Cofly KX-A036 flashlight, impression and teardown (+mod now)

LED Flashlights – General Info 18650 Flashlights
1

(a new day, a new flashlight brand :-) )

This flashlight caught my attention in the new arrivals section at dx a few weeks ago,

The Cofly KX-A036, a 1x 18650 (5 mode) zoomie, for 'complete' specs, see the dx-site.

Cheap ($11.36) and good looking, and finally a zoomie that has a sliding part that is not unnecessary wide for the tiny lens that is usually in it (exception: Uniquefire T20: big lens for its diameter). Sometimes those zoomies even have impressive cooling fins on the slider which is pointless, that is hardly where the heat goes.

I bought it and it arrived yesterday. It was a bit heftier than I thought, but I think the size is nice for what it is. A comparison to some other 18650 zoomies:

From left to right: Uniquefire UF-T20, Cofly KX-A036, brandless Sipik sk98 clone, Ultrafire ZB-something-cheapy-can't-remember, and again the Cofly KX-A036.The build quality looks much better than the sk98 clone and the flimsy Ultrafire, it feels really nice and has good modding options, but later about that.

First some thoughts on the optics. It shares the optical lay-out with the sk98 clone, the Ultrafire, and lots of other cheap zoomies: a lens with a focal length that is a bit too long to my taste for a zoom flashlight, which is a pity (exeptions: sk68, Uniquefire UF-T20, and just a handful others). Explanation:

A rough sketch, but actually drawn to scale, one square is 0.5 x0.5 cm. (the lenses are drawn a bit too thick actually, but that does not affect the point being made)

The Sipik sk68-and-clones have a very curved fat aspheric lens that gets the die projected in focus when at a very short distance from the led, it catches a wide angle of the light, even when zoomed in (same story for the Uniquefire UF T20). The Cofly/sk98/UltrafireZB have a flatter lens that achieves the right focus at a longer distance from the led, and therefore catches a smaller portion of the light (more light loss, less coming OTF). The throw (spot intensity) is actually not affected by the weaker lens, but the hotspot is smaller than it would have been with a fatter lens (but not brighter!).

I will try to find and fit a shorter focus lens for this flashlight to improve the performance.

The tail current that I measured with a fully charged Panasonic CGR18650CG is 2.86A, not bad for a stock light that is so cheap. Ceiling bounce lumen estimate: zoomed out 490 lumen, zoomed in 195 lumen (do not trust these numbers to be dead accurate, ceiling bounce measurements of zoomies I found sometimes give strange readings compared to reflector lights) . Projecting the hotspot next to a XRE sk68 clone (on a 14500 IMR 1.5A tail current) shows that the throw is less, but not extemely far off, which is nice for a XM-L zoomie:

The led die, as seen in real life (does not show well on picture), looks strangely rough and damaged, perhaps not the best batch of XM-L's is used for this light.

Tear down:

Inside the slider, looking at the back of the lens. Nice thin aluminium retaining ring: the lens is almost fully used.

Plastic led-board retaining ring, hard to remove! XM-L on 16mm board. Ample thermal paste under the board, nice.

A good solid pill with 17mm driver, not hollow: there is a whopping 3mm of aluminium under the led board! Lots of space inside the pill for any double/triple/quadruple whatever 17mm board. Big spring under the driver: the light accepts any length of 18650 cell, protected or unprotected, the thickest I have (with extra wrap for the protection board) are a tight fit.

I am not an expert, but this looks like a simple and effective direct drive board with PWM-controller. Nice touch: I can't detect any PWM on lower modes by waving the light frantically before my eyes: PWM frequency must be very high, as high as qlite (can't see that one either).

The body part where the pill screws in is thin, just as with the Sipik sk68, I used to worry about the heat not getting away from the pill, but in the sk68 is just appears not to be a problem, and I think this light is no different, it will do the job just fine. Nice amount of trapezoid anodised threading at the tail, well lubed, this can handle longterm use, and the light can be locked out. I hoped to have a look in the switch area too, but I found it impossible to remove the alu ring (I will try later with heat, but for now I will leave it at that). 14mm boot cap, the light I received hardly tailstands but others may be better, mine needs a lower bootcap.

Concluding: I like the looks and feel of this light very much and it seems well made, for $11.36 shipped IMO the price is excellent!

Next is modding it, I'll keep you informed :-)

2

Thanks for the review djozz. Looking forward to your mod.

3

I did the mod, I wanted a bit more than what I did, but it turned out it was going to be limited to a fairly straightforward led, board and driver swap:

XM-L2 6A1 80 CRI on Noctigon: dedomed ( taking warm white to a new level here ;-) )

Qlite revA driver with two extra 380mA 7135 chips stacked (10 total, good for 3.8A)

I tried again to open up the switch area, but did not succeed. Well, it looks well made so I'll live with that. I tried to find a 23mm aspheric with a focal length of 10mm instead of the stock 14mm, to improve the output zoom-out and hotspot size on zoom-in, and I am still searching :-( . At least the pill work I did very well (dedoming, stacking the chips, led-board with Arctic Silver5 straight under the led and two small blobs of Arctic Alumina Adhesive at the sides to glue the board down to the pill, extra solder blobs on the driver minus-ring to keep the board clamped inside the aluminium pill), no pictures of the process but it is the best soldering job I've done on a light thusfar :-) .

I like the outcome, these are the measured results ( I bought a second light, so I could nicely compare the mod to the stock light):

*(The lumen/watt numbers are zoomed out). So the lm/W number has gone down with the mod, not surprising with a warm white high CRI dedomed led (even though it is XM-L2). I have a Convoy M2 reflector light with a XM-L2 5B1 80CRI led that does 80lm/W at 3A, zoomies are hopeless in efficiency and I have made this one even worse than stock.

*The output zoomed out and zoomed in did not change much with the mod, but the mod needed 3.5 amps to get it, with 2.8A for the stock one.

So far the bad news.

*Good news one: (when zoomed in) the die image of a XM-L2 looks more acceptable than the die image of a XM-L

*Good news two: the light copes well with the heat produced by the led at 3.5amps, it warms up fast, gets hot, but works fine, no scary lumen drops when getting hot.

*Good news three: throw went up from 8.5 klux at 1 meter, to 21klux at 1meter (measured at one minute after switch-on); fairly good for this type of light with an XM-L2 led.

*Good news four: if you like warm white: dedomed 6A1 80 CRI dedomed is the one! Very cozy colour temperature (2500K?) with still very good colour reproduction, a bit better than my warm white household bulbs (which are up-to-date Philips bulbs), there's less yellow in it, more rosy. (I have dedomed a few high CRI lights now and my impression sofar is that if you start out with good CRI led, the dedomed version is not going to disappoint in tint and colour reproduction either)

Conclusion of the light/mod: I will never really be able to cope with the fact that the efficiency in zoomies is twice as bad as reflector lights, but I like this light in size, output and functionality. It will be my go-to light for camping trips from now on (well, until I find a new nicest light of course). It runs on high for an hour with the 3400mAh Panasonic I have in it, and that is alright with me.

4

Well done on the finished light. You will have to put the same led in the stock light with the dome on for a direct comparo now with pictures. :slight_smile:

5

Thanks, MRsDNF, I do have one of these leds leftover, but I think I want to make a warm white thrower with it in another host. Don't know what to do with the stock Cofly yet, something will come up one day, I'll update in this thread (with good pictures :-) )

6

I went ahead and bought this flashlight.

How do you mod this? And which parts did you end up buying? I want the most lumen output possible also retaining the strobe feature!
Thanks in advance :slight_smile:

7

If it is lumens that you are after, a zoomie comes not directly into my mind, there's considerably more light loss in a lens flaslight than in a reflector light. Zoomies are handy for two reasons: a nice even close-up illumination, and for making a intense spot for far away lighting. Reflector lights just give more lumens/watt than lens lights.

That said, the light in stock form has already close to maximum output, and incudes a strobe, it is a well done light. You can change the driver to one with a bit more output current, but actually compared to the stock driver, your gain will be perhaps 25%, not much more, not really noticable, you do notice the considerable shortened runtime of your battery.

With more succes you can mod it for more throw (much intenser spot when zoomed in) by using a XP-G2 led, perhaps even dedomed if you are into that. But it will cost you many lumens doing that, so more light in the smaller spot, but less light overall. But if it is a lot of throw that you are after, you could have got a different light with a bigger lens in the first place, like the Uniquefire UF-T20.

This light for me is a nice compromise in that it is pocketable and still has a good output, nice flood and a fairly useful throw. The ideal mod for me is putting in a dedomed XM-L2 and a Qlite driver with the 2 extra chips soldered on, that does (in my case) 3.5A current.

And I think the build quality is excellent for this price.

8

Ah excellent, okay I guess I will stick to the stock internals and just resolder it with thicker gauge wires.
It looks slim enough to be my tactical light, I will mod the switch and put in a pressure switch on it so I can mount it on my AR.
Thanks for the tips :slight_smile: I also bought a trustfire z8 hoping to use it as my pocket zoomie!

9

Hi DJ, any possible way to get more lumens out of the light with the current driver? my flashlight hasn’t arrived but I am worried it might be too dim for my liking. I have received my trustfire z8 and it is dimmer than my toptop $7 zoomie! Upset at the false lumen ratings… sigh.

10

A xml led at 2.8A is well driven, and 490lumens flood is not bad for a zoomie. And because of the bigger battery and better heatsinking it maintains the lumens much better than the Z8. This Cofly will throw a bit better because of the slightly larger lens. but it sounds like you want an output out of a zoomie that is not going to happen, even if you put in a beast of a driver, frying the h*ll out of the led+body, you will not even double the output.

About the driver, there is no sensing resistor that can be modded, there is no current limiting resistor, it is already direct drive with lower modes made by switching a fed. Just the resistance of the leads, traces and the fed limits the current here.

11

Right on, well the first thing I am going to do is replace the wires to a thicker gauge of copper wire.
Thanks! I guess super super bright zoomies are non-existent :frowning:
I am mounting it on my AR so I bought a pressure switch from wallbuy, hoping it will fit into the button cap on the cofly!

12

Could you please check if the diameter on the cap is 25.5 threads?

Thanks in advance :slight_smile:

13

I know nothing about thread sizes, but here are some measurements in mm:

So outsided diameter=2.25mm, inside diameter tailcap=21.7mm

14

Excellent, the pressure switch I bought will fit this flashlight!
Awesome… thanks for the detailed pictures. I will do a write up as soon as I get the light. DX is slow shipping! :frowning:

15

Hi DJ I got the flashlight, the driver just fell out of the pill already.
I see these tiny tiny wires, is it possible to upgrade the gauge to a copper wire? or will that fry the emitter?

16

Since it is a direct drive driver, every resistance you lower anywhere in the electrical path will lead to a higher current. But unlike common belief I do not think the stock led wires that come with budget lights are that much of a bottleneck. In the Ultrafire LZZ-15, that has a similar driver I measured quite some resistance in the FET (the current went up considerably when the FET was bypassed). So don't keep me responsable for any stupid ideas I have, but my guess is that thicker wires will not fry the led.

But do keep us updated ;-).

17

I am thinking of doing this, would it be overkill? The wires are much more than the original one, the original one looks like strands of needles.

Thanks for all the input! :slight_smile:
Gotcha, I am going to use my multimeter to see how much more current the flashlight is pulling.

18

Very thick wires handle a bit stiff, make sure they do not lift the led-board, a led board with air under it is the one best way to kill a led.

While you are soldering anyway, solder a thin piece of wire around the side of the driver (file the produced blob almost flat on the component side), it will press-fit the driver again and help with the electrical contact with the pill.

19

When you mean side, on the silver rim on the component side?

Also how did you remove the white plastic piece? It seems to be glued on…

20

What I mean is bend a piece of wire around the edge of the driver and solder it onto the minus-ring on both sides. But if you leave the blob thick on the component side of the driver, you can't press the driver in the pill anymore because the blob is in the way, so file it down to almost flat on that side.

The white plastic piece is a very tight press-fit and very hard to remove without destroying it. You could drill a small hole near the side, not too deep of course, and use a small screwdriver as a lever. But mind that the plastic piece is there to keep the led-board squeezed onto the pill, so if you remove it you must have an alternative plan for that, like using Fujik or better Arctic Adhesive to glue the board down.