it's not noticeable except up-close. The overall beam quality is good (i.e., No rings in the beam). 
.
.
2. Indoor beamshot (about 7m from the target)
- ISO100, F/2.8, 1/3sec, Auto white balance






- Turbo
.
.





- High
.
.





- Med.
.
.





- Low
.
.




.
.
3. 55m Outdoor Beamshot 
- ISO100, F/2.8, 1sec, Auto white balance






- Control shot
.
.





- Turbo
.
.




.
.
4. 60~65m Outdoor Beamshot
- ISO100, F/2.8, 1sec, Auto white balance






- Control Shot
.
.





- Turbo
.
.





The light has a reasonable amount of throw, and a nice transition from spot to spill.
.
.
* LD41 was supplied by Fenix for review.


----------



## kj2 (Aug 25, 2012)

Thanks  one great light.


----------



## sbbsga (Aug 25, 2012)

Great review!

I purchased two of this as gifts for my uncles, was thinking of getting them Jetbeam PA40 since I am happy with mine but the UI may be a little tricky to them. Still waiting for the Eneloops and chargers to arrive before giving them the surprise. I am amazed by how well it feels in my hand despite not appearing as such - a bit jealous now. My only gripe is tail standing is wobbly.


----------



## moldyoldy (Aug 25, 2012)

Agreed, a high-quality design and build light. After living with the first copy, I eventually purchased two more - keeping two and gifting one. Very consistent LED color and beam pattern. 

The beam pattern reminds me of the TK35 which has probably the best combination of spill/spot of any of the lights I have had in my hands, and I kept a TK35 also. Why both of them? So that my family does not have to deal with 18650s. They can handle AA cells w/o a problem. As the lumens increase on AA-based lights, I am trending back to them, but only those with lumens ~200 and above. 

Where do I use them? A car light for one location. The LD41 handle shape could probably break a car window in a pinch. The 500+ lumens satisfies my more common lumen needs - critters in my backyard and in the trees arguing with each other - mostly racoons. but also to pick up the foxes, etc loping thru my yard hunting for stray cats. 

For the 2-legged critters, I have a T60 waiting, if necessary backed by 12ga persuasion. Although I am an ex-mil, I strongly prefer 2000+ lumens, maybe in strobe, on a perp rather than racking a 12ga which is a sound no one wants to hear. The real-world results are almost the same (they leave in a panic), but the consequences of actual use are very different. I already used a Fenix PD30 to dissuade some car thiefs from further attempts at breaking in to my daughters' car.


----------



## tobrien (Aug 25, 2012)

i like your indoor beamshots!


----------



## Swedpat (Aug 26, 2012)

Thanks candle lamp for the review! :thumbsup:

If I already didn't get Jetbeam PA40 I would order LD41. Almost 2 hours total runtime on turbomode with Eneloops and ~50min with Energizer alkalines is actually pretty good. Energizer L91 will likely provide around 3 hours, I guess.


----------



## candle lamp (Aug 26, 2012)

Thanks and glad you're enjoying the light & the review.



kj2 said:


> Thanks  one great light.



Thanks too. 



sbbsga said:


> I purchased two of this as gifts for my uncles, was thinking of getting them Jetbeam PA40 since I am happy with mine but the UI may be a little tricky to them. Still waiting for the Eneloops and chargers to arrive before giving them the surprise.



It would make a nice present. Your uncles will love the light & Eneloops with a charger a lot. 



moldyoldy said:


> They can handle AA cells w/o a problem. As the lumens increase on AA-based lights, I am trending back to them, but only those with lumens ~200 and above.
> Where do I use them? A car light for one location. The LD41 handle shape could probably break a car window in a pinch. The 500+ lumens satisfies my more common lumen needs - critters in my backyard and in the trees arguing with each other - mostly racoons. but also to pick up the foxes, etc loping thru my yard hunting for stray cats.



Agreed. It's good for men and women of all ages to use AA sells with ease. Wow! you can see the racoons, foxes, etc in your backyard. I envy you. 



tobrien said:


> i like your indoor beamshots!



You like flowers. 



Swedpat said:


> Almost 2 hours total runtime on turbomode with Eneloops and ~50min with Energizer alkalines is actually pretty good. Energizer L91 will likely provide around 3 hours, I guess.



I expect Energizer L91 will give more runtime thanks to its larger capacity (around 2900mAh ?).


----------



## candle lamp (Aug 30, 2012)

I've just updated *[*Aug 30*]*.

There are always three distinct step-downs (i.e., Turbo to High, High to Med., Med. to Low) at the stage of battery depletion. I couldn't see there was flashing or blinking to indicate low voltage on low brightness level for hours, so turned the light off. The manual says _"the circuit is programmed with a low voltage protection function. If low voltage is detected, it will enter into the low brightness level, it will blink three times a second every 5 minutes. To allow normal use, LD41 will not turn off automatically and will continue to work until the batteries are depleted."_ This tells why I couln't see blinking to indicate low voltage on low for hours.


----------



## xlight (Sep 12, 2012)

Great review.


----------



## candle lamp (Sep 14, 2012)

xlight said:


> Great review.



Thanks for the compliment, in spite of my lack of English.


----------



## tobrien (Sep 14, 2012)

candle lamp said:


> Thanks for the compliment, in spite of my lack of English.



your posts have always struck me as having had pretty good English. you're doing fine!


----------



## candle lamp (Sep 15, 2012)

tobrien said:


> your posts have always struck me as having had pretty good English. you're doing fine!



Many thanks for the support. tobrien! :thanks:


----------



## tobrien (Sep 15, 2012)

candle lamp said:


> Many thanks for the support. tobrien! :thanks:



any time buddy!


----------



## Swedpat (Sep 21, 2012)

My curiosity made me get this light though I first didn't think I would get it.
Yesterday I received LD41. Short impression: the shape of the handle provides very nice hold. It's as well throwier and brighter than my Jetbeam PA40W, but according to ceiling bounce lux test it's not as bright as my Surefire P2X Fury, despite higher claimed lumens(yes, we know the Surefire lumens...). The tint is very cool but still acceptable. 
Because Jetbeam PA40W is a very similar competitor I would say(have no experience of the cool option): for shorter distance PA40 is better, also the tint is more comfortable. 
LD41 has low-mid-high-turbo order, which is better than the highest mode first of PA40, in my opinion. 
LD41 is a powerful 4AA light and the only serious drawback I(instantly) can find is that while the design of the tailcap is like made for a perfect tailstanding the button protrudes (even when the light is on). It's still tailstandable, but wobbly. Why in the world Fenix makes such a miss? However, I think this is a great light!


----------



## candle lamp (Sep 21, 2012)

Good to hear you've got the light.

Many thanks for your detailed feedback. Swedpat! :thumbsup:


----------



## tygger (Sep 23, 2012)

Great review Candle Lamp! LD41 has very good runtime on eneloops. :thumbsup:


----------



## candle lamp (Sep 25, 2012)

tygger said:


> Great review Candle Lamp! LD41 has very good runtime on eneloops. :thumbsup:



Thank you. tygger!

Yes, Eneloops show good runtime, similar to other lights have good controlled-circuit.


----------



## FireWire (Feb 7, 2013)

My ld41 works great as a bike light. I use the TwoFish CycleBlock. £9 from amazon 










Thank you


Kindest Regards






___________________________


----------



## candle lamp (Feb 7, 2013)

FireWire said:


> My ld41 works great as a bike light. I use the TwoFish CycleBlock. £9 from amazon.


That's a good information for those who has the light including me. Thanks a lot. FireWire! :thanks:


----------



## steveg270 (Feb 8, 2013)

Just an FYI for owners of this light. I had been looking for a few months for a diffuser for this light. I decided to make a post on CPF asking for help. As always you guys came to my defense and I was told that Fasttech.com sells one for less then $2.00 that fits 39-43mm head (so they claim ) the LD41 is 40mm. I ordered it and hope it fits good. I have not gotten it yet . Anyway just thought I would mention it because they are hard to find in that size.


----------

