Warning: pic heavy, as usual. 
The SC52 is the latest refresh of the Zebralight line of 1xAA lights. I recall reviewing the very first Zebralight model ever produced – the 1xAA H50 (XR-E) – some five years ago now. That was more of a headlamp model though, and was followed eventually by the traditional forward-facing SC50 (XP-E) and eventual SC51 (XP-G).
The new SC52 is a XM-L-based model, with a revised build and greater output. Let's see how it compares to the earlier models, and the competition.
Manufacturer Reported Specifications:
(note: as always, these are simply what the manufacturer provides – scroll down to see my actual testing results).
The SC52 came in the standard "eco-friendly" packaging that has been standard on Zebralight for some time now. Included in the simple (but firm) cardboard box was the light with removable clip (attached, with screws), two extra o-rings, a one-page instruction sheet, and a notice about battery use.
From left to right: Duracell AA NiMH; Zebralight SC52, SC51; Foursevens Mini AA, Quark AA; Sunwayman V11R+AA extender; Nitecore EA1, SENS AA, MT1A; Rofis JR-12.
All dimensions are given with no batteries installed:
Zebralight SC52: Weight 39.5g, Length 79.0mm, Width (bezel): 22.6mm, Width (max) 25.4mm
Zebralight SC51: Weight: 37.4g, Length 80.5mm, Width (bezel) 21.1mm, Width (max): 22.6mm
Nitecore MT1A: Weight: 54.6g, Length: 104.6mm, Width (bezel): 22.7mm
Nitecore SENS AA: Weight: 26.1g, Length: 82.7mm, Width (bezel): 19.8mm
Nitecore EZAA: Weight 20.9g, Length: 85.0mm, Width (bezel) 16.6mm
Rofis ER12: Wright: 35.5g, Length: 96.2mm, Width (bezel): 18.6mm
Tiablo E2A: Weight: 45.7g, Length: 101.2mm, Width (bezel): 19.9mm
Xeno E03:: Weight: 48.1g, Length 96.7mm, Width (bezel): 21.5mm
Xtar WK25B: Weight 42.9g, Length: 102.3mm, Width (bezel): 22.5mm
The SC52 is slightly shorter overall than the SC51 (which is impressive, given that it also has a deeper reflector and greater height clearance for longer 14500 cells, compared to the SC51).
The overall build design is similar to the earlier SC5x series lights. The most obvious changes are the slightly fatter head and the ridges along the body of the light. I definitely find the SC52 "grippier" than the predecessor SC51/SC50, which were a little too smooth in my view.
Anodizing remains the typical Zebralight "natural" finish (which is a bit more gray-green than most). Note that natural anodizing can be highly variable (e.g., my sample seems lighter colored than most Zebralights I've had).
Zebralight has finally started adding model labels to this series (previously, there were absolutely no identifying labels of any sort on SC50/SC51). The "Zebralight SC52" body label is applied to a a cut-out from the ridge detail, and is very legible.
As before, the SC52 still has a flat-bottomed tailcap (slight indentation now) and an electronic control switch in their head. The switch cover has a revised textured grip, and is more recessed than previously. It also has a firmer switch feel, requiring a more definite click to activate. Taken together, these features should help reduce accidental activations even further.
Tailcap threads are anodized as before, allowing for tailcap lockout. :thumbsup: This is important on all lights with electronic switches, since there is always some parasitic stand-by current drain to allow the switch to function (scroll down for a discussion in this case). Threads seem of comparable size and thickness to the earlier SC51.
The light can both tailstand and headstand.
The light comes with a removable metal pocket clip, held in place by two regular Phillips head screws.
As before, the light has a flat stainless steel bezel ring - but the head is wider now, with a wider and deeper reflector on the SC5. Reflector also seems to be less heavily textured than before (at least on my sample, which I would consider a light orange peel – LOP). The cool white XM-L emitter was well centered on my sample.
User Interface
The Zebralight SC-lights have always had a fairly unique user interface. While it may sound a little complex when first described, it is actually quite easy to use. The SC52's interface has been tweaked and expanded slightly from the SC51, but will feel familiar to those used to Zebralight.
On/off and mode switching is controlled by the electronic clicky switch.
Basic Operation
From Off, a quick-click (rapid press-release) of the switch turns the light on in Hi. If you repeatedly quick-click without much of a pause, the light will advance to Med, then Lo with another quick-click.
A slightly-sustained press-hold-release (hold greater than 0.6 secs) turns the light on in Lo. If you hold the switch longer, the light will advance through Med and then Hi, in a repeated Lo > Med > Hi sequence, until you let go of the switch to select the level you want.
At any time when On, press-and-hold to start the Lo > Med > Hi ramp.
A quick-click turns the light off.
Advanced operation
In regular usage, there are 6 possible output modes that are easily accessible, arranged in two sets of Lo/Med/Hi levels – the primary Lo/Med/Hi, and a sub-level set. Note that you can program the second sub-set (as explained in the section below).
To switch to one of the secondary Lo/Med/Hi sub-levels when on, double-quick-click the switch in any given level (e.g., in primary Med, double-click to go to the sub-level Med). The light will remember the selection of which Lo/Med/Hi level was last used, and return to that level the next time it is access (from Off, or as part of the ramp).
For convenience sake, Zebralight refers to the primary levels as L1, M1, and H1, and the secondary sub-levels as L2, M2, H2.
Programming the sub-levels
For the secondary sub-levels, you can actually choose from multiple choices. The primary levels are fixed.
For L2, you have the choice of three different levels. For M2, you have the choice of two different levels. For H2, you have the choice of two different levels or strobe mode (note that the strobe option can't be memorized as part of the standard operation). For the sake of clarity in my tables and graphs, I have referred to the programmable constant-output modes as L2A/L2B/L2C, M2A/M2B, and H2A/H2B. End result is that you actually have 10 defined constant outputs available to you, plus one strobe mode.
To program your desired secondary sub-level, double-click 6 times in any given level. Subsequent double-clicks will now alternate you between your various choices for that sub-level (e.g. M2A > M2B, in repeating sequence). To select the desired secondary sub-level, turn the light off by a single quick-click. When you next access that level, it will be saved to your programmed choice.
I realize the programming above may seem complicated, but you can safely ignore it all and simply use the light in basic mode as a 3-stage light. Or for that matter, as a 6-stage light in two sets of 3.
Video Overview:
For information on the light, including the build and user interface, please see my new 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.
PWM
There is no sign of PWM that I can see, at any output level – the SC52 is fully current-controlled, as claimed.
Note that the early SC51 had PWM on some of the lower levels (although I believe this was eventually replaced with current-control on that model as well). I am glad to see the SC52 is fully current-controlled right out of the gate.
Some users have reported seeing a brief flicker or pulse on the lowest possible output level (i.e. L2C, in my terminology). But I have not noticed one on mine – it seems perfectly stable, on all batteries.
Strobe:
The "hidden" strobe is a relatively slow 4 Hz (i.e., more of a signalling strobe than a tactical one).
Standby Drain
A standby current drain is inevitable on the SC52, due to the electronic switch in the head. Here is how the new SC52 compares to the earlier SC50 and SC51:
SC52: 129.1 uA on 14500, 20.2 uA on Eneloop NiMH
SC51: 41.8 uA on 14500, 14.2 uA on Eneloop NiMH
SC50: 7.4 uA on 14500, 2.3 uA on Eneloop NiMH
While there has been an upward trend in standby currents over time on the SC5x series, these values for the SC52 are still quite low in absolute terms. Assuming a standard 900mAh protected 14500, and a 2000mAh Eneloop NiMH, these currents would translate into 9.5 months on 14500, and 11.3 years on Eneloop.
Certainly, the drain is absolutely nothing to worry about on NiMH. The drain is higher 1x14500 (but still not unreasonable). But as always, I recommend you lock-out the light when not in use.
Flicker Issue on 14500
Some users have also reported flickering issues on Max on 14500, but this effect can be inconsistent. Note that the only difference in output between 14500 and NiMH/alkaline is the max mode (H1) runs at a higher level on 1x14500 initially (i.e., 500 lumens). After 1 min, the light steps down to typical max mode level for standard batteries (i.e., 280 lumens). The flickering, when observed in my case, has been on this first minute of 500 lumen output only.
There has been some speculation here as to whether this is due to different 14500 chemistries, voltage or heat. I can confirm that on my one sample, it is fact dependent on BOTH battery voltage and heat.
To explain, let me show you an oscilloscope trace for the first 65 seconds of runtime - on a fully charged AW protected ICR 14500 (~4.19V right off the charger), in my standard runtime testbed with a cooling fan.
Ok, not much to see here – the first spike shows the light On signal at time=1 sec, and the second spike is the step-down to the standard H1 level at t=60 secs.
Not let's try it again without any cooling applied:
Starting ~6 seconds after activation, the light begins flickering – at a rapidly accelerating rate. This rapid flickering continued until the light stepped down at 60 secs – at which point it ceased immediately.
How about a slower spinning fan?
Ok, now you see the flickering doesn't start until much later (~20 secs in), and is much more infrequent (i.e., slowly accelerating). I increased the fan speed to my typical level after ~35 secs, and you can see the flickering stopped immediately.
On the basis of the above, you could reasonably conclude that the flickering is mediated solely by relative heat (i.e., with sufficient cooling, you can prevent it from occurring).
But here's where it gets interesting – if I re-run the test with a partially depleted cell (~4.09V according to my DMM), with no cooling applied, I get this:
:thinking: Ok, now all you see are a few flicker spikes starting at the very end the first 60 secs 500 lumen level (which again ceased immediately with step-down). Note again, there is NO cooling applied to run above.
Note also that the actual output above is no different from the earlier runs (i.e., the 4.09V battery is giving the same ~500 lumens as the 4.19V battery did). So this tells you that the effect cannot be due solely to heat (i.e., the heat in the situation above should have been the same as the earlier no cooling trace, given that the outputs were the same).
It therefore seems that there is some sort of circuit issue whereby the light responds to high heat only if the 14500 is near max capacity. On my sample at least, these two variables are intertwined – you can't say the light never flickers <4.1V (it can – but only mildly without cooling), and you can't say it always flickers >4.1V (depends on the level of cooling).
I'm not quite sure what to make of all this, and have queried it with Zebralight. They have responded to me that they are aware of the issue, and are working to resolve it. When I hear more, I will update this thread. In the meantime, if you are finding a similar issue on your SC52, I recommend you either drain some capacity off your freshly-charged 14500 cells, or contact your dealer about a replacement. :shrug:
Beamshots:
All lights are on Max output on Sanyo Eneloop AA NiMH. Lights are about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance on the camera, to minimize tint differences.
1x14500 (AW Protected 14500) Li-ion Comparison:
Beam pattern is as you would expect for a XM-L light with this size reflector – a fairly big hotspot and decent sized spillbeam. Scroll down for full output details in my tables.
Testing Method:
All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. 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 ANSI/NEMA FL-1 Standard page for an explanation 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).
As you can see above, the SC52 has class-leading output – for both standard AA and 14500 Li-ion. The max output on 1xAA is particularly impressive.oo: Throw is reasonable, given the size of the reflector.
Since I don't have a lot of comparator data on other 1xAA XM-L lights, here are some summary tables for recent 2xAA and 1xCR123A/1xRCR lights I've recently tested (mainly XM-L-based). You can directly compare the output and throw values for the SC52 in the tables above to the tables below.
The SC52's ~290 estimated ANSI FL-1 lumens on max puts it a bit under most of the max outputs of the newer XP-G and XM-L 2xAA lights I've tested. That's to be expected, given that it is easier to have a sustained power draw from 2x AA cells in series than it is a single AA (i.e., you can't drive a 1xAA light as hard).
A similar pattern can be observed for most the 1xCR123A lights – typically, these have fairly similar max outputs to 2xAA lights.
On 1xRCR, the better comparable would be the ~540 estimated ANSI FL-1 lumens I get on the SC52 on 14500 Li-ion. That puts the SC52 in much the same category as many of the recent 1xRCR lights I've tested. This is as you would expect, as there is effectively no real difference between RCR and 14500, except perhaps greater runtime/capacity on some 14500s.
Lumen Estimate Summary
As with a number of my recent reviews, here is a summary table showing what my ANSI FL-1 lumen estimates are for the SC52:
Zebralight's reported ANSI FL-1 lumen specs seem pretty consistent with my output estimates (although my estimates seem to be a bit higher at the high end, and a bit lower at the low end). Part of this may simply be variability from one light sample to the next (e.g., it is hard for manufacturers to reliably reproduce the same sub-lumen levels in every light).
I know there's been some discussion here as to the accuracy of various lumen estimates. To expand on this in the case of the SC52, I have done some additional detailed comparisons to a Fenix light in post #2. :wave:
Output/Runtime Comparison:
Let's start with standard AA cells (NiMH Eneloop, alkaline, and Energizer L91 lithium):
Ok, there's a lot of data up there. :sweat:
The general take-home message is that the SC52 is a real output AND efficiency leader on standard cells.oo: A second point is that the SC52 is typically quite well regulated (i.e. flat-regulated) on standard cells, except on max output (especially on alkaline, as expected).
It is particularly impressive to see how long the SC52 runs on the Med-Hi levels, compared to equivalent output levels on other models. To help you compare to the Zebralight specs, here is a table comparing runtimes to the ANSI FL-1 standard of time to 10%:
Like with the Zebralight lumen output specs, the ANSI FL-1 runtimes seem fairly consistent with my testing as well.
As always though, I recommend you actually look at the full runtime graphs for more info on output level changes over time. Given the range of possible regulation patterns, it is important not to get fooled by looking at just two (rather arbitrary) points from the ANSI FL-1 standard – the full graphs tell you infinitely more (as I explain on my Testing Methods page).
1x14500:
On 14500 Li-ion, overall output/runtime efficiency of the SC52 is good, and seems pretty much in keeping with other lights in this class. However, the SC52 again shows very flat-regulation – which not all of the other lights were able to maintain.
As shown in my output summary table in the preceding section, Zebralight has also done an excellent job keeping output levels consistent between standard cells and Li-ions. The only real difference is on max (H1), where the SC52 shows a higher initial output for 1 min, before stepping down to the standard cell H1 level.
Normally that would be the end of my runtime comparisons, but I have been asked to show how the SC52 compares to other classes of lights. I provided summary tables for 2xAA, 1xCR123A and 1xRCR in the preceding section, and thought I would include 2xAA below (given the comparable battery chemistry).
2xAA Lights:
(NOTE that the SC52 is a 1xAA light, and all the others below are 2xAA!)
A couple of points strike me in this comparison of the 1xAA SC52 to the 2xAA lights. The first is that max output of the SC52 is not that much lower than the 2xAA lights – but standard cells get exhausted quickly at this level. You can really see this on the alkaline graph – there is simply no way that a 1xAA light is going to be anywhere near competitive to a 2xAA light on max drive levels on alkaline.
The second point is that the very high efficiency of the SC52 on its Med levels gives it the opportunity to compete fairly well with a lot of the 2xAA lights. No, it doesn't run quite as long for comparable output, but it is surprisingly close for a 1xAA light. Again though, you are best to run the light on NiMH or L91 lithiums to see the best performance here.
UPDATE FEBRUARY 1, 2013: Upon request, I've also plotted the max output of the SC52 against common XM-L-based 1xCR123A lights in my collection:
Please note that I have plotted *BOTH* L91 lithium and NiMH Eneloop for the SC52 above. In my testing, many 1xAA lights show slightly lower max output on L91 than they do on alkaline or NiMH. I'm not sure why (maybe to do with voltage?), but it is a common observation I've noticed over the years. :shrug: In the case of the SC52, I estimate ~290 ANSI FL-1 lumens on NiMH, and ~255 estimated lumens on L91.
I suggest you compare the full curves for how the lights perform, but in general terms, the SC52 is toward the middle of the 1xCR123A pack for initial activation output levels on max. Of course, regulation on lithium-based CR123A cells is typically flatter than NIMH.
Potential Issues
Zebralights all use an electronic switch, and therefore require a small stand-by current when fully connected. The standby drain on SC52 is low enough on standard cells as to be completely negligible (i.e., would take over a decade to drain an Eneloop). However, on 14500, the drain is bit higher – enough to fully drain a cell in under one year. Note that you can always physically lock out the light at the tailcap.
My SC52 sample had flickering issues at the "500 lumen" Max mode on 1x14500, with freshly-charged cells. As explained earlier in the review, this flickering disappeared <4.1V, and was highly dependent on the cooling state for Li-ion cells between ~4.1V and ~4.2V. I suspect there is some sample variability here, as only some users have reported similar issues near the 14500 max capacity level. Zebralight is aware of the problem, and working on a resolution - I will update this thread when I hear more.
The SC51 was known to have accidental activation issues (i.e., when I carried it as an EDC, I found that the SC51 could turn on if something pressed against the switch in my holster/pocket). I have been carrying the SC52 for better part of a week now, and have had absolutely no accidental activations yet. It thus seems like the revised switch design of the SC52 (i.e., smaller button, more recessed, firmer press need to activate) is effective at ameliorating this previous issue.
Preliminary Observations
The SC52 is a very impressive update to the SC5x-series of 1xAA lights.
I was impressed with the XP-G-based SC51 when it was first launched – especially with its class-leading max output and its extremely efficient runtime performance and good regulation pattern. It did have a few limitations though – no 14500 support, a rather smooth finish, PWM on lower modes (at least originally), and an annoying tendency toward accidental activation when carried as an EDC (typically on max!). I'm happy to report the SC52 has improved in all the above areas.
Let's start with the output – the XM-L-based SC52 is again a new class leader on standard AA cells. Regulation pattern is excellent (i.e., perfectly flat on all levels except max), and output/runtime efficiency has reached an even new high for the class, at all levels tested.oo: I don't know how Zebralight has managed to squeeze so much runtime out of their current-control circuit, at all levels now.
The support for 14500 is appreciated, although there are a few quirks here. My sample showed a flickering issue initially on fully-charged 14500 during the ultra-Hi max output stage. This flickering was both voltage and temperature dependent, and was easily resolved by draining off a small amount of capacity from the freshly-charged cell first. Regulation on 14500 was excellent, with perfectly flat output at all levels (something a lot of other multi-power lights can't match). Overall efficiency was very good, in keeping with other good current-controlled lights (but just very good - not at the outstanding efficiency levels seen on standard AA batteries).
I'm also glad to see that Zebralight appears to be quite accurate in their specs – including ANSI FL-1 output and runtime measures, according to my testing (see post #2 for an additional discussion of lumen estimation).
Build-wise, I like the new "ribbed" body design, which improves grip. I also personally like the larger head – in fact, I'd like an even longer body (I have fairly longer hands and fingers, so can find overly small lights problematic for handling). The more recessed switch (with firmer feel) is also greatly appreciated – no accidental activations so far, when carried on my belt. This is what caused me to give up on EDCing the SC51, so I'm glad to see they have addressed it here on the SC52.
So far, I'm not coming up with any negatives for the SC52, compared to its predecessor SC51. Beam pattern is bit more "floody" on the XM-L-based SC52 compared to the XP-G-equipped SC51, but peak throw remains pretty similar on max (thanks to the extra output).
It is frankly amazing to see a 1xAA light than can – on standard batteries – nearly match the output of many 2xAA or 1xCR123A lights. Coupled with its outstanding efficiency and excellent regulation patterns the SC52 is a real competitor for these other classes, not to metion its own 1xAA class. :wave:
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SC52 was supplied by Zebralight for review.
The SC52 is the latest refresh of the Zebralight line of 1xAA lights. I recall reviewing the very first Zebralight model ever produced – the 1xAA H50 (XR-E) – some five years ago now.
That was more of a headlamp model though, and was followed eventually by the traditional forward-facing SC50 (XP-E) and eventual SC51 (XP-G). The new SC52 is a XM-L-based model, with a revised build and greater output. Let's see how it compares to the earlier models, and the competition.
Manufacturer Reported Specifications:
(note: as always, these are simply what the manufacturer provides – scroll down to see my actual testing results).
- LED: Cree XM-L Cool White (Nominal CCT 6300K)
- User Selectable Levels: 3 main levels (High, Medium and Low). Each main level can be programmed to one of its two sub-levels. The second sub-level of the each main levels can be further programmed to different brightness levels or strobes.
- Light Output:
- High: H1 280 Lm (0.9 hrs) or H2 172 Lm (1.7 hrs) / 108 Lm (3 hrs) / 4Hz Strobe
- Medium: M1 50 Lm (7.5 hrs) or M2 25 Lm (12 hrs) / 12 Lm (27 hrs)
- Low: L1 2.7 Lm (4 days) or L2 0.34 Lm (3 weeks) / 0.06 Lm (2 months) / 0.01 Lm (3 months)
- Light output are ANSI out the front values. Runtime tests are done using Sanyo 2000mAh Eneloop AA batteries. Light output with 14500 batteries are the same except that the H1 is 500Lm for the first minute and then steps down to 280Lm.
- Operating Voltage Range: 0.7V - 4.2V
- Battery: One 1.5V AA (NiMH, lithium or alkaline) or 3.7V 14500 Li-ion battery. Batteries are not included in the package.
- Parasitic Drain: Negligible (equivalent to 16 years, much less than the self discharging of a battery)
- Automatic stepping down when battery (AA and 14500) capacity is low
- Built-in over-discharging protection for 14500 batteries (2.8V cutoff)
- Electronic soft-touch switch, with a 200,000 cycle operating life
- Smart user interface provides fast and easy access to all brightness levels
- Precision machined unibody casing from premium grade Alcoa aluminum bar stocks
- Proprietary heat sinking design bonds the LED board directly to the unibody aluminum casing
- Durable natural hard anodized finish (Type III Class I)
- Tempered optical grade glass
- Preinstalled bezel down pocket clip
- Orange peel textured reflector
- Anti-roll and tail-standing capable
- Battery power can be locked out by slightly unscrewing the tailcap to prevent unwanted activations or parasitic drain
- Beam Type: 80 degree spill, 12 degree hot spot
- Dimensions: Diameter: 0.93 inch (23.6 mm), Length: 3.08 inch (78.2 mm)
- Weight: 1.4 oz (40 gram)
- Waterproof to IPX7 (2 meters, 30 minutes)
- Accessories: two o-rings
- MSRP: ~$64
- This light has 3 main levels (High, Medium, and Low). Each main level can be programmed to one of its two sub-levels. The second sub-level of each main levels can be further programmed to different brightness levels or strobes.
- Basic Operation
- Short click turns on the light to High or turns off the light.
- Long click (press and hold for about 0.6 seconds) turns on the light to Low.
- Advanced Operation and Configuration
- Short click turns on the light to High. Short click again quickly to cycle from High to Medium, and Low.
- Press and hold to cycle from Low, Medium and High, release to set. When press and hold, the light always cycle from Low to High regardless which level you are currently in.
- Double click to toggle and select between the two sub-levels for that main level. Sub-level selections (except the strobe) for the 3 main levels are memorized after the light is turned off and through battery changes.
- The second sub-level of each main levels can be configured after 6 double clicks. Double click (startng with the 7th) to cycle and select different brightness levels or strobes. Short click to turn off the light when finishing configurations. The selections for the second sub-levels are memorized after the light is turned off and through battery changes.
- This light uses the main LED (flashing 1 to 4 times) to indicate the estimated remaining capacity of the battery. To start the battery indicator, (from Off) short-click 4 times without pause.
The SC52 came in the standard "eco-friendly" packaging that has been standard on Zebralight for some time now. Included in the simple (but firm) cardboard box was the light with removable clip (attached, with screws), two extra o-rings, a one-page instruction sheet, and a notice about battery use.
From left to right: Duracell AA NiMH; Zebralight SC52, SC51; Foursevens Mini AA, Quark AA; Sunwayman V11R+AA extender; Nitecore EA1, SENS AA, MT1A; Rofis JR-12.
All dimensions are given with no batteries installed:
Zebralight SC52: Weight 39.5g, Length 79.0mm, Width (bezel): 22.6mm, Width (max) 25.4mm
Zebralight SC51: Weight: 37.4g, Length 80.5mm, Width (bezel) 21.1mm, Width (max): 22.6mm
Nitecore MT1A: Weight: 54.6g, Length: 104.6mm, Width (bezel): 22.7mm
Nitecore SENS AA: Weight: 26.1g, Length: 82.7mm, Width (bezel): 19.8mm
Nitecore EZAA: Weight 20.9g, Length: 85.0mm, Width (bezel) 16.6mm
Rofis ER12: Wright: 35.5g, Length: 96.2mm, Width (bezel): 18.6mm
Tiablo E2A: Weight: 45.7g, Length: 101.2mm, Width (bezel): 19.9mm
Xeno E03:: Weight: 48.1g, Length 96.7mm, Width (bezel): 21.5mm
Xtar WK25B: Weight 42.9g, Length: 102.3mm, Width (bezel): 22.5mm
The SC52 is slightly shorter overall than the SC51 (which is impressive, given that it also has a deeper reflector and greater height clearance for longer 14500 cells, compared to the SC51).
The overall build design is similar to the earlier SC5x series lights. The most obvious changes are the slightly fatter head and the ridges along the body of the light. I definitely find the SC52 "grippier" than the predecessor SC51/SC50, which were a little too smooth in my view.
Anodizing remains the typical Zebralight "natural" finish (which is a bit more gray-green than most). Note that natural anodizing can be highly variable (e.g., my sample seems lighter colored than most Zebralights I've had).
Zebralight has finally started adding model labels to this series (previously, there were absolutely no identifying labels of any sort on SC50/SC51). The "Zebralight SC52" body label is applied to a a cut-out from the ridge detail, and is very legible.
As before, the SC52 still has a flat-bottomed tailcap (slight indentation now) and an electronic control switch in their head. The switch cover has a revised textured grip, and is more recessed than previously. It also has a firmer switch feel, requiring a more definite click to activate. Taken together, these features should help reduce accidental activations even further.
Tailcap threads are anodized as before, allowing for tailcap lockout. :thumbsup: This is important on all lights with electronic switches, since there is always some parasitic stand-by current drain to allow the switch to function (scroll down for a discussion in this case). Threads seem of comparable size and thickness to the earlier SC51.
The light can both tailstand and headstand.
The light comes with a removable metal pocket clip, held in place by two regular Phillips head screws.
As before, the light has a flat stainless steel bezel ring - but the head is wider now, with a wider and deeper reflector on the SC5. Reflector also seems to be less heavily textured than before (at least on my sample, which I would consider a light orange peel – LOP). The cool white XM-L emitter was well centered on my sample.
User Interface
The Zebralight SC-lights have always had a fairly unique user interface. While it may sound a little complex when first described, it is actually quite easy to use. The SC52's interface has been tweaked and expanded slightly from the SC51, but will feel familiar to those used to Zebralight.
On/off and mode switching is controlled by the electronic clicky switch.
Basic Operation
From Off, a quick-click (rapid press-release) of the switch turns the light on in Hi. If you repeatedly quick-click without much of a pause, the light will advance to Med, then Lo with another quick-click.
A slightly-sustained press-hold-release (hold greater than 0.6 secs) turns the light on in Lo. If you hold the switch longer, the light will advance through Med and then Hi, in a repeated Lo > Med > Hi sequence, until you let go of the switch to select the level you want.
At any time when On, press-and-hold to start the Lo > Med > Hi ramp.
A quick-click turns the light off.
Advanced operation
In regular usage, there are 6 possible output modes that are easily accessible, arranged in two sets of Lo/Med/Hi levels – the primary Lo/Med/Hi, and a sub-level set. Note that you can program the second sub-set (as explained in the section below).
To switch to one of the secondary Lo/Med/Hi sub-levels when on, double-quick-click the switch in any given level (e.g., in primary Med, double-click to go to the sub-level Med). The light will remember the selection of which Lo/Med/Hi level was last used, and return to that level the next time it is access (from Off, or as part of the ramp).
For convenience sake, Zebralight refers to the primary levels as L1, M1, and H1, and the secondary sub-levels as L2, M2, H2.
Programming the sub-levels
For the secondary sub-levels, you can actually choose from multiple choices. The primary levels are fixed.
For L2, you have the choice of three different levels. For M2, you have the choice of two different levels. For H2, you have the choice of two different levels or strobe mode (note that the strobe option can't be memorized as part of the standard operation). For the sake of clarity in my tables and graphs, I have referred to the programmable constant-output modes as L2A/L2B/L2C, M2A/M2B, and H2A/H2B. End result is that you actually have 10 defined constant outputs available to you, plus one strobe mode.
To program your desired secondary sub-level, double-click 6 times in any given level. Subsequent double-clicks will now alternate you between your various choices for that sub-level (e.g. M2A > M2B, in repeating sequence). To select the desired secondary sub-level, turn the light off by a single quick-click. When you next access that level, it will be saved to your programmed choice.
I realize the programming above may seem complicated, but you can safely ignore it all and simply use the light in basic mode as a 3-stage light. Or for that matter, as a 6-stage light in two sets of 3.
Video Overview:
For information on the light, including the build and user interface, please see my new 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.
PWM
There is no sign of PWM that I can see, at any output level – the SC52 is fully current-controlled, as claimed.
Note that the early SC51 had PWM on some of the lower levels (although I believe this was eventually replaced with current-control on that model as well). I am glad to see the SC52 is fully current-controlled right out of the gate.
Some users have reported seeing a brief flicker or pulse on the lowest possible output level (i.e. L2C, in my terminology). But I have not noticed one on mine – it seems perfectly stable, on all batteries.
Strobe:
The "hidden" strobe is a relatively slow 4 Hz (i.e., more of a signalling strobe than a tactical one).
Standby Drain
A standby current drain is inevitable on the SC52, due to the electronic switch in the head. Here is how the new SC52 compares to the earlier SC50 and SC51:
SC52: 129.1 uA on 14500, 20.2 uA on Eneloop NiMH
SC51: 41.8 uA on 14500, 14.2 uA on Eneloop NiMH
SC50: 7.4 uA on 14500, 2.3 uA on Eneloop NiMH
While there has been an upward trend in standby currents over time on the SC5x series, these values for the SC52 are still quite low in absolute terms. Assuming a standard 900mAh protected 14500, and a 2000mAh Eneloop NiMH, these currents would translate into 9.5 months on 14500, and 11.3 years on Eneloop.
Certainly, the drain is absolutely nothing to worry about on NiMH. The drain is higher 1x14500 (but still not unreasonable). But as always, I recommend you lock-out the light when not in use.
Flicker Issue on 14500
Some users have also reported flickering issues on Max on 14500, but this effect can be inconsistent. Note that the only difference in output between 14500 and NiMH/alkaline is the max mode (H1) runs at a higher level on 1x14500 initially (i.e., 500 lumens). After 1 min, the light steps down to typical max mode level for standard batteries (i.e., 280 lumens). The flickering, when observed in my case, has been on this first minute of 500 lumen output only.
There has been some speculation here as to whether this is due to different 14500 chemistries, voltage or heat. I can confirm that on my one sample, it is fact dependent on BOTH battery voltage and heat.
To explain, let me show you an oscilloscope trace for the first 65 seconds of runtime - on a fully charged AW protected ICR 14500 (~4.19V right off the charger), in my standard runtime testbed with a cooling fan.
Ok, not much to see here – the first spike shows the light On signal at time=1 sec, and the second spike is the step-down to the standard H1 level at t=60 secs.
Not let's try it again without any cooling applied:
Starting ~6 seconds after activation, the light begins flickering – at a rapidly accelerating rate. This rapid flickering continued until the light stepped down at 60 secs – at which point it ceased immediately.
How about a slower spinning fan?
Ok, now you see the flickering doesn't start until much later (~20 secs in), and is much more infrequent (i.e., slowly accelerating). I increased the fan speed to my typical level after ~35 secs, and you can see the flickering stopped immediately.
On the basis of the above, you could reasonably conclude that the flickering is mediated solely by relative heat (i.e., with sufficient cooling, you can prevent it from occurring).
But here's where it gets interesting – if I re-run the test with a partially depleted cell (~4.09V according to my DMM), with no cooling applied, I get this:
:thinking: Ok, now all you see are a few flicker spikes starting at the very end the first 60 secs 500 lumen level (which again ceased immediately with step-down). Note again, there is NO cooling applied to run above.
Note also that the actual output above is no different from the earlier runs (i.e., the 4.09V battery is giving the same ~500 lumens as the 4.19V battery did). So this tells you that the effect cannot be due solely to heat (i.e., the heat in the situation above should have been the same as the earlier no cooling trace, given that the outputs were the same).
It therefore seems that there is some sort of circuit issue whereby the light responds to high heat only if the 14500 is near max capacity. On my sample at least, these two variables are intertwined – you can't say the light never flickers <4.1V (it can – but only mildly without cooling), and you can't say it always flickers >4.1V (depends on the level of cooling).
I'm not quite sure what to make of all this, and have queried it with Zebralight. They have responded to me that they are aware of the issue, and are working to resolve it. When I hear more, I will update this thread. In the meantime, if you are finding a similar issue on your SC52, I recommend you either drain some capacity off your freshly-charged 14500 cells, or contact your dealer about a replacement. :shrug:
Beamshots:
All lights are on Max output on Sanyo Eneloop AA NiMH. Lights are about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance on the camera, to minimize tint differences.
1x14500 (AW Protected 14500) Li-ion Comparison:
Beam pattern is as you would expect for a XM-L light with this size reflector – a fairly big hotspot and decent sized spillbeam. Scroll down for full output details in my tables.
Testing Method:
All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. 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 ANSI/NEMA FL-1 Standard page for an explanation 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).
As you can see above, the SC52 has class-leading output – for both standard AA and 14500 Li-ion. The max output on 1xAA is particularly impressive.
oo: Throw is reasonable, given the size of the reflector.Since I don't have a lot of comparator data on other 1xAA XM-L lights, here are some summary tables for recent 2xAA and 1xCR123A/1xRCR lights I've recently tested (mainly XM-L-based). You can directly compare the output and throw values for the SC52 in the tables above to the tables below.
The SC52's ~290 estimated ANSI FL-1 lumens on max puts it a bit under most of the max outputs of the newer XP-G and XM-L 2xAA lights I've tested. That's to be expected, given that it is easier to have a sustained power draw from 2x AA cells in series than it is a single AA (i.e., you can't drive a 1xAA light as hard).
A similar pattern can be observed for most the 1xCR123A lights – typically, these have fairly similar max outputs to 2xAA lights.
On 1xRCR, the better comparable would be the ~540 estimated ANSI FL-1 lumens I get on the SC52 on 14500 Li-ion. That puts the SC52 in much the same category as many of the recent 1xRCR lights I've tested. This is as you would expect, as there is effectively no real difference between RCR and 14500, except perhaps greater runtime/capacity on some 14500s.
Lumen Estimate Summary
As with a number of my recent reviews, here is a summary table showing what my ANSI FL-1 lumen estimates are for the SC52:
Zebralight's reported ANSI FL-1 lumen specs seem pretty consistent with my output estimates (although my estimates seem to be a bit higher at the high end, and a bit lower at the low end). Part of this may simply be variability from one light sample to the next (e.g., it is hard for manufacturers to reliably reproduce the same sub-lumen levels in every light).
I know there's been some discussion here as to the accuracy of various lumen estimates. To expand on this in the case of the SC52, I have done some additional detailed comparisons to a Fenix light in post #2. :wave:
Output/Runtime Comparison:
Let's start with standard AA cells (NiMH Eneloop, alkaline, and Energizer L91 lithium):
Ok, there's a lot of data up there. :sweat:
The general take-home message is that the SC52 is a real output AND efficiency leader on standard cells.
oo: A second point is that the SC52 is typically quite well regulated (i.e. flat-regulated) on standard cells, except on max output (especially on alkaline, as expected). It is particularly impressive to see how long the SC52 runs on the Med-Hi levels, compared to equivalent output levels on other models. To help you compare to the Zebralight specs, here is a table comparing runtimes to the ANSI FL-1 standard of time to 10%:
Like with the Zebralight lumen output specs, the ANSI FL-1 runtimes seem fairly consistent with my testing as well.
As always though, I recommend you actually look at the full runtime graphs for more info on output level changes over time. Given the range of possible regulation patterns, it is important not to get fooled by looking at just two (rather arbitrary) points from the ANSI FL-1 standard – the full graphs tell you infinitely more (as I explain on my Testing Methods page).
1x14500:
On 14500 Li-ion, overall output/runtime efficiency of the SC52 is good, and seems pretty much in keeping with other lights in this class. However, the SC52 again shows very flat-regulation – which not all of the other lights were able to maintain.
As shown in my output summary table in the preceding section, Zebralight has also done an excellent job keeping output levels consistent between standard cells and Li-ions. The only real difference is on max (H1), where the SC52 shows a higher initial output for 1 min, before stepping down to the standard cell H1 level.
Normally that would be the end of my runtime comparisons, but I have been asked to show how the SC52 compares to other classes of lights. I provided summary tables for 2xAA, 1xCR123A and 1xRCR in the preceding section, and thought I would include 2xAA below (given the comparable battery chemistry).
2xAA Lights:
(NOTE that the SC52 is a 1xAA light, and all the others below are 2xAA!)
A couple of points strike me in this comparison of the 1xAA SC52 to the 2xAA lights. The first is that max output of the SC52 is not that much lower than the 2xAA lights – but standard cells get exhausted quickly at this level. You can really see this on the alkaline graph – there is simply no way that a 1xAA light is going to be anywhere near competitive to a 2xAA light on max drive levels on alkaline.
The second point is that the very high efficiency of the SC52 on its Med levels gives it the opportunity to compete fairly well with a lot of the 2xAA lights. No, it doesn't run quite as long for comparable output, but it is surprisingly close for a 1xAA light. Again though, you are best to run the light on NiMH or L91 lithiums to see the best performance here.
UPDATE FEBRUARY 1, 2013: Upon request, I've also plotted the max output of the SC52 against common XM-L-based 1xCR123A lights in my collection:
Please note that I have plotted *BOTH* L91 lithium and NiMH Eneloop for the SC52 above. In my testing, many 1xAA lights show slightly lower max output on L91 than they do on alkaline or NiMH. I'm not sure why (maybe to do with voltage?), but it is a common observation I've noticed over the years. :shrug: In the case of the SC52, I estimate ~290 ANSI FL-1 lumens on NiMH, and ~255 estimated lumens on L91.
I suggest you compare the full curves for how the lights perform, but in general terms, the SC52 is toward the middle of the 1xCR123A pack for initial activation output levels on max. Of course, regulation on lithium-based CR123A cells is typically flatter than NIMH.
Potential Issues
Zebralights all use an electronic switch, and therefore require a small stand-by current when fully connected. The standby drain on SC52 is low enough on standard cells as to be completely negligible (i.e., would take over a decade to drain an Eneloop). However, on 14500, the drain is bit higher – enough to fully drain a cell in under one year. Note that you can always physically lock out the light at the tailcap.
My SC52 sample had flickering issues at the "500 lumen" Max mode on 1x14500, with freshly-charged cells. As explained earlier in the review, this flickering disappeared <4.1V, and was highly dependent on the cooling state for Li-ion cells between ~4.1V and ~4.2V. I suspect there is some sample variability here, as only some users have reported similar issues near the 14500 max capacity level. Zebralight is aware of the problem, and working on a resolution - I will update this thread when I hear more.
The SC51 was known to have accidental activation issues (i.e., when I carried it as an EDC, I found that the SC51 could turn on if something pressed against the switch in my holster/pocket). I have been carrying the SC52 for better part of a week now, and have had absolutely no accidental activations yet. It thus seems like the revised switch design of the SC52 (i.e., smaller button, more recessed, firmer press need to activate) is effective at ameliorating this previous issue.
Preliminary Observations
The SC52 is a very impressive update to the SC5x-series of 1xAA lights.
I was impressed with the XP-G-based SC51 when it was first launched – especially with its class-leading max output and its extremely efficient runtime performance and good regulation pattern. It did have a few limitations though – no 14500 support, a rather smooth finish, PWM on lower modes (at least originally), and an annoying tendency toward accidental activation when carried as an EDC (typically on max!). I'm happy to report the SC52 has improved in all the above areas.
Let's start with the output – the XM-L-based SC52 is again a new class leader on standard AA cells. Regulation pattern is excellent (i.e., perfectly flat on all levels except max), and output/runtime efficiency has reached an even new high for the class, at all levels tested.
oo: I don't know how Zebralight has managed to squeeze so much runtime out of their current-control circuit, at all levels now. The support for 14500 is appreciated, although there are a few quirks here. My sample showed a flickering issue initially on fully-charged 14500 during the ultra-Hi max output stage. This flickering was both voltage and temperature dependent, and was easily resolved by draining off a small amount of capacity from the freshly-charged cell first. Regulation on 14500 was excellent, with perfectly flat output at all levels (something a lot of other multi-power lights can't match). Overall efficiency was very good, in keeping with other good current-controlled lights (but just very good - not at the outstanding efficiency levels seen on standard AA batteries).
I'm also glad to see that Zebralight appears to be quite accurate in their specs – including ANSI FL-1 output and runtime measures, according to my testing (see post #2 for an additional discussion of lumen estimation).
Build-wise, I like the new "ribbed" body design, which improves grip. I also personally like the larger head – in fact, I'd like an even longer body (I have fairly longer hands and fingers, so can find overly small lights problematic for handling). The more recessed switch (with firmer feel) is also greatly appreciated – no accidental activations so far, when carried on my belt. This is what caused me to give up on EDCing the SC51, so I'm glad to see they have addressed it here on the SC52.
So far, I'm not coming up with any negatives for the SC52, compared to its predecessor SC51. Beam pattern is bit more "floody" on the XM-L-based SC52 compared to the XP-G-equipped SC51, but peak throw remains pretty similar on max (thanks to the extra output).
It is frankly amazing to see a 1xAA light than can – on standard batteries – nearly match the output of many 2xAA or 1xCR123A lights. Coupled with its outstanding efficiency and excellent regulation patterns the SC52 is a real competitor for these other classes, not to metion its own 1xAA class. :wave:
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SC52 was supplied by Zebralight for review.
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