[Review] Cyansky K3 || Luminus SFT-40-W, 1600 Lumen, 1 x 21700 || Outdoor Beamshots, Output and Power Regulation Measurements

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bilakos10
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[Review] Cyansky K3 || Luminus SFT-40-W, 1600 Lumen, 1 x 21700 || Outdoor Beamshots, Output and Power Regulation Measurements

The flashlight was sent to me by Cyansky for review.
Here's the product's link: Cyansky K3 

The flashlight comes in a nice cardboard box.



Here's a closer look at the manufacturer's specifications.



The following accessories are included in the box:

  • Cyansky branded 21700 battery
  • Wrist lanyard (with some nice braiding!)
  • 1 x replacement tailcap boot
  • 2 x replacement o-rings
  • Pocket clip
  • USB Type-C charging cable
  • Carrying pouch
  • User manual.

The carrying pouch is made out of nylon.
The overlapping flap is secured in place via velcro, while a belt loop is present in the rear.

 

The Cyansky K3 comes with a black matte anodization.



The overall fit and finish is excellent.
Its body comes with parallel knurling for better grip.



The flashlight is dual switch operated.



The rear mounted, forward clicky switch is used solely for controlling the power on/off of the flashlight.



An e-switch mounted in the lower part of the head is responsible for controlling the mode switching.
The switch is made out of sandblasted metal and sits also flush with the surface of the flashlight.



A mildly crenulated bezel is in place to protect the glass lens.
Its worth noting that the bezel and head is a unibody piece.



Looking down the head, we can see a smooth reflector along with a Luminus SFT-40-W.
The centering of the emitter is perfect.



The driver seems press fit and glued.
A brass tab is used as the positive terminal in order to ensure maximum efficiency 



The rear switch boot sits below the two metal flaps, which allows the flashlight to tail stand.



The tail houses a copper spring.
The spring board is held in place via a retainer ring.



Here's the tail all taken apart.



And a  close up shot of the forward clicky switch.



Both the front and rear threads are square cut and are anodized, which allows the flashlight to get mechanically locked out.

 

A detachable pocket clip is also included.
The clip is quite stiff and provides excellent retention.



As already said, the Cyansky K3 comes with a 21700 battery.



The battery also includes a regular USB Type-C charging interface.



Once plugged in, a little indicator LED will shine up inform the user about the charge's state
green: full, red: charging.



User Interface

Being a tactical flashlight, the Cyansky K3 comes with a simple and forward UI.
Here's all the actions supported by the flashlight's firmware:

Turn on/off: Single press (rear switch).
Mode cycle: Single press (side switch) ( Low > Mid > High > Turbo > Low > ...)
Strobe: Long press (side switch)

Mode memory is present.
Low Voltage Warning and Low Voltage Protection is also present. The flashlight will flash 3 times whenever the battery gets low. I measured the cutoff voltage at 2.8V

Output

Here's my output measurements along with the respective current craw per each output level.



The Cyansky K3 push more than 1500 lumens at Turbo.
The manufacturer's specifications seem to be pretty accurate.
Mode spacing is excellent!

Power Regulation

Here's a power regulation graph that I've created for the K3.



What we can see in the graph:

  • Turbo's current draw is proportionate to the input voltage
  • High is fully regulated up down to 3.3V
  • Medium and Low are fully regulated for the whole span of the battery's voltage.
  • Turbo and High will stepdown to Medium once the battery's voltage < 3.3V
  • Medium will stepdown to Low once the battery's voltage < 3.1V 

Outdoor beamshots

And here's a few outdoor beamshots.

 
 

Bottom Line

The Cyansky K3 is a great tactical flashlight.
Its driver shows signs of great regulation and its Luminus SFT-40-W emitter is basically a dedomed SST40 and is great at producing a good balance between throw and output!

Edited by: bilakos10 on 09/26/2021 - 15:45
Rusty Joe
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Thanks.

My review mirrors your own and will be out soon. Mine seems to have artifacts in the beam, but beyond that, it’s a flawless light.

Rusty Joe
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I’d change the title from “K6” to “K3.”

TIFisher
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Nice review, sir. As always, love your beam shots….distances???

Noting the two solder blobs on either side of the anode nubbin on the driver, will the light work with flat top cells?

Dual switch is the real deal killer for me. I just don’t get the trend.

Sirstinky
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TIFisher wrote:
Nice review, sir. As always, love your beam shots….distances???

Noting the two solder blobs on either side of the anode nubbin on the driver, will the light work with flat top cells?

Dual switch is the real deal killer for me. I just don’t get the trend.

Those are interference bars meant to protect the driver from a cell inserted backwards. I tested this light a while back. No, flat tops do not work. Button top only.

bilakos10
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Rusty Joe wrote:
I’d change the title from “K6” to “K3.”

Totally mixed up the naming Smile Thank you for notifying me.
Looking forward to your review!

Rusty Joe
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How clean is the beam? Mine has some artifacts.

bilakos10
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Rusty Joe wrote:
How clean is the beam? Mine has some artifacts.

No visible artifacts on mine.
Is there a chance that your emitter is not perfectly centered?

Cyanskyflashlight
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Great review, thank you, Bill. Thumbs Up

Rusty Joe
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bilakos10 wrote:
Rusty Joe wrote:
How clean is the beam? Mine has some artifacts.

No visible artifacts on mine.
Is there a chance that your emitter is not perfectly centered?


Nope, it’s centered, but for some reason, there are some notable artifacts. Still a top-game light.
Sirstinky
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The beam on mine is clean.

Mark je do
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Good job, bro. Maybe add some pictures will be more interesting? 

Rusty Joe
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Mark je do wrote:

Good job, bro. Maybe add some pictures will be more interesting? 

Unfortunately, there is no way to do that on this forum without uploading to some online host since we can’t upload directly here. And some hate doing that (I certainly do).

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Cyansky have offered me this to review and I get excellent outdoor photos, so maybe wait for that.

Texas Ace Lumen Tube calibrated with maukka lights

New Zealand store – https://www.piercingthedarkness.co.nz (NZ customers only)

YouTube channel – https://www.youtube.com/channel/UCIUWi2vYp4CWrRkOJM70t_w/videos (Demos for my customers, and reviews)