Warning: pic heavy, as usual.
Zebralight updated their popular 1x18650 model a little while back, now named the SC600 Mk II. More recently, they have updated the emitter to XM-L2 – which I now have on hand to review.
Let's see how the model has evolved from the original SC600 - and how it compares to other recent lights in the popular 1x18650 class of XM-L2 lights.
Manufacturer Reported Specifications:
(note: as always, these are simply what the manufacturer provides – scroll down to see my actual testing results).
- LED: Cree XM-L2 Cool White (Norminal 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.
- Light Output (runtimes)
- High: H1 1100 Lm (PID, approx 2 hr) or H2 670 Lm (PID, approx 2.5 hrs) / 356 Lm (3.9 hrs) / 162 Lm (11 hrs)
- Medium: M1 70 Lm (30 hrs) or M2 32 Lm (66 hrs) / 12 Lm (172 hrs)
- Low: L1 3.8 Lm (16 days) or L2 0.43 Lm (2.5 months) / 0.06 Lm (4.6 months) / 0.01 Lm (5.5 months)
- Beacon Strobe Mode: 0.2Hz Beacon at Low / 0.2Hz Beacon at H1 / 4Hz Strobe at H1 / 19Hz Strobe at H1
- Light output are ANSI out the front (OTF) values. Runtimes tested (and parasitic drain estimated) using ZL631 batteries. Runtimes of the two PID controlled levels (1100Lm and 670Lm) vary greatly with ambient temperature and air circulation.
- Operating Voltage Range: 2.7V - 4.2V
- Battery: One 18650 size (up to 69mm long) 3.6/3.7V li-ion rechargeable. Batteries are not included in the package.
- Parasitic Drain: Negligible (much less than the self discharging of a battery)
- Beam Type: 80 degree spill, 10 degree hot spot
- PID thermal regulated outputs (1100Lm and 670Lm)
- Battery capacity indicator (LED flashes 1-4 times, 4 short clicks to start)
- Automatic stepping down from High to Medium, and from Medium to Low when battery capacity is low
- Built-in over-discharging protection (2.7V cutoff)
- Durable electronic soft-touch switch
- Smart user interface provides fast and easy access to all brightness levels and beacon-strobes.
- Precision machined unibody casing from premium grade 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)
- Sealed and potted LED driver circuitry
- Tempered optical grade glass
- Orange peel textured reflector
- Battery reverse polarity protection
- Pocket clip
- Lanyard ring
- Waterproof to IPX7 (2 meters, 30 minutes)
- Dimensions: Head Diameter: 30 mm, Body Diameter: 25 mm, Length: 101.6 mm
- Weight: 2.75 oz (78 gram) without battery
- MSRP: ~$95
Inside the standard eco-friendly Zebralight cardboard box, you fill find the light with pocket clip, spare o-rings, and manual.
From left to right: AW Protected 18650 2200mAh; Zebralight SC600-II L2, SC600; Olight S20-L2; Nitecore EC2; Eagletac D25LC2; Eagletac TX25C2, Sunwayman C21C.
All dimensions directly measured, and given with no batteries installed:
Zebralight SC600 II: Weight 79.3g, Length: 101.8mm, Width (bezel) 29.7mm
Zebralight SC600: Weight 87.2g, Length: 107.8mm, Width (bezel) 29.7mm
Eagletac D25LC2: Weight: 50.0g, Length: 116.3mm, Width (bezel): 22.5mm
Eagletac TX25C2: Weight 93.6g, Length: 120.4mm, Width (bezel): 31.6mm
Foursevens Quark Q123-2 X (Regular tailcap): Weight: 44.6g, Length: 112.7mm, Width (bezel) 22.0mm
Olight S20 (2012, XM-L): Weight: 51.8g, Length: 105.4mm, Width (bezel): 23.1mm
Sunwayman C21C: Weight 78.6g, Length: 102.0mm, Width (bezel side) 26.9mm (bezel diagonal) 31.2mm
The new SC600-II is even more petite than the original – it is surprisingly quite compact for the 1x18650 class, despite the larger than typical reflector.
The build of the SC600 II remains distinctive, with its relatively large head (i.e., most other compact lights have slim heads as well). I understand from Zebralight that the body is now machined from a single bar of Alcoa aluminum, sourced in the U.S. (same goes for the emitters).
The natural-finish anodizing is somewhat darker than I've seen on most Zebralights (apparently also a result of switching to US manufacturing for both the aluminum and anodizing, according to ZL). Zebralight confirms it is still type III (hard anodized). The finish seemed excellent on my sample (I had previously noticed some fine lines on some of their earlier models with the old anodizing). As always, labels are very minimal and small, though clearly legible against the background.
As before, knurling is not very aggressive on the body, but does provide good grip on the tailcap. There are also finger wells and other body elements to help with grip, as before. Rolling is reduced due to the addition of the split-ring attachement point now, near the tail. Screw threads are anodized for tailcap lock-out.
As always with all Zebralights, the control switch is electronic and located on the head. Switch feel is slightly stiffer than most lights with this kind of switch, and the button is slightly recessed in the opening to limit the risk of accidental activation. Overall feel is similar to the earlier SC600 (i.e., you may need a firmer press than on some competing lights).
Light can tailstand as before, thanks to the flat base.
Pocket clip is similar to the later generation SC600, and feels more substantial than typical in this class. Note the clip is reversible (i.e. can attach near the head or the tail, pointing in opposite directions).
There is now a small spring on the positive terminal contact board in the head (replacing the previous raised button). Despite this, there actually seems to be slightly more room for extra long cells now, compared to the SC600 (i.e., Zebralight has condensed the head internals even more than it would appear from the external measurements). All my flat-top high capacity cells fit and worked in the light.
The main reflector is textured, to a medium-to-high orange peel finish. It appears to be slightly deeper than my SC600 sample. XM-L2 cool white emitter was well centered on my sample.
The AR coating seems slightly changed from my earlier SC600. According to Zebralight, this is due to sourcing the glass from a US manufacturer now.
Finally, I'm informed by Zebralight that there have been a few internal changes as well (that I can't directly verify). Apparently, the driver board is integrated with the emitter star board now - which would certainly help explain the lower overall height despite accommodation for extra length cells (and slightly deeper reflector). Most of the circuit components are apparently also sourced from US distributors now. Finally, the head circuitry is apparently potted now.
The SC600-II L2 uses the latest variant of the classic Zebralight interface. While it may sound a little complex when first described, it is actually quite easy to use.
On/off and mode switching is controlled by the electronic clicky switch. The main level choices are Lo – Med – Hi. There are two possible memorized outputs at each level, commonly referred to as 1 or 2 (e.g. Lo1/Lo2, Med1/Med2, Hi1/Hi2). And for each of the second levels, you can choose between 2 or 3 options. This gives you a total of 11 constant outputs to choose from. There are also 4 blinking modes.
I know that may sound confusing, but the interface is actually well layout for simple operation. Let me walk you through everything:
By default, the light is set to come on in Hi1, Med1 or Low1. You could therefore easily use the light as a simple, straight-forward three-mode light, if you want.
To get Hi initially, do a quick single click from Off. You can click quickly again to cycle from Hi to Med, and Low - but you need to perform these extra clicks reasonably rapidly, yet not as rapidly a double- or triple-click (i.e. from Off, a single-click is Hi, two single clicks is Med, and three single clicks is Lo). As with everything on a Zebralight, it takes a bit of use to get the timings right. After about a second or so of being On, a quick click will simply turn the light off.
Alternatively, from Off, a slightly longer press and hold (i.e. >0.5 sec) turns on the light in the Lo mode.
To advance from one mode to the next while the light is On, press and hold the switch to cycle through Lo > Med > Hi, repeatedly (you can do this directly from Off too). Release the switch to select the level. As before, a quick click turns off the light.
The sequence is actually surprising versatile - you can choose your preferred way of accessing the three main levels.
Secondary modes for each level
When On, a quick double-click at any time switches to/from the secondary mode for that level (i.e. 1 or 2). The light will memorize your choice and return to it next time you cycle or turn on at this level. The memory even lasts through battery changes.
As before, you also have a few choices as to what the secondary mode can be for each level (in fact, you have a few more choices now). To select this choice, let me use the the Hi level as an example. To enter the programming feature, double-click the light 6 times rapidly. Now, every additional double-click will advance you through the three programmable options (670 Lm, 356 Lm, 162 Lm). To select the mode you want as Hi2, simply turn off the light once you have made your choice. When you next turn it on, that last level will have been memorized as Hi2, and returned to automatically. There are now two possible Med2 levels, and three possible Lo2 levels to choose from.
Blinking modes are hidden away under a rapid triple-click of the switch from off. You can switch between four blinking options by double-clicking the switch once On in this state (a single click reverts you to the constant output modes). Mode sequence for the double-click is: Fast Strobe > Lo Beacon > Hi Beacon > Slow Strobe, in repeating sequence.
Another new feature on the SC600-II is a relative battery life remaining indicator. Quadrupule-click the switch from off, and the main emitter flashes out a relative battery strenth (flashes 1-4 times, with 4 being nearly fully charged).
And that’s it – it is really very simple in practice, once you get used to the timings.
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.
As with my other Zebralight lights, I don't see any signs of pulse width modulation (PWM) on any the lower output modes. The light appears to be fully current controlled at all levels.
I did detect a few oscilloscope spikes on occasion when first entering Hi1 output level, but these disappeared rapidly (i.e., I was not able to capture an oscilloscope trace of them).
The fast strobe mode is a disorienting ~18Hz tactical strobe.
The beacon modes have a common frequency of one quick flash every ~5 secs. The intensity is different between the two modes (i.e., one at max, one at a lower level)
The slow strobe has a frequency of ~4 Hz, which makes it a good general signaling strobe.
Due to the electronic switch, all Zebralights have a constant parasitic stand-by current drain when the tailcap is connected.
In the case of the SC600-II L2, I am happy to report the standby current is a negligible 4.3uA. Zebralight isn't kidding when they say this is below the self-discharge rate of a standard battery - for a 2600mAh cell, that would theoretically translate into 69 years before the battery would be drained.
Note this is an improvement over the original SC600, which I measured at 69.6uA. This was still reasonably low (i.e, over four years and three months to drain a 2600mAh cell), but it's nice to see the further improvement.
As before, you can fully break this current - and physically lock-out the light - by twisting the tailcap a quarter turn.
For white-wall beamshots below, all lights are on Max output on an AW protected 18650 battery. 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.
Overall beam pattern is very similar to the earlier SC600, as you would expect. Overall output has definitely increased however, and it does seem a touch more focused for throw. Beam pattern is also similar to my recently reviewed compact Sunwayman C21C.
Scroll down to see my summary output/throw table.
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).
As you could tell from the beamshots, max overall output has increased from the original SC600 (which was a class leader when it came out). The SC600-II is similarly the current highest output 1x18650 light I've tested. This is presumably due to the extra protection provided by the PID controller on the highest output levels (scroll down to my Runtimes for a discussion).
Significantly, the lowest output levels have dropped considerably as well. At the lowest level, you can now quite comfortably stare into the emitter (for hours on end, if you were so inclined).
Peak intensity throw/beam distance is as you would expect for this light (i.e., it is still not particularly throwy).
Let's see how it does on my estimated lumen scale:
Overall, my lumen estimates are pretty close to Zebralights specs. The lowest output modes seem lower than the specs would suggest, but that could be due in part to sample variation.
As always, note my lumen estimation method is just that – an estimation based on the calibration of my lightbox. As such, don't get caught up on the absolute difference between lights or levels, as I can't guarantee absolute accuracy. Focus instead on the relative differences, as that is internally consistent across all my reviews.
Let's start with a comparison of the Hi modes, under my standard testing conditions (i.e., a cooling fan is used)
All levels show a clear step-down pattern as the batteries near exhaustion. This is convenient, as it means you won't be stranded in the dark without warning.
But you can also see some evidence of the PID circuit feature on the max mode (Hi1). Although the overall pattern is similar to the drop-off seen on many lights as the batteries/circuit head up, there are actually a lot of very finely discriminated steps in output happening. This will not be apparent to you in practice (i.e., they are too subtle to see), but my lightbox can indeed detect the precise thermal regulation introduced by the PID.
You can read up more about PID (Proportional-Integral-Differential) controllers online, but basically they are a more sophisticated mechanism to regulate circuit function in regards to temperature than the typical step-down features we are used to with flashlights. The controller has to be specifically customized to the build in question, and can be thought of a refinement/replacement of the typical current-control regulation we are used to.
According to Zebralight, both the Hi1 and H2A levels use PID. This presumably explains why they are unable to provide typical runtime estimates (i.e., depends a lot on ambient temperature conditions). Note that I don't see any thermal step-down on the Hi2B runtime above - likely due to my use of cooling fan during testing.
To explore this in more detail, here is a close-up of the H1 and H2A modes with and without a cooling fan:
Now you can really see the PID in action. On the Hi1 mode, there's no difference in the runtime pattern due to cooling over the first 5 mins or so. Beyond that point though, the non-cooled runtime shows a progressive drop in output – down to below the Hi2A level. Of course, this also means the light can run for a lot longer, as you are not draining the cells as quickly.
A similar (though less pronounced) effect of the PID can also be seen on the Hi2A run. Output again remains initially consistent between cooling and non-cooling runs, but eventually becomes divergent. By ~25 mins into the non-cooled run, there is a definite drop off in output, although it is not as pronounced as the Hi1 (in relative terms).
That said, the sustained output level of both Hi1 and Hi2A is remarkably consistent once step-down occurs. At the 30 min mark, I would estimate the PID-reduced output on the non-cooled runs to be ~600 lumens on both levels. By 80 mins, it has consistently dropped to ~560 estimated lumens.
Once the pronounced step-downs occur (due to declining battery voltage), performance on the non-cooled runs looks the same as the cooled runs.
Here's a comparison of my standard AW 2200mAh cells to a NCR18650A cell (Xtar 3100mAh)
Finally, let's do a brief examination of surface temperature relative to output. This was done by simultaneously logging data from a temperature probe taped to the head (on the opposite side from the switch, near the base of the head). There is no cooling applied, and I am using the same Xtar 3100mAh cell as above:
As you can see, the PID keeps the temperature within a remarkably consistent range. Again, don't worry about the absolute temp value (that just reflects the specific probe placement).
Let's see how the fan-cooled SC600-II L2 compares to the competition (all on AW protected 2200mAh):
Zebralight's SC600-II L2 is showing top-of-class efficiency and regulation on 1x18650.
Note however that this light has a narrower circuit range than most of the competition (i.e., doesn't support 2xCR123A or 2xRCR) -this helps reduce overhead, and facilitates efficiency gains. But the degree of improvement (while maintaining full regulation) is still impressive.
Like its predecessor model, the new SC600-II is 1x18650 only (i.e., it doesn't take 2xCR123A or 2xRCR).
As with other heavily-driven lights, some 18650s may not be able to handle the sustained discharge rate on Max. I recommend you stick with high-quality cells.
Switch timing takes a little getting used, if you aren’t already familiar with Zebralight.
First the headline news: the new SC600-II L2 tops my charts for initial max output on a single 18650 (at least for now).
It really is a surprising amount of light from such a small package. It would seem the introduction of the PID thermal controller has allowed them to drive the light a bit harder than the competition. Of course, the PID will regulate output in response to temperature - and no light on a standard ICR chemistry 18650 cell is going to be able to keep that >1000 lumen output up for long. But the PID is an interesting and sophisticated way to minimize the disruption in output due to heat (i.e., much more finely tuned than previous thermal controls I've seen). Scroll back up to my Runtimes section for a discussion.
Output/runtime efficiency remains top-of-class for the SC600-II L2. On both the PID-controlled Hi1 and Hi2A levels, and the standard current-controlled lower levels, you see excellent efficiency across the board. I quite like the low battery voltage step-down feature (on all levels), as it means you will never get stuck with no light without warning. Regulation patterns are excellent, in my view. Keep in mind however than only 1x18650 is supported.
The overall build looks similar to the earlier light, but the Mk II version is quite a bit smaller than the SC600 (which was petite to start with). The revised star/circuit sandwich on the Mk II version has clearly saved them a lot of space in the head, as I find it is even easier to accommodate longer 18650 cells now.
The switch feel and user interface will seem very familiar to Zebralight owners - but as always, there are a few updates here. I like the extra options on the programmable second modes of each output level (i.e., more constant output choices now). I am also happy to see strobe/blinky modes moved out of the main sequence and hidden under the new triple-click feature. The lower Lo modes are also always appreciated (i.e., several true sub-lumen Moonlight modes now). And the battery indicator feature is a cute touch. As ever, this feels like a continued evolution of the user interface - and one that gets better on every iteration of the light.
Although the revised reflector design gives you marginally more throw, I would still consider the SC600-II to be more of a floody style of light.
As an aside, it is seems that Zebralight has switched to largely US-based distributors and manufacturing (if that is important to you).
At the end of the day, the new SC600 Mk II L2 is a measurable improvement over the original SC600 in every sense (and that was a pretty nifty light in its own right). No doubt about it, this light is a strong contender in the 1x18650 space. Hopefully you will find the detailed comparisons above useful in coming to your own conclusions.
SC600-II L2 provided by Zebralight for review.