# Sunwayman V20C Variable (XM-L, 1x18650/2xCR123A) Review: RUNTIMES, BEAMSHOTS, VIDEO +



## selfbuilt (Sep 26, 2011)

*Warning: pic heavy, as usual. *











The V20C is the latest 1x18650, 2xCR123A light from Sunwayman – and one that features a continuously-variable magnetic control ring. Let's see how it compares to the competition … 

*Manufacturer's Specifications:*

LED: Cree XM-L LED
Digital Sensor Magnetic Control system - slightly twist the Rotator Ring from left to right to select desired mode from super-low current standby, output ranging from 0.5 to 438 lumens, to strobe function
Max Output: 438 Lumens (2hrs)
Min Output: 0.5 Lumen (120hrs)
Strobe: 438 Lumens
Constant current circuit, constant output
Effective range of 300 meters
Uses two 3V CR123A batteries or one single 18650 battery
Working voltage: 4~8.4V
High quality reflector maintains great throw distance and spread with an ideal beam pattern
Dimensions: 134mm (length) x 32mm (head diameter) x 25.5mm (tail diameter)
Weight: 120g (battery excluded)
Aerospace-grade aluminum alloy
Military Specification Type III- hard anodized body
Waterproof, in accordance with IPX-8 standard
Ultra-clear tempered glass lens resists scratches and impacts
Tactical forward click switch with momentary on
Tail stand capable- can be used as a candle
Included Accessories: Metal tactical ring, lanyard, holster, O-ring, rubber cap 
Includes Bonus AAA Keylight! 
Specifications of R01A:
Output: 10 lumens
Battery: 1 x AAA
Anti-roll design
Waterproof to IPX-8 Standard
Type III hard anodized body
Working Voltage: 0.9-4.2V
Dimensions: 70mm (length) x 14mm (diameter)
Weight: 13 g (battery excluded)
Included Accessories: o-ring, key ring 
MSRP: ~$95






Light comes with a good number of extras. Inside the packaging you will find the light, belt holster with closing flap, wrist lanyard, spare o-rings, tailcap button cover, and manual. Special bonus included with the light is a 1xAAA keychain light, with extra o-ring, small split-ring, and manual.

















From left to right: AW Protected 18650; Sunwayman V20C, T20C, M20C; Klarus XT-10; Olight M20; Lumintop P16X

All dimensions are given with no batteries installed:

*Sunwayman V20C:* Weight: 117.4g, Length 133.0mm, Width (bezel) 32.2mm
*JetBeam RRT-21:* Weight: 137.3g, Length143.3 mm, Width (bezel) 33.8mm
*Sunwayman T20C:* Weight: 118.3g, Length 136.8mm, Width (bezel) 32.0mm
*Nitecore IFE2:* Weight: 65.1g, Length 127.1mm, Width (bezel) 23.6mm
*Lumintop P16X*: Weight 141.4g, Length 157.0mm, Width (bezel) 37.9mm 
*Klarus XT10*: Weight 121.3g, Length: 144.8, Width (bezel) 34.9mm

The overall weight and dimensions of the V20C is about typical for this class, perhaps a bit on the small side compared to some lights. 






































Both the 1xAAA R01A keychain light and main V20C light are high quality. As always, anodizing is superb on my Sunwayman samples – a rich dark gray. Labels are clear and bright white.

Overall build is similar to a number of earlier Sunwaman lights, except for the added presence of knurling on the tailcap and control ring of the V20C. Knurling is of reasonable aggressiveness. With the removable grip ring installed, I would say overall grip is good. There is generous knurling on the R01A.

Screw threads are square-cut and anodized on both lights, allowing for lock-out. :thumbsup: I'm impressed that they managed square threads on the R01A – I don't think I've seen that before on a 1xAAA light. oo:

There is a spring on the positive contact plate in the head of the V20C, so higher capacity flat-top cells can be used.

The V20C can tailstand.

There are clear detents and labels on the magnetic control ring for Off, Max, and Strobe. 

Which brings me to a more detailed examination of the build and user interface, starting with a video overview: :wave:



Video was recorded in 480p, but YouTube defaults to 360p. Once the video is running, you can click on the 360p icon in the lower right-hand corner, and select the higher 480p option, or even run full-screen. 

*User Interface*

The R01A has a standard interface – tighten for On, loosen for Off.

The V20C has a forward tailcap clicky - press and release for momentary on, click for locked on. 

Mode switching is controlled by the magnetic control ring in the head. The V20C features a continuously-variable interface – you control the output level by twisting the ring. You can select your desired mode while the light is off. 

The ring traverses a little over 1/4 of the circumference of the light. When holding the light in front of you, turning the ring clockwise (i.e. to the right) increases the output level. There is a clear and firm detent just below the minimum output, which is a standby "Off" mode. There is another clear detent at the Max mode. A little further past Max is another detent for the Strobe mode. 

The arrowhead on the control ring helps you line up the mode you are in, and the control ring has good grip thanks to the knurling.

*Ramping Pattern*

The V20C uses what is basically known as a "visually-linear" ramp. Generally, here on the forums, that has been taken to mean a logarithmic ramp as opposed to an actual circuit-linear ramp of outputs. The reason for this is that we perceive brightness in a non-linear way (actually, not just brightness - most of our sensory perceptions are non-linear). This is part of why twice the lumens doesn't appear twice as bright to us - lumens are an objective (linear) measure of output, and our subjective perceptions are not linear. A logarithmic adjustment has long been used to try to compensate for our relative visual perceptions (e.g. the stops of camera are logarithmic). 

However a logarithmic adjustment is not entirely accurate – it is just a rough approximation of how our eyes and brain adapt to varying output levels (and one based on Victorian-era science at that). More extensive scientific research over the last several decades has revealed distinct power relationships that better correlate to our various relative sensory perceptions. For perceived brightness, the currently accepted linearization method is actually a cube root of output. For a full discussion of this - including detailed graphs and primary literature references - please see post #3 in my Sunwayman V10A review.

To put that in practical context, here is what the V20C looks like in my lightbox, compared to two other lights of the same class that also use ramping control rings. 














The V20C has a similar pattern to the Nitecore IFE2, which differs from the JetBeam RRT-21/15. Looking at the above graphs, it may appear to you that there is something wrong with the V20C and IFE2 – nothing happens over the early portion of the ring. In fact, the light is adjusting the output – it is just that it does so in a non-linear fashion, starting at really low levels and slowly ramping up. 

A much better way to depict how we perceive this change is to plot the lightbox output on a cube-root scale, the Stevens’ power law relationship:














This is what you can expect to see when you handle the lights. The V20C is very similar to the IFE2, in that you will spend a lot of time at the lower output levels upon initially turning the ring. This gives you very good dynamic control of the relative perceived brightness of the lights. Note also that like IFE2, the V20C goes to a much lower minimum output than most lights (see my Summary Tables later in this review for some lumen estimates). 

As many of you will have noticed, the V20C and IFE2 don't look entirely "visual-linear" on the graphs above (or in real life ). Again, I suspect the reason for this is that the ramp is actually logarithmic in circuit design, whereas we actually perceive relative brightness at something closer to a cube-root power relationship. Still, logarithmic is better than a regular circuit-linear ramp, which really doesn't match our relative perceptions at all. In the case of the RRT-21/15 above, you can see that you will spend most of the range of the dial choosing between near-maximal outputs. 

Personally, I prefer the nearly "visual-linear" logarithmic ramp of the V20C and IFE2, as they provide a better subjective experience – plus greater control over a wider dynamic range (thanks to the lower Lo modes). You just have to recognize that logarithmic doesn't fully correspond to how we perceive light, especially at the really low levels.

*Current Draw*

I have measured the battery current draw at the standby "Off" detent, and get 69uA on 1x18650, and 71uA on 2xCR123A. For a standard capacity 2400mAh 18650, that would translate into 4.0 years before a fully-charged cell would be drained. For 1500mAh CR123A, that would give you 2.4 years. 

Either way, nothing to worry about – these are remarkably low standby currents for a magnetic control ring. :thumbsup: And you can always fully lock-out the light by clicking the tailcap off, or unscrewing a quarter turn.

You would hope that this wide range of low modes and negligible standby drain would translate into a range of super-long runtimes. Unfortunately, the circuit overhead for this level of control is considerable, and Sunwayman estimates only 5 days runtime at the lowest level.

*PWM/Strobe*






The V20C's strobe mode is a tactical 11.2 Hz.

There is no sign of PWM that I can see, at any output level. Either they are using a frequency that is too high for me to detect, or the light is actually current-controlled as claimed. 

*Beamshots:*













The V20C uses a Cree XM-L emitter (well centered on my sample). Reflector is a light orange peel (textured reflector). Given that the reflector is fairly deep, I would expect throw to be pretty good for this size XM-L-based light.

And now the white-wall beamshots.  All lights are on max output, on 1x18650. 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. 





























































Beam profile of the V20C is remarkably similar to the JetBeam RRT-21. An overall balanced beam for a XM-L light.

*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 recently devised a method for converting my lightbox relative output values (ROV) to estimated Lumens. See my How to convert Selfbuilt's Lighbox values to Lumens thread for more info.

*Throw/Output Summary Chart:*

*Effective November 2010, I have revised my summary tables to match with the current ANSI FL-1 standard for flashlight testing. Please see http://www.sliderule.ca/FL1.htm for a description of the terms used in these tables.*











Sunwayman's ANSI FL-1 max output estimate seems very believable to me – but the beam distance (throw) seems rather over-stated. As expected from the beamshots, overall output and throw are very similar to the JetBeam RRT-21 – just a touch lower on the V20C. Again, a good balanced beam, but not a heavy thrower.

The V20C can do much lower Lo outputs than most lights – even lower than the rated 0.5 lumens in my testing. :thumbsup: I’ve put two sets of Min values in the tables above for the recent ramping lights; the first number is the minimum output when ramping down the light (before hitting Off), the second number in brackets is the lowest output when ramping up from Off. Many of these lights come on at a slightly higher output than they can ramp down to. 

*Output/Runtime Comparison:*



















V20C runtimes are excellent - about what you would typically expect to see for a good-quality, defined-level 2xCR123A/1x18650 XM-L-based light. Considering the V20C is continuously-variable (with a much greater range of outputs), that is very impressive. :thumbsup:

*Potential Issues*

Range of the magnetic control ring is only about 1/4 the total circumference of the light.

Light lacks a pocket clip.

*Preliminary Observations*

Sunwayman made a big splash with their first series of lights, and continues to impress as they refine and develop new models such as the V20C.

The implementation of the control ring is just about perfect, in my view. The approximately visually-linear ramp, the ultra-low Lo levels, the clear and firm detents (with strobe past the Max detent), the knurling on the ring to help with grip, and the ultra-low standby current – what is not to love? :kiss:

The relative issues are the number of labels (some may prefer a cleaner look, but they do help illustrate the modes) and overall traverse of the ring (I prefer it a little longer). Of course, many like it this short, as you can traverse the whole output range without having to change hand-grip.

The rest of the build is similarly high quality, and shows a nice evolution of the Sunwayman design. The excellent annodizing and square-cut threads are still present, and there is some knurling and a grip ring to help with grip now. The light is very comfortable to hold and use.  

Runtime performance is well in keeping with other XM-L-based lights that have a far more limited range of output levels. Consider the continuously-variable interface used here, the excellent efficiency at all levels is impressive. There were no surprises during the testing – the light worked consistently and unfailingly.

Oh, and the bonus R01A keychain light is a nice touch – a solid and sturdy single-mode 1xAAA light (a la Fenix E01, or early ARC AAA).

Frankly, I have little to criticize or recommend here – the V20C pretty much met all my expectations. Sure, there are other lights driven to higher max levels, or with bigger heads for more throw. But the V20C truly appears to be an outstanding general-purpose, well balanced, 1x18650/2xCR123A XM-L based light. :thumbsup:

----

V20C provided by Sunwayman and Battery Junction for review.


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## selfbuilt (Sep 26, 2011)

Given the recent release of the JetBeam RRT-21, I am sure a lot of users would like to know how it compares to the V20C.

I don't normally make direct commentary comparisons, but this is an unusual situation - these continuously-variable lights have almost identical beams, similar max output, and virtually identical output/runtime efficiencies at all levels. When you consider both builds are very high quality, how do you choose between them? :thinking:

The main difference is the V20C has a "visually-linear" ramp with a much greater number of low levels (absolute min output is much lower). It also has a much lower standby drain (although that shouldn't matter, as you should always store the light clicked off or locked out). The traverse of the control ring on the V20C is also a lot less than the RRT-21 (i.e. about half), and the RRT-21 lacks any labels on its ring. The V20C is also marginally smaller, so may be easier to pocket.

Personally, my ideal is probably somewhere in-between these differences (i.e. I like the ring traverse length of the RRT-21, but wished it had the visually-linear ramp and lower outputs of the V20C). I also personally like a minimum of labeling. 

At the end of the day, I don't think you would go wrong with either – performance and overall build is comparable, so it really comes down to the specifics of the control interface. I recommend you decide on your relative preference for the ring characteristics and overall build styling. :wave:


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## phantom23 (Sep 26, 2011)

Nitecore V20C?


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## selfbuilt (Sep 26, 2011)

phantom23 said:


> Nitecore V20C?


Thanks, fixed that.  It is now properly listed in the review tables (hit your browser re-load to see the new tables).


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## Multitaskertools (Sep 26, 2011)

that's a gorgeous looking light; Sunwayman build quality is really top-notch, and i really like the new control ring

might have to get one...


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## Multitaskertools (Sep 26, 2011)

PS - is the pocket clip the same as other Sunwayman lights? shame they're not like XENO's.


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## selfbuilt (Sep 26, 2011)

Multitaskertools said:


> PS - is the pocket clip the same as other Sunwayman lights? shame they're not like XENO's.


There was no clip included on my sample, the V20C doesn't seem to have one. Seems like an odd omission, as even the original Sunwayman clip was better than nothing. But I agree, a firm fitting clip would be good.


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## candle lamp (Sep 27, 2011)

Excellent review and thanks for your time & effort as always. Selfbuilt! :twothumbs
Also video is very helpful to learn UI and looks like user manual.
I like the visually-linear ramp with a greater number of low levels on the V20C and longer traverse of the control ring on RRT-21(I prefer about 120 degree). 
What I prefer is V20C.



selfbuilt; said:


> You would hope that this wide range of low modes and negligible standby drain would translate into a range of super-long runtimes. Unfortunately, the circuit overhead for this level of control is considerable, and Sunwayman estimates only 5 days runtime at the lowest level.


 
I'm not sure if 5 days runtime at the lowest level(maybe 0.02 or 0.2 lumens) is not enough long runtimes because I don't have any magnetic controled flashlight. 

Edit : According to the manufacturer's spec., the working voltage(4~8.4V) may make you to use two rcr123. What do you think of it?


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## selfbuilt (Sep 27, 2011)

candle lamp said:


> I'm not sure if 5 days runtime at the lowest level(maybe 0.02 or 0.2 lumens) is not enough long runtimes because I don't have any magnetic controled flashlight.


No, 5 days is quite reasonable in absolute terms. It is just that you can probably expect that long for both 0.02 and 0.2 lumens. Generally, as a light drops to lower levels, runtimes continue to increase (e.g. think of the HDS lights). But it is very rare for a continuously-variable light to last longer than a week, no matter how low it goes. This is not a problem - I only mention it to manage expectations.



> According to the manufacturer's spec., the working voltage(4~8.4V) may make you to use two rcr123. What do you think of it?


Yes, it may work - but 8.4V max is cutting it rather close (i.e. freshly-charged RCRs will exceed that slightly). Since there is no information showing direct support for RCR, I decided to err on the side of caution and stick with what is officially supported.


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## candle lamp (Nov 21, 2011)

Thanks for your reply. Selfbuilt!

Does V20C have reverse polarity protection function?


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## selfbuilt (Nov 21, 2011)

candle lamp said:


> Does V20C have reverse polarity protection function?


Hmm, don't know. If it does, it would be entirely circuit-controlled (based on the spring in the head, alllowing use of flat-top cells). Would need to ask Sunwayman directly.


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## JML (Mar 2, 2012)

The Olight battery tube (for 2x CR123A batteries) fits in the V20C perfectly. Mine have had the little tab for carrying cut off and smoothed (to fit in other lights), so I don't know if the uncut tubes will fit. These make battery changes easier, and prevent any rattling of the batteries.


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## selfbuilt (Mar 2, 2012)

JML said:


> The Olight battery tube (for 2x CR123A batteries) fits in the V20C perfectly. Mine have had the little tab for carrying cut off and smoothed (to fit in other lights), so I don't know if the uncut tubes will fit. These make battery changes easier, and prevent any rattling of the batteries.


Thanks for the comments. The V20C is a very nice light. It doesn't seem to have garnered enough attention here, likely because it is a general purpose light. But it's great for all sorts of uses.


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## JML (Apr 16, 2012)

That pictured Olight tube I posted above is the OLD style. I just got some new ones, which are split tubes without a threaded cap. They work fine, without alteration. The similar EagleTac sleeves work in the V20C, too.

My second V20C has a different color than the first. The first was a very dark olive drab, like the reviewed sample; the second is much, much closer to black. On each light, every part matches perfectly. 

One point I think they got wrong: the grip ring. It shouldn't be aluminum HA-III, because threading the ring onto the body will pull off some flecks of HA-III from the light's body; it's inevitable. They should either replace the aluminum ring with a plastic or rubber one that won't abrade the body, or (better option) provide a thin aluminum ring, knurled to match the other sections of the body, that the user can thread on instead the grip ring.


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## awes (Feb 10, 2013)

Is there some kind of a low voltage indicator? I'd like to use it with unprotected 18650s.


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## selfbuilt (Feb 10, 2013)

awes said:


> Is there some kind of a low voltage indicator? I'd like to use it with unprotected 18650s.


Not as such - but in my protected cell tests, the light always dropped off in output before the built-in protection circuits got triggered (at all levels I tested). This means that you will be able to tell by the reduced output that your 18650 is almost fully depleted, and should be recharged. May not be as obvious at the really low levels, but you should definitely be able to tell by the fact that you can't get higher outputs any more.


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## Jon_tom (Jun 1, 2013)

Selfbuilt, 

In your video review, you mention that many new variable output designs are using continuously-visual ramping circuits. Could someone give me a list of lights that ramp in this way for 1x18650s besides the Nitecore IFE2 (which is discontinued?)? Thanks!


Jonathan


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## selfbuilt (Jun 2, 2013)

Jon_tom said:


> In your video review, you mention that many new variable output designs are using continuously-visual ramping circuits. Could someone give me a list of lights that ramp in this way for 1x18650s besides the Nitecore IFE2 (which is discontinued?)? Thanks!


There is not a lot in the 1x18650 class with "visually linear" control ring ramps, but Nitecore, Sunwayman and Jetbeam have all been known to use them on some models (although the Jetbeam RRT-15 an RRT-21 were not visually linear). The Crelant lights (press and hold ramps) are fairly visually linear.

I'm currently testing the Nitecore SRT7, and it has an interesting version of a "visually linear" ramp. I'll know more when I complete that review - working on the testing now.

Oh, and :welcome:


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## Jon_tom (Jun 10, 2013)

selfbuilt said:


> There is not a lot in the 1x18650 class with "visually linear" control ring ramps, but Nitecore, Sunwayman and Jetbeam have all been known to use them on some models (although the Jetbeam RRT-15 an RRT-21 were not visually linear). The Crelant lights (press and hold ramps) are fairly visually linear.
> 
> I'm currently testing the Nitecore SRT7, and it has an interesting version of a "visually linear" ramp. I'll know more when I complete that review - working on the testing now.
> 
> Oh, and :welcome:





Thanks so much for your reply! I'm looking forward to the whole SRT series so I'm excited to hear your working on a review. 

And thanks for the welcome.


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## NetNathan (Jun 23, 2013)

I just received my V20C. And I throughly enjoy it. 
It is not as bright as others but plenty bright enough. 
H main reason I got it was he variable adjustment ring. This should be a standard, all the diff button operations of most of the flashlights are a pain. 

I really liked Nitecore design and now I see the SRT7 is out with an adjustment ring, a ton of throw, and a nice kudo of the different color modes. Arghh.... 

You should do a review of the lights with variable adj rings....


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## selfbuilt (Jun 24, 2013)

NetNathan said:


> I really liked Nitecore design and now I see the SRT7 is out with an adjustment ring, a ton of throw, and a nice kudo of the different color modes. Arghh....
> You should do a review of the lights with variable adj rings....


:welcome:

I do what I can, but it depends on what manufacturers want to send me (and what I have time for). FYI, I do indeed have a review of the SRT7.

For all that, I think the V20C still hangs in quite well for the class. While not as high in max output, you won't really see that difference in practice anyway (due to the non-linear way we perceive light). Still a nice beam, for those who want a less-throwy option.


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