Reviewer's note: This is going to be a shortened "mini-review" of the Fenix LD12. It will still contain all the detailed analysis, measurement and runtimes – but will be less detailed on the background information and pics. For those looking for info on the overall light build, please check out my video overview below.
The LD12 is the current premium 1xAA model available from Fenix – and it has come a long way from Fenix's inaugural single-stage flashlight, the L1P.
Through the years, I have owned most of the Fenix line in the 1xAA battery format - through the L1T (both Luxeon III and Rebel R80 versions), L1S (Luxeon I), L1D (Cree XR-E P4, Q2, and Q5 versions, as well as Rebel R100 version), to eventually the LD10 (Cree XP-G R4). I've even had the E11 for good measure (Cree XP-E).
But what I've been missing in my nearly complete compilation has been the more recent LD12 (originally Cree XP-G R5, but now available with XP-G2 R5). I've decided to rectify that situation, and have picked up a recent XP-G2 R5 version ("125 lumens") from a local dealer. Let's see how it compares to other modern 1xAA lights.
Manufacturer Reported Specifications:
(note: as always, these are simply what the manufacturer provides – scroll down to see my actual testing results).
You can find the current XP-G2 R5 version of the LD12 for ~$52 at authorized Fenix dealers.
Fenix packaging has been fairly standard for a few years now – although I've found they've increased the specification details on the box over time (see above). Inside, you get the standard extras, similar to my LD10 review – basic wrist strap/lanyard, extra o-rings, extra tail boot cover, decent quality holster with Velcro closing flap, detailed manual, and product inserts. A titanium clip in included on the light.
As an aside, Fenix is one of the better makers for providing reliable and consistent ANSI FL-1 standard measures on their products.
From left to right: Duracell AA NiMH; Fenix LD12, LD10; Sunwayman V11R + AA extender, Zebralight SC52; Olgith S15; Nitecore EA1, MT1A.
All dimensions are given with no batteries installed:
Fenix LD12: Weight: 52.3g, Length: 99.9mm, Width (bezel): 21.6mm
Fenix LD10: Weight: 53.4g, Length: 104.2mm, Width (bezel): 21.7mm
Lumintop ED15: Weight: 59.7g, Length: 100.1mm, Width (bezel): 21.2mm
Nitecore MT1A: Weight: 54.6g, Length: 104.6mm, Width (bezel): 22.7mm
Nitecore EZAA: Weight 20.9g, Length: 85.0mm, Width (bezel) 16.6mm
Rofis ER12: Wright: 35.5g, Length: 96.2mm, Width (bezel): 18.6mm
Xeno E03:: Weight: 48.1g, Length 96.7mm, Width (bezel): 21.5mm
Zebralight SC52: Weight 39.5g, Length 79.0mm, Width (bezel): 22.6mm, Width (max) 25.4mm
The LD12 is a little larger than the LD10, due to the extra control switch in the head. Overall dimensions are still quite reasonable for the tail clicky-switch group of 1xAA lights.
For detailed comments on the overall build, please see my video overview below.
One feature I will highlight is the mode-changing switch in the head has pretty good feel for an electronic switch. It is relatively easy to locate by feel, and has a definite click, with typical traverse.
There is also an unusual metal contact clip in the tailcap now. This appears to have replaced the more common switch retaining ring mechanism (i.e., it holds the switch in place). Not sure why the change, but it will likely prevent the common issue of the retaining ring unscrewing loose over time.
Aside from these two obvious changes (and the new XP-G2 emitter), the overall build is similar to the LD10 (just longer now due to the secondary switch).
Turn the light on/off by the forward tailcap switch. Lightly press and hold for momentary, click (press and release) for constant on. Click again to turn off.
To change modes, click the electronic switch in the head while on. Mode sequence is Lo > Med > Hi > Turbo, in repeating sequence. The light has mode memory, and returns the last level set after turning the tail switch off/on.
Press and hold the electronic switch to access an oscillating Strobe mode. Press and hold again to switch to SOS. A single click exits you from the blinking modes back into constant output.
For information on the light, including the build and user interface, please see my video overview:
Video was recorded in 720p, but YouTube typically defaults to 360p. Once the video is running, you can click on the configuration settings icon and select the higher 480p to 720p options. You can also run full-screen.
As with all my videos, I recommend you have annotations turned on. I commonly update the commentary with additional information or clarifications before publicly releasing the video.
There have been concerns raised here that Fenix is using Pulse Width Modulation (PWM) on the LD12 (see this thread for example). The only way to clarify this question is with proper oscilloscope traces.
First off, I should explain that my oscilloscope setup uses an optical transducer – so my traces always reflect actual perturbations in visual output at the emitter. Many oscilloscope reports are based on electrical voltage/current differences going into the emitter (which should correlate with output, but may not look exactly the same as my actual output ones).
Below is a comparison of each of the four output modes on my sample – all shown on the same time and amplitude scale (i.e., to allow direct relative comparisons):
LD12 Lo mode:
LD12 Med mode:
LD12 Hi mode:
LD12 Turbo mode:
I will explain what is going on in more detail below, but the take-home message is that the LD12 is most definitely NOT using PWM for its low modes - but it does have a reoccurring signal present in the Med-Turbo modes in the frequency range that can be perceptible as "flicker" for sensitive individuals.
Scroll down to post #2 for a detailed discussion of what PWM is (and isn't), and what to look for in oscilloscope traces. But to summarize, PWM is never present on Max, has a constant frequency and amplitude across lower levels, has a square wave pattern, and is only variable for pulse width. In contrast, my LD12's reoccuring signal is the opposite of the PWM - it is a signal of variable frequency and amplitude, has a sine wave pattern with nearly perfect periodicity (i.e., shows constant width), and is present on the Max level but not Lo. Here's a close-up of the LD22 Hi mode:
All of the above clearly rules out PWM. Again, see post #2 for more info.
But even though there is no PWM, the visual oscillations on the LD12 are a potential problem, as their frequencies are in the known perceptual flicker range (i.e. 700-1100 Hz). That said, you may not be able to see it unaided by eye on the LD12, due to the differing waveform and amplitude of this signal.
So, the main question is can you see this signal as "flicker" on the LD12? I can only speak for myself (and this one sample), but I can only visually detect the presence of flicker on the Med mode of my LD12 (i.e., the level with the greatest amplitude and lowest frequency). It is very subtle, and much less noticeable that PWM flicker would be at this frequency and output level. I can see no apparent signs of flicker on Hi, Turbo or Lo during actual use (and I am personally susceptible to noticing flicker). And even when shinning on a fan, I can only see stroboscopic evidence on Hi and Med. But of course, your sample could vary from mine.
A secondary question is do these oscillating signals affect the runtime performance/efficiency of the light? For the answer to that, you'll have to scroll down to my runtimes section.
I will discuss the likely source of this oscillating signal in the preliminary discussion section of my review. Note that I expect the presentation of this signal may be quite variable from one LD12 sample to the next.
Before I move on, I've read that some people have also reported seeing a change in flicker when switching modes on the LD12 (i.e., not present on activation, but present after cycling modes). I do not observe that on my sample, but I do see something interesting when switching from Turbo to Lo – there is a strong flicker effect during the ramping phase from max to min output. Forgive the rather messy trace below, but it should give you the idea of what happens as you press the switch (which occurred ~75 msecs into the run below):
And here is a blow up that I managed to catch just as the switch was pressed (at ~10 msecs into the run below):
The first pulse is the standard Turbo mode oscillation, followed by the start of the ramp down to low. As you can see, the amplitude of the oscillation increases immediately during the ramp – basically, as the light ramps down to Lo from Turbo, it passes through the Hi and Med states (with their large amplitude and lower frequency oscillations). However, once the light reaches the Lo mode, output remains perfectly stable with no signal on my sample.
So while I never saw any flicker whatsoever on the Lo mode on my sample, I can visually see a clear flicker during the ramping down phase from Turbo to Lo. But again, your sample could vary from mine.
The LD12 has two "hidden" blinky modes:
The LD12 switches between two strobe frequencies – 7.2 Hz and 18.2 Hz - every 2 secs. Here's a blow up of the switching point:
The LD12 has a fairly typical speed SOS mode.
Since this is a mini-review, I've decided to forgo beamshots. But the LD12's beam doesn't look appreciably different from other XP-G/XP-G2 lights in this size. There were no significant beam rings on my sample, although I can detect the common small dark centre in the hotspot (common to many XP-G/XP-G2 lights with smooth reflectors).
All my output numbers are relative for my home-made light box setup, as described on my flashlightreviews.ca website. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.
I have devised a method for converting my lightbox relative output values (ROV) to estimated Lumens. See my How to convert Selfbuilt's Lightbox values to Lumens thread for more info.
Throw/Output Summary Chart:
My summary tables are reported in a manner consistent with the ANSI FL-1 standard for flashlight testing. Please see http://www.flashlightreviews.ca/FL1.htm for a discussion, and a description of all the terms used in these tables. Effective July 2012, I have updated all my Peak Intensity/Beam Distance measures with a NIST-certified Extech EA31 lightmeter (orange highlights).
Interestingly enough, max initial output of my LD12 (XP-G2 R5) is actually a bit lower than my LD10 (XP-G R4), despite being in essence three output bin steps higher now.
Fenix has very believable output and throw specs for their lights, which as you can see match fairly closely to my output estimates and throw measures.
But to better understand how the LD12 performs, we need to look at the actual runtimes.
There has been some concern here that the visible high frequency flicker phenomenon on the LD12 may result in lower-than-expected runtimes. But as I explained above, the oscillating signals shown on my sample are not PWM. I would therefore not expect them to affect runtimes (which are usually excellent on Fenix lights)
Given that, I was a bit concerned when performing my initial runtime tests – but I was able to quickly track down the source to a separate problem, and resolve it.
What you are looking at above at three runtime attempts on Turbo on Eneloop NiMH (using the same battery). Clearly, something doesn't look too good on the first attempt. It was actually even worse than the above runtime appears, since I am only using a 30 sec sampling frequency above (i.e., one reading every 30 secs). Here's my initial two Med mode runtimes on a 1 sec sampling frequency and time scale:
Basically, something was causing reduced output on my initial runtimes (with periodic jumps in output, as you can see on the second timescale). This produced lower overall output and runtimes than expected.
I surmised that this had nothing to do with the "flicker" effect observed on my oscilloscope traces (as that happens on a millisecond time scale, and is quite periodic). Instead, the problem on these initial runtimes looked to me like an example of some sort of intermittent contact issue. I therefore carefully cleaned all contact surfaces with high-proof rubbing alcohol and Deoxit, and re-ran the runtimes (i.e., the subsequent attempts you see above). This completely resolved the problem for the rest of testing period.
How does the clean LD12 compare to the competition?
The overall efficiency and regulation pattern of the LD12 (after a thorough clean) is consistent with a good current-controlled light.
There is certainly nothing here to cause me any concern with the LD12's performance. You can see an extended runtime compared to my LD10 (XP-G R4), for example.
UPDATE: Here are some alkaline runtimes:
My LD12 sample shows signs of a reoccurring signal in the potentially visible "flicker" range. This is most definitely NOT pulse width modulation (PWM), but it could still be potentially visible on some modes, on some samples, to some people. I am personally sensitive to flicker, but was only able to notice it visually on the Med mode of my sample. Note that the subjective flicker in this case was not as visually noticeable as true PWM of that same frequency would be (for a comparable output level). In any case, I suspect the intensity of this signal issue will be variable across LD12 samples. See my detailed comments in the Oscilloscope and Preliminary Discussion sections of this review.
My sample had contact issues that led to some by fluctuations in output and runtime. A single thorough cleaning resolved these issues for the duration of the testing period.
Max output is not any higher than my earlier LD10 XP-G R4 (but runtime has of course increased, thanks to the higher output bin on my LD12 XP-G2 R5).
1x14500 Li-ion 3.7V are not supported (i.e., standard AA cells only).
Tailstanding was completely unstable on my sample, due to the bulging switch cover.
I've long been a fan of 1xAA lights in general – and Fenix's offerings in particular. I have owned many of the various 1xAA model they have made over the years, except for the LD12 – until now.
My LD12 sample contains the new XP-G2 emitter (R5 output bin) – although in this case that doesn't translate into much of an output difference. Fenix seems to have focused on a balanced range of output levels, and has not chased higher max outputs. Indeed, steady-state output of my LD12 XP-G2 R5 is basically the same as my LD10 XP-G R4 (even though XP-G2 R5 is basically three output bins up from the XP-G R4).
The mode-changing electronic switch is the most distinctive feature of the LD12 (and a real departure from the all the earlier AA-series lights). But Fenix got the interface right in my view, with a Lo > Turbo sequence and "blinky" modes hidden away under press-holds of the switch. Personally, I'm still fine with head twisting for mode changes, but this is a good implementation of an electronic side switch.
One of my interests in picking up this new XP-G2 version of the LD12 was the concern expressed here on cpf about a pulse width modulation (PWM)-like "flicker" on this model (see this thread for example). I provide a detailed explanation of the reoccurring signal issue in the Oscilloscope section of this review. Simply put, it is not PWM, but it is potentially detectable as a perceptible visual flicker on some modes on my sample (although it doesn't seem to be as noticeable as PWM would be at those same frequencies and output levels). I know there is a lot of confusion on this point, so I recommend you scroll down to post #2 for more info on what PWM actually is.
If I were to hazard a guess, there is probably some component on the LD12 circuit that is not reliably performing to expected specs, and this is generating some variable degree of interference/noise. I've seen other examples of this before (even on current-controlled lights), although usually not so prominent. I also know from speaking with manufacturers in the past that these things can be hard to track down. In any case, I will send Fenix customer service a link to this review. Hopefully they will be able to isolate and correct the issue soon.
One challenge in these cases is that individual samples tend to be quite variable in their presentation of interference/noise. I have no idea how representative my one sample is - but there seems to be a number of flicker reports here specifically for the XP-G2 version of the LD12. If you have a sample with a visual flicker, I suggest you contact your dealer and/or Fenix to see if you can come to a satisfactory resolution. Personally, I wouldn't consider noticeable visual flicker acceptable in a current-controlled light.
Performance-wise, I am happy to report that this signal issue doesn't affect runtime - my LD12 performs as a current-controlled light should, with very good output/runtime efficiency. In terms of the minor fluctuations I saw in in output and runtime initially, those were fully resolved by a thorough cleaning. As always, this is the first step I recommend if you find any output fluctuations when running a light. But it is a little disconcerting to find a light needs contact cleaning right out of the box.
I haven't done detailed beam testing, but the beam pattern is what you would expect for a light with this size smooth reflector, driven to these levels.
I hope you found the detailed testing comparisons in this rather long "mini-review" useful.
LD12 purchased from a local dealer.