[selfbuilt]

SmartFire V-68C "Q5" MRV-clone - UPDATED



This is a quick review of the new “MRV-clone” light, the 18650-only Smartfire V-68C Q5. The body design appears to be a knock-off of the MRV, but with some important differences. I got mine from Kai Domain, but I know DX also sells it.

For a detailed comparison to all the other thrower lights in my collection, please see:
Thrower review: DBS, Spear, MRV, Tiablo, Regal & clones: THROW, RUNTIMES, BEAMSHOTS!

UPDATE 2/7/08: After isolating the contacts around the emitter pill, the "flickering" issue in my low mode and strobe modes has been resolved. This is the minimum required fix for all users of this light - failure to do so could result in shorting out the emitter fairly quickly (including upon initial activation!). Buyer beware ...

The contenders:

On the left, the Smartfire V-68C, on the right, Lumapower MRV (2nd Gen),



Weight:
Lumapower MRV: 195g
Smartfire V-68C: 137g

As you can see from the non-battery weights, the light is not going to be as substantial as a MRV.

I’ve saved beamshots for the end, after the discussion of build quality.

Measurement Method:Throw values are the square-root of Lux measurements taken at 1m using a light meter. Note that my lightmeter tends to report lower absolute values than most, but I have verified it is linearly responsive over the range of intensities in question.

Smartfire V-68C “Q5” (18650-only) Throw Lux @ one meter:

• 18650 x 1 on high with stock lens: 15,000 Lux
• 18650 x 1 on high with MRV lens: 16,300 Lux
• 18650 x 1 on high with UCL-AR lens: 17,000 Lux
• 18650 x 1 on low: 6,000 Lux

MRV 1st Generation with DX Cree Q5 WG mod - Q5 Throw Lux @ one meter:

• 18650 x 1 on high: 11,800 Lux
• 18650 x 1 on low: 8,500 Lux
• CR123A x 2 on high: 18,200 Lux
• CR123A x 2 on low: 8,500 Lux

Dereelight DBS 3-Stage - Q4 (18650-only) Throw Lux @ one meter:

• 18650 x 1 on high: 21,200 Lux
• 18650 x 1 on medium: 10,500 Lux
• 18650 x 1 on low: 1,830 Lux

DX WF-600 (18650-only) - Q2 Throw Lux @ one meter:

• 18650 x 1 on high: 16,300 Lux
• 18650 x 1 on low: 3,600 Lux

Throw observation:

• At first glance, the V-68C throws the same as the Q2 WF-600 on 18650 on Hi - despite the Q5 label on the V-68C. However, I believe this light does indeed contain a Q4 or Q5 emitter (scroll down to build quality for a discussion).
• Throw improves with a better quality lens (see my discussion in post #36 here).

Runtimes:
Runtimes charts are slightly different from my other reviews - since my home-made milk carton lightbox doesn't accurately capture overall output on these intense throwers, I have adjusted all my relative output numbers to initial throw (measured as the squareroot of Lux @1m). This allows you to directly compare the relative throw of each light over time on the graphs below (although you can't directly compare these graphs with my other reviews).



Runtime observation:

• Again, the V-68C performs exactly the same as the Q2 WF-600 on 18650 on Hi. And again, see below for a potential explanation why.

Build Quality:

Let’s start at the top, the source of the throw problem: the V-68C (left) lacks an o-ring around the lens in the bezel.

EDIT: You can solve this problem with a 40mm x 1.5mm o-ring available from oringsusa.com. Once you add the o-ring, waterproofness should be halfway decent.



The light seems to use a similar-size reflector as the MRV, and the head/bezel has the exact same dimensions. But since the o-ring is missing, the reflector “wobbles” loosely inside the head unless you have it screwed all the way tight against the body so that the actual emitter seems to be holding the reflector firmly in place. This is obviously a huge potential problem, since if the aluminum reflector touches the Cree contacts you could short the emitter.

Are the contacts protected? Let’s take a look under the hood.



Note that I have not removed anything – this is exactly what you see when you unscrew the head (i.e. unlike the MRV, there is no plastic insulating disk around the emitter). And that’s got to be one of the worse soldering jobs I’ve seen in awhile – note the bare exposed copper wiring at the –‘ve terminal. So why is the light not completely shorting out in my sample? Simple reason – the reflector is not screwing down quite far enough to touch the contacts, even with the bezel fully tightened.

EDIT: On further testing, it seems I was getting some shorting across the contacts initially. This was manifesting as a "flicker" on my low mode and strobe modes that was immediately resolved when I isolated the contacts from the reflector with some kapton tape.

In any case, the emitter is not properly focused within the reflector, leading to reduced throw. My measurements of overall output tell me the light is putting out more than my Q2-based lights – but throw @1m is no better than a Q2. See Beamshots below for a fuller depiction of the problem.

How about the further down the body? Here’s a shot of the contact board in the head (looking down the battery tube, since there’s no heatsink to unscrew). Hard to see, but there’s a rather messy soldering job in there.



And here are the tailcap threads. A bit messy, but they are anodized allowing tailcap lockout.



And finally the switch mechanism:



FYI, either my switch is unreliable or the emitter is shorting out on the reflector, as occasionally the light wouldn’t come on in my early testing - only flicker once upon pressing the switch and then go off.

I haven’t bother taking any additional body pics, but the type II anodizing is chipped off in numerous places along a lot of the edges of my sample, showing bare aluminum. The lettering is clear (although there is too much of it – every flat surface has writing on it).

Beamshots:

Quick and dirty comparison at ~1 meter from a wall, to show you the different overall spillbeam patterns. V-68C on the left (on 18650), Lumapower MRV Q2 (on primaries) on the right, both on Hi.






As you can see, beam profile is similar, but with a slightly wider hotspot and more defined corona on the V-68C. But that's not a good thing, as you'll see in the next couple of pics chosen to show you the effect of the de-focused reflector. These are taken close up at ~0.3 meters from the wall, on Low, to better show the hotspot.




As you can see, the reflector isn't properly focussed, even when screwed down all the way.

User Interface

• According to Kai's website, it's supposed to Hi - Lo - Strobe - SOS - off, accessed by clicking the switch in sequence. In fact, mine is Hi - Lo - slow strobe (2.5Hz) - medium strobe (5Hz) - off, with no SOS mode
• Light uses PWM for low mode, at a fairly high frequency of 467 Hz. But my light originally had a horrible low freq flicker on the low mode, separate from PWM pulsing. It seemed to be due to a shorting issue, as once I isolated the pill from the aluminum reflector the problem disappeared.
• The strobe modes are also very unsual - at first, they struck me as "reverse strobes" (i.e. rather being in "off" mode most of the time and flashing "on" for brief periods - like most lights - these strobes seemed to be "on" most of the time with a partial dimming "off" during the strobe sequence). However, after isolating the contacts from the reflector, this effect has gone away.
• Instead, I now realize that the duty cycle is exactly 50:50 on/off for both of the strobe modes (i.e. light is on half the time, off half the time). This is an unsual strobe mode, and not likely to lead to signficant improvement in runtime.
• There is no memory mode as such. If you wait more than 2 secs between clicks, light will revert to Hi mode.

Conclusions:

• I cannot recommend this light for someone looking for a turn-key solution to work well out of the box - it's going to require some effort to turn it into a useful light.
• Most important fix is to isolate the contacts around the emitter pill. My light had noticeable flickering issues on low and strobe modes that disappeared once this was corrected. Note that at least one user has reported frying his emitter on first use, due to a contact issue.
• Adding a lens o-ring would be a good second step. The 40 MM X 1.5 MM BN70 from oringusa.com is a good fit.
• You might also want to replace the lens with a UCL AR-coated one for improved light transmission. The 41.8mm UCL lens from flashlightlens.com is a perfect fit (it was developed for the MRV), and adds an additional ~2000 lux to the peak throw in my testing (i.e. UCL produces 17,000 lux @1m, compared to stock 15,000 lux).
• Replacing the circuit board might also be a good idea (if you can access it - I haven't tried). The two low freq strobe modes may not be very useful for most.
• Emitter is not well focussed in the reflector, as compared to the MRV lights on which this is based. The result is a slight-to-severe "donut" effect in the center, depending on your sample.
• Rear clicky doesn't seem very reliable in my sample.
• The body has a lot of superficial nicks, but does come with anodized tailcap threads (useful feature).
• Heatsinking is a big unknown (can't access it separately), but we can expect it to be nowhere near the capabilities of the excellent (and heavy) MRV heatsink.

As shipped, I'm afraid this light needs a little more work before it is ready for prime time.

But after isolating the contacts, replacing the lens and adding a lens o-ring, it is not a bad inexpensive thrower light. However, it remains to be seen if the heatsinking is adequate over a prolonged period of time.