Review: YEZL T9 "Flood to Throw" Zooming XML Light

The switch in mine began to fail and I pretty much destroyed the tailcap getting the switch out. It was some really crappy designed pressed/locked in switch. It was the first light I ever had with this type of switch.

To dissasemble it, the best way is making two small holes on the plastic ring that retains the switch, and then unscrewing it.

Unfortunately it has now become a donor light. I really liked the light for its flood. I ended up taking the XML and driver and swapped it into a really cheap Tractor Supply 3xAA light. It now runs on a 26650. Its kinda of a poor mans JM07 lol.

I just got mine. I may look for a Fresnel or thicker lens for it.

It gave out after a few minutes of testing, before I figured out the modes. Probably the electronic driver failed, but I am not sure it was not the led or connections. Maybe the driver could not take the rapid switching when I turned the tail cap. The treads are anodized but a bit rough.
Now I have replaced the led with a warm white T5 XM-L2, and the driver with a 7135 x 8. I smoothed the tail cap threads and wrapped a bit of paper around them to make it work as a twisty, replaced with duct tape. The tail button switch only momentarily interrupts to switch modes.
It does out throw my Raysoon TD-398 SK-98 clone with the same driver and its original T6, with a much smaller and moderately brighter spot, as expected from the first order optics. (The optics logic goes as follows: If you scale up the lens with the same focal length to diameter ratio, the throw increases because it catches the same amount of light but focuses it to a smaller sport. The Yezl has a longer focal length than that, which, in the limit of small diameter to focal length, does not change the throw but only makes the spot smaller.) Flood is right about the same.
I have a thicker lens of the right diameter, but it is too thick at the edge for the bezel to hold it on. As expected, it gives similar throw with a larger spot, on the ceiling because the bezel does not hold it in place. If I had a lathe, I could extend the step back farther into the moving head to make room for the thicker outer edge of the lens.
I was not able to find a short focal length Fresnel lens of near the right size. Apparently stage lighting is the only thing they are used for, and those are too big. Based on my earlier tests, that would be the ideal solution.
I still love the shape and most of the workmanship. I feel I have made enough pottery and jewelery to know a nice shape when I feel and see it. Fins would be silly on a light with such a big head. I ordered a UniqueFire UF-T20, which according to Any info about UniqueFire UF-T20?, performs better, but from the pictures it looks ugly. Maybe I can cannibalise its lens.

TangsFire C8, Yezl T9 with XM-L2 and 7135 x 8, Raysoon TD-398 with 7135 x 8.

Here is the knurling, using the light’s own lens to shorten the focus of my digital camera.

I seem to be finally making progress. The “38 mm.” lens from DX is 38.3 mm and does not fit, but the very similar lens from a UniqueFire UF-T20 does fit, and the DX lens fits in the UF and works. The problem now is that the bezel of the Yezl won’t fit over the UF lens, but I can get a half round file and make it fit. The UF is pug ugly and has very poor flood, but it is nice not to have to degrade it to get its lens.
(An expensive lens I ordered does not fit because it is too thick at the rim, and a lens blank I got from a surplus store is not even short focal length.)
Added: The reason the expensive lens does not fit well is that instead of having a flange around the outside, it has a (sort of dead) 38 mm. cylindrical thickness next to the flat face. So its usable area is a couple of mm. larger than that of the others. If I attach it to the sliding head with solvent glue and no bezel, I will have a slightly larger area of lens with an only slightly longer focal length than with the UF-T20 lens.

I filed the bezel and it works.

The Yezl with the UniqueFire lens, right, vs. the UniqueFire with the DX lens, left.

The long zoom movement with the short focal length lens makes very small spots at close range possible, but I can’t think of a use of it.

Only the reverse intermittent tail switch remains an imperfection. It works fine as a twisty, but duct tape is not an elegant solution. Maybe I will wait till I get the second one I have ordered before fooling with the tail.

Added: I filed about a mm. off the back of the sliding head to increase the flood.

My second one finally arrived. There was a brief period when it didn’t work. Maybe the tail wasn’t connecting. I have still not figured out the modes of the electronic switch driver controlled by momentary interruptions in the power. The build seems even better than that of the first one, because the tail cap threads don’t have projections that bypass the switch when it is being screwed on.
Added: This one is from Computer T’s store on AliExpress, http://www.aliexpress.com/item/Yezl-T9-CREE-XM-L-T6-1x18650-Zoomable-Flashlight-Big-Head-Flashlight/1520701179.html. It is cheaper than the one from CNQ and also a better example, because of the tail threads. They do make contact when the head is being screwed on, but not as much. It can be locked out by unscrewing the tail cap.

There should be more documentation on the mode control. All I have been able to find is four stars of decreasing brightness under “on” and ” 1 / 3 / 9 Hz / SOS ” under “off”, engraved near the switch. That seems correct but doesn’t tell me everything. There is a user selectable level, where it gradually changes brightness until the switch is pressed to select a level. If it keeps working long enough for me to figure it out this time, I think I will like it. Unscrewing the tail does lock it out on this one.
It does not fit protected cells, and I don’t know if it has low voltage protection in the driver. I didn’t see a coil on the broken driver from the first one, so the battery is protected by the led’s forward voltage.

As the tail cap says, the steady modes are reached from on and the blinky ones from off. It seems to have no memory. One click from off turns it on high. One click from any on state turns it off. Two clicks from high turns it to medium. Two clicks from any other on state turns it on high. Three clicks from high turns it to low. Four clicks from high cycles the brightness, and a click selects a brightness from there. This does not seem to be remembered.
Two clicks from off turns it to 1 Hz. blink, 3 clicks from off to 3 Hz., 4 to 9 Hz. and 5 clicks to SOS.
In case we are bored with this simple behavior, three clicks from medium or low turns it to 1 Hz., 4 clicks to 3 Hz. and 5 clicks to 9 Hz. There seems to be no way to reach the low steady modes from any state without going through high, not good for retaining night vision.
With an old Tenergy cell charged to 3.9 V, I read 1.8 A, 0.8 A, 0.4 A and cycling.
When I focus it to a small spot and wave it in circles on the ceiling in low mode, I see dots from pulse width modulation, but this has not been noticeable until I looked for it. I don’t hear any noise.
So this is a very versatile driver, but probably too complicated for most users, especially with only the documentation etched on the tail cap. I like it and don’t expect to replace it unless it brakes, as the first one apparently did. I only plan to change the lens (though it does have better flood than the one with the short focal length lens).
This is the best flashlight I have ever bought and about the second best I have.
Added: It does have some memory. The only thing I have found it remembering is the pick-your-own brightness mode. It doesn’t remember the choice, but it goes back to cycling when I turn it back on.
Added later: The driver’s user interface is documented in the description of the Yezl T91 Loading.... The only difference appears to be a charging port, but there might be quality control differences.

> Two clicks from high turns it to medium.
> Two clicks from any on state turns it on high.

Does that mean “Two clicks from on-anything-but-high turns it on high” ?

Yes, thanks, I fixed that.

An other reason to change the lens is that the one that came in it is spherical or nearly so. The outside is more focusing than the center. This results in a larger spot outside the main one at full throw, which is not bad. It probably works better than a perfect aspheric at full flood. But partially zoomed it makes the outer part of the spot brighter than the center, which is bad.
The one I got from AliExpress is less focusing at the edge, which is likely a reasonable engineering compromise. It makes a larger spot or halo around the main spot but the main spot is uniform. The main spot led image is about the same size as that of the UF-T20, so the center has the same focal length, even though it has no flange so that the active part is wider.
Added: I put the $27 AliExpress lens on it with old fashioned Duco Cement. Seems to work great. Not an ideal sharp focus aspheric, but it works well. The whole 38 mm. width transmits light, and, depending on the zoom, most of it contributes to the spot. There is a brighter edge on the spot at some zooms.
This is my best light now.

The switches of the new ones appear to be held in by aluminum disks that form the negative contact, but I will try drilling holes and unscrewing.
I drilled two holes and applied quite a bit of torque with needle nose pliers and no movement. It now appears that the whole tail cap is a solid piece of aluminum with only the switch boot and a small hole in the center that the spring comes out of, and the anodizing cut away where it contacts the end of the battery tube.
Maybe there is something better than pink duct tape to put on the threads to make it lock out to be a twisty. The intermittent switch with the Q-light driver only serves to change modes.

My second Yezl’s driver went out when I put the cell in backward. Apparently no reverse voltage protection. I replaced it with a Q-Light set for the moonlight group. I de-domed the led while it was apart. I kept the original led, rather than trying my first de-dome on a fancy new one. It draws 2 A with a good 3.8 V cell and out throws the other one.

The $27 lens came out easily after leaving a little acetone around the lens to soften the Duco Cement while it tail stood for an hour.

27$ lens and de-domed original XM-L on left, UniqueFire lens and warm XM-L2 on right.
1.6 A on the de-domed XM-L and 1.2 A on the warm XM-L2.

The former draws 3.05 A on the cell charged to 4.2 V.

I got the switch out of one of them.

It is 9.4 mm. in diameter and is forced in place from the outside. A plastic ring is forced in also from the outside to retain the boot.
So I need a 9.4 mm. diameter switch that turns off, not just momentarily interrupts. Or a tail cap with an on/off switch.

I found that the switch from a Black Cat fits and works. I have not been able to buy switches separately that fit, so I ordered two more Black Cats, one from Fasttech for $8.50 https://www.fasttech.com/p/1387212, and one from KaiD for $8.00 http://www.kaidomain.com/Product/Details.S008793. The FT one is to replace the one I just cannibalized. Not all the Black Cats from KD work out of the box, but they are 50 cents cheaper and the switch should work in the other Yezl. $8 doesn’t seem out of line to replace the switch in a light that I consider to be a bargain at $17.10 and that has a $27 lens on it, plus an XM-L2 and a Qlite. Nut Lights and Warsun X65s out throw them for way less cost, but they are almost as ugly as Unique Fire T20s.
I don’t mind twisties, but the day glow imitation duct tape gets loose after a while.

In one, I have a Black Cat switch, an XM-L2, a Qlite driver and a lens from a UniqueFire UF-T20.
In the other one, I have the $27 lens that is so big it has to be glued in. I now put an XP-L High Intensity LED (“Cree XP-L HI U6-5A 380LM 4000-4500K LED Emitter”) and a BLF A6 driver from Banggood in it. Astrolux S1/BLF A6 A17DD-L FET+1 2.8-4.35v 7/4 Modi Taschenlampe Treiber Sale - Banggood Deutschland-arrival notice-arrival notice. It is almost, but not quite, as bright now as my CNQ with a Nichia 219C. It out-throws it though. Fasttech is out of Black Cats, and the KD one has not come yet, but, with the 3 ma. moonlight mode of the BLF A6, I can use it with just the intermittent off of the original switch, as long as I don’t store it for weeks with the battery in it. Or the battery test / beacon mode has even less battery drain.

Left to right: Yezl with UF-T20 lens, Yezl with big lens, CNQ with Ahorton lens

Added: The Black Cat came. I had to glue the switch in, as it is too small for a press fit. I destroyed the rubber boot when taking the plastic ring that holds it out, because I didn’t know that the ring is screwed in, not force fitted. This time the ring is in tact, but I can’t find a boot that fits.