KDIY KF8 flashlight (1x18650 XHP50.2)

LED Flashlights – General Info 18650 Flashlights
1

Today I got the brand new KDIY KF8 in. I bought the 5000K version, with Cree XHP50.2 J4 3A led. This is a 100% Kaidomain developed new flashlight, using a (as far as I can know) new design flashlight body edit: I'm wrong here, texas shooter pointed out that this flashlight is an unbranded Roche F8, it has KD's 20mm XM DTP-board and their H1-A 20mm boost driver. The cost is a moderate (IMO) 34 dollar shipped. I had been looking for a good compact host to use this driver and the XHP50.2, but then KD came up with this light that is exactly what I wanted to build. And I think that the design is really handsome! The design seems inspired on the Thorfire VG10 which I think is well looking too, but it is slightly larger with more fins, and I like it better because of the flat bezel:

If you open it up, the used components seems good quality, although the switch assembly is not ideal with all non-soldered contact points, the switch is a small Omten. The lens is AR-coated. It is a no-pill design. I started improvement by soldering brass cup-spring-switch contact plate together (with a bypass).

The ledwires are impressively long :

They are 24AWG, I shortened them by two-third.

Some performance.

I did some resistance reductions but that did not alter the performance, it will probably hold performance a bit longer upon draining of the battery but the driver nicely maintains a constant current.

The HA-1 driver has been discussed before on BLF, it is a single li-ion 3A (to the led) boost driver for 6V leds, has 4 nicely spaced modes with a good useful low (10 lumen) - med1 (250lm) - med2 (770lm) - high (1930lm). (own measurements on this flashlight)

What is great about this light is that it maintains the high output very very well, I did a 10 minute test-run on high on a 30Q battery without cooling: 1930 lumen at 30 seconds, 1830 lumen at 5 minutes, and still 1780 lumen at 10 minutes, that is 92% of the start-output . The head temperature was 72 degC by then (measured with an infrared thermometer on the fins), feeling hot but it is still a very safe operating temperature.

The battery current upon start with a fresh battery is 4.6A. after the 10 minute test run and after cooling down, the battery current was 4.95A , the driver copes with the lowered battery voltage by increasing the current, like a boost driver should. With the partly drained battery and cooled down flashlight I measured 1910 lumen output at 30 seconds, so this light really does compensate the battery drain well.

I did not measure led-current but based on my XHP50.2 output test, on high this should be about 2.7A, close to the specs of this driver. This current allows me to calculate system performance too, it calculates at 108 lumen/watt. For a flashlight close to 2000 lumen this is great, better than any other flashlight of this output that I have.

The beam shows a good even illuminated large white hotspot (as expected for a large led in a compact reflector), a yellow-ish corona (as we got used to with the new Cree leds) and bright spill. A semi-flooder. I may do a beamshot tonight but there's no surprises there, it is as good as you can get with the XHP50.2 I think.

Edit: here's a white wall shot at 2.5 meter (underexposed to show the hotspot well):

Conclusion: Kaidomain, this light is a winner!, it looks good, almost everything is very well done (except the switch assembly and long thin ledwires, but it still works alright so what do I complain?), the performance is good and stays good during longer use, and it is suitable for modding.

Edit: some extra bits of information in posts 20 and 21.

Disclaimer: bought this light from my own money, no affiliations with Kaidomain.

2

Thanks for the review mate! Looks like an awesome light. You sold me one already 2k lumens is plenty of output.

How do the 20mm KD boards handle heat? I have to buy some soon.

Run time on high would be about 20-30mins?

3

Thank you djozz. I want one of these now.

4

It is a DTP copper board, there is very little performance difference between the different brands, they all perform very good. What I did notice is that the solder mask of the KD boards peels off a bit easy, this is nothing problematic with normal use, it happened to me when sanding down one from 20 to 19mm and even then it was only the edge that came off a bit.

Runtime with 4.6A on a 3000 mAh cell like the 30Q should be 40 minutes or so.

5

Nice review, now you made me want one as well :person_facepalming: and I already have two XHP50.2 flashlights :laughing:

6

Very nice review!

7

Haha! Sold out already! I think you found a winner, thanks for the review.

8

I came across this light few days ago on KD and it really got my attention with the XHP50 LED it uses with that price. Thanks for the review djozz! I may grab one up later.

Is it possible to boost the current a bit more? Having a 2500 lumens pocketable light is something cool.

9

Yea, I saw this a week ago and was very close to buying it. Now I just might have to!

An extension for 2*18650 would be enough to put me over the top!

Thanks

10

This old C8 extension tube (I believe it was from Fasttech a few years ago) fits fine, same threads. It just makes no electrical contact in the middle because the threads on the KDIY light are anodised, you have find a solution for that.

11

Hummm, would have to change the driver to handle the increase in voltage but would definitely be a nice option if you wanted longer run times.

Thanks

12

Thanks djozz for the nice review. :+1:

13

The host is a Roche F8. Very solid platform. At one time the heads could be bought separate letting you lego a different drivers/head/LED’s onto bodies with only a few thread turns. It’s the cleaner version that P60’s didn’t evolve into. Tail caps often had built in cigar rings but not all.

14

Djozz great review!
Why did i even read this? Gotta buy one now…

15

Well spotted, thanks for the info, I will update the OP. I did not know it, I never had a Roche F8. This teardown of the Roche F8 by Ouchyfoot in 2013 (link) shows the exact same internals as well:

16

Thanks for the review! I was looking at the K5 from them, it’s sort of like a 26650 version of this one, little different body and head styling.

I actually bought that H1-A driver to play with and see if I can mod it into a convoy C8 with XHP50.2

17

Nice find, thanks for your thoughts :+1:

18

I found that in a small smooth reflector (Eagle Eye X7), the XHP50.2 shows some irregularities in the hotspot (though much better than the donuthole that the XHP50 makes), while in a 50mm smooth reflector it was alright. So I’d be curious what it does in a C8, it still may benefit from an OP reflector.

19

I have both OP and SMO on hand.

Also ordered the H2-C driver to play with. Will see what both drivers can do with resistor mods. My guess is they will probably be thermally limited unless they can transfer heat to the host, and getting much more than the stock 18W will be hard. Still nice to see some good boost drivers coming out. Now we just need more quality hosts with stock 20mm+ drivers.

Back to the KF8 though. I have a Roxane M6 with a very similar switch arrangement. Same orange Omten with the ring and pad contacts. Never liked that design much, especially if there is room for a proper PCB switch.

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I may go for the standard switch at some point, the brass switch container can be the source of a retaining ring by sawing a piece off, and just the height of the assembly must be guarded.

An extra piece of information on the driver:
I ran the battery down to 3.50V resting voltage, so well over half-drain, and measured current and output at 30 seconds. Current has increased to 5.6A now, and output is 1905 lumen. So the driver is still totally in control of the output! :sunglasses: Mind however that I did remove some resistances in the light, so the stock light may not get this result.