Skylight's 12th BLF Old Lumens Contest Entry - Modified flashlight [finished]

Giveaways and Contests
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The flashlight is finished now: Picture gallery

In the last two days I started a last minute project for the modified flashlight category. It is almost finished but let me present it step by step.

As a host I chose the Starfish X40 which I got from Taobao. The head is a little smaller than the head of a Convoy C8+ and it uses a 21700 battery.

I am going to use three XHP70.3 HI, a triple reflector of the Imalent MS03, a copper spacer and a Convoy 6V 8A boost driver. One XHP70.3 HI is missing in the following picture:

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First, I cut the 16mm copper MCPCBs smaller with a hacksaw and side-cutting pliers.

Of course I also filed the edges to make them flat and smooth.

I did a little test fit of the copper spacer, the MCPCBs and the reflector inside the flashlight head.

I removed the two XHP70.3 HI 4000K 90CRI from their original 25mm MCPCBs and used an additional XHP70.3 HI 4000K 70 CRI (N4 5D from Convoy).

I reflowed the leds onto the MCPCBs.

Leds and reflector

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Now comes an interesting part of this mod. I decided to bake the flashlight on my hotplate because I may get the same flashlight host again and the contest flashlight has to look special.

If you bake a black flashlight, what is the resulting color? Brown, right?
Well, not this time. This flashlight decided to turn GREEN! :grin: :alien:

I disassembled everything and reassembled it after baking.

The baking took about two hours. I had to bake all three parts separately and aid the process with the hot air station because the hotplate is not powerful enough to heat the parts to over 300°C. The photo on the hotplate is staged with all cold parts.

I soldered the two parts of the copper spacer together with 180°C leaded soldering paste. Instead of the 2mm thick copper disc I wanted to use originally I switched to a 1mm thick copper piece, cut to the right size with the hacksaw.

Next, I soldered longer 22AWG wires and a spring to the 6V 8A boost driver. Also, I soldered the three XHP70.3 on their MCPCBs to the copper spacer using low temperature lead-free solder paste.

I connected the three leds in parallel.

This part was challenging because the reflector sits directly on the MCPCBs, so the soldering has to be as flat as possible. Even the 22AWG cables were too high. So I used some copper tape and Kapton tape or isolating tape to prevent shorts.

The last step, the final assembly, was tricky to say the least.

I drilled the cable holes in the shelf a little bigger and also filed a little notch in the copper spacer to make the cables fit.

Before and after with thermal paste

I covered all the soldering with Kapton tape to prevent shorts.

I had to remove the reflector again several times because of short circuits and bad contact. The space is very constrained and there are only few millimeters space for the wires around the reflector. I can tell you that working with bigger flashlights is definitely easier. The only advantage was that the reflector didn’t turn when tightening the bezel. That is also one of the reasons I used domeless leds because the XHP70.2 could be easily have their domes ripped off by the reflector.

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My modified triple XHP70.3 flashlight is now finished. I’m glad I baked it because I really like the green color. :sunglasses:

Here are some photos of the finished flashlight:

Comparison, from left to right: Triple XHP70.3 flashlight, Convoy M21B, Convoy C8+, Sofirn SP33 V3.0

Concluding with a nice GIF:

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This post is dedicated to beamshots.

First the whitewall beamshots:

The tint is quite neutral thanks to the rosy influence of the XHP70.3 HI 5D. Apart from having only two XHP70.3 HI in 90 CRI this is the reason why I added one in 70 CRI as only 90 CRI would be quite greenish. The green AR coated glass lens helps as well.
The beam has some strange rings around the bright hotspot. There is a dark ring around the hotspot, followed by a bright ring and then the spill. It is less noticeable outdoors. If it bothers me too much I have some DC-fix on hand.

From left to right: Triple XHP70.3 flashlight, Convoy M21B with XHP70.2 5000K 90 CRI, Astrolux MF01S SST20 4000K

From left to right: Triple XHP70.3 flashlight, Convoy C8+ with XHP50.2 5000K, Sofirn SP33 V3.0 with XHP50.2 5000K

Now the outdoor beamshots.
Settings: 4s f7.1 ISO400 (A little brighter than the usual 2.5s)

Control

Moon

Low

Med

High

Turbo

Animated

Comparison with other flashlights

Sofirn SP33 V3.0 with XHP50.2 5000K

Convoy M21B with XHP70.2 5000K 90 CRI

Convoy C8+ with XHP50.2 5000K

Animated

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The beam of this triple XHP70.3 HI is not only floody as the small reflector indicates but it also reaches out to a distance of around 100m. The ringy beam is not that visible outdoors. The Cree HI leds really have a greater throw compared to the HD leds. Their disadvantage is that they can produce ringy beams or donut holes. On the other hand, they have no tint shift.
The XHP70.3 could handle a stronger boost driver because each led gets only around 16W. I could have used 2S direct drive but this small flashlight can’t handle that much power anyways. Also, a 21700 cell has more capacity than two 20350 batteries and with a boost driver it runs more efficiently. If the XHP70 3V wouldn’t be that expensive and hard to source one could use three 3V XHP70 and direct drive for 12 000+ lumens. :sunglasses:
As I already have enough 3V XHP50.2 flashlights, I have learned to prefer efficiency instead of a only few seconds Turbo. So, the goal was to build an efficient flashlight with good tint and CRI. You have to add a bit of diversity to the collection, right? :wink:
I didn’t try what brightness this flashlight could sustain. In the beginning, it does not get hot immidiately because of the copper spacer absorbing the heat first.

I would like to conclude this build thread with many thanks to Hoop, the sponsors, the judges and everyone who makes this competition possible! :+1: :flashlight: :+1:

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That´s a lot of effort to fiddle in the LEDs. I like the green color, it looks a bit like a Army Style Flashlight now.

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That green looks amazing!
Never seen that happen before!

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Great job! I love that reflector

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Just 5 minutes before I noticed this topic, I spotted the Starfish X40 on Aliexpress and I was instantly intrigued by it! :smile:

Where you actually able to buy it as a host on Taobao? On AE I can only find 1 seller who lists it, but only as a complete flashlight.

I already liked the somewhat more unsual look of this light, but DAMN, that green color after baking it turned out AMAZING! A beautifull (and dark) hue of green, I love it!

Is there a reason by the way that you used (stayed?) with 22AWG wires, instead of going for 20AWG (or maybe even 18AWG?). 22AWG should possibly be enough for roughly 48 watts though, but when you’re at it, why not change it for 20AWG?

All in all a really cool project and result!

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Thanks for your nice comments, GorgTech, INeedMoreLumens, worrub918 and Wingman. :smiling_face:

Yes, the green is indeed awesome. The battery tube is a slightly different hue of green. I could have stopped a little earlier and the green would have been darker but I like it as it is.

If you choose the cheapest option, that is the host. Here is the Taobao link: Starfish X40

You are right about the wires. I thought about switching to 20AWG wires like I normally do when possible. However, in this flashlight the spacer and the reflector left very little space for the wires. I already had a hard time making the 22AWG wires fit. The soldering joints had to be as flat as possible and the wires couldn’t go higher up than the leds, not even at the edge. Bigger flashlights are definitely easier to work with in terms of available space.

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Great mod Skylight!

Nice job on cutting the MCPCBs and soldering them to the copper spacer. :+1:

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Ooh that green… :+1:t4:
Congrats with the mod @Skylight

:flashlight:Cheers

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