KDIY KF8 flashlight (1x18650 XHP50.2)

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djozz
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KDIY KF8 flashlight (1x18650 XHP50.2)

 

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 surprised :

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 cool . 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.

 

 

Edited by: djozz on 05/05/2017 - 19:00
everydaysurvivalgear
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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?
ImA4Wheelr
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Thank you djozz.  I want one of these now.

djozz
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everydaysurvivalgear wrote:

How do the 20mm KD boards handle heat? I have to buy some soon. Run time on high would be about 20-30mins?
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.

khas
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Nice review, now you made me want one as well Facepalm and I already have two XHP50.2 flashlights LOL

firedome
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Very nice review!

<p>“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.</p>
<p><a href="https://en.wikipedia.org/wiki/Plato">Plato</a></p>

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

bibihang
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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.

bikenber73
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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

djozz
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bikenber73 wrote:

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

Thanks


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.
bikenber73
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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

MRsDNF
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Thanks djozz for the nice review. Thumbs Up

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

texas shooter
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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.

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

Budget Light Forum ...where Frugal meets with Flashlight!

 

djozz
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texas shooter wrote:
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.

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:
Jensen567
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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

CRX
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Nice find, thanks for your thoughts Thumbs Up

djozz
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Jensen567 wrote:
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


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.
Jensen567
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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.

djozz
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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! Cool Mind however that I did remove some resistances in the light, so the stock light may not get this result.

djozz
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I found an extra negative for this light: when the switch assembly is screwed really tight, the way I like it, the battery tube does not make electrical contact with the tail (a common fault with these tail designs). So it needs the paperclip treatment Sad (I used a stripped and bend piece of 20AWG wire filled with solder instead).

khas
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Jensen567 wrote:
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

The Thorfire C8s uses a 19,6mm driver very easy to fit the H1-A driver :

http://budgetlightforum.com/comment/1106082#comment-1106082

KeepingItLight
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Great review.

Every so often, I read that the big explosion in flashlight technology has already tailed off. The biggest jumps in output came at the beginning of the LED revolution, when flashlights went from somewhere around 80-100 lumens up to about 500, and soon thereafter, to 700 or 800.

I gotta say, I just don't buy it.

When you can get a 2000-lumen light like this for only $35 USD, I say the game is still on!

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Hi djozz, thanks for the great review! I have been eyeing this light for quite a while already and glad to know that it performs pretty well. Smile

Did you try to stack an R100 resistor and see how much output it can give?

Edit: Jensen has tried it here and the results look promising. Adding an R100 seems to have pushed the driver to its limit already tho.

djozz
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No, I did not do the R100-mod yet. I may first wait for a good highCRI XHP50.2 to become available before I start modding this light Smile

bibihang
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Yeah that’s good too. I am not sure if these newer XHP50.2 tint is really bad or not, haven’t seen one by myself yet. So in your opinion is the tint really bad?

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Thanks for the review djozz. Looks like a nice flashlight. I read on the Kaidomain website that it has a “Low Voltage Warning: It will keep flashing when the voltage is below 3V.” Do you know if it eventually turns off, or does it just keep flashing?

I’d rather use my flashlight around the house than turn on the lights.

djozz
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bibihang wrote:
Yeah that’s good too. I am not sure if these newer XHP50.2 tint is really bad or not, haven’t seen one by myself yet. So in your opinion is the tint really bad?

I’m just not too fond of cooler low CRI tints, and in combination with a less than perfect beam and some tint-shift over the beam makes this light not my favorite. But in a 90CRI 4000K tint it get ways more attractive. Let’s see if that will become available somewhere, I hope for KD.
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Thanks for the review Jos.
Hmmm, looks better than the Haikelite I planned to buy (sold out already). I’m getting more into boost driven FL now for their flatter runtime. The Haikelite MT01 wins in battery capacity while KF8 is more EDC-able.
Can you please measure the reflector largest width and height for me? If my Gaggione TIR fits in, then this could be my next toy.

- Clemence

djozz
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I will do reflector measurements and check low voltage behaviour when I’m home again, perhaps I have time on monday.

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djozz wrote:
I will do reflector measurements and check low voltage behaviour when I’m home again, perhaps I have time on monday.
Thumbs Up Smile

The regulation seems very good, should be even better at lower current. I’m not a big fan of brute 2000+ lumens. A well distributed 1000 lumens (purpose specific) is more than enough for outdoor uses while 300ish lumens is the most useful max for daily uses.. Wondering how efficient this boost driver really is. Let’s hope it’s higher than 88%

- Clemence

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