Here is my first ever attempt at building a DIY LED light. After reading all of the back threads from probably the last three years here plus many other associated references, I felt like I had a reasonable idea of the sort of light I wanted to build.
First of all it had to be simple; I have no machine facilities apart from a drill stand. I also felt like I wanted to keep it reasonably cheap in terms of components – I didn’t want to be buying expensive drivers like the Taskled ones (great as they obviously are) and finding I had made an error in judgement due to my inexperience with designing and building lights.
I initially ordered one of the MTE SSC P7 flashlights from DealExtreme along with various other associated items such as 18650 Li-ion batteries and a charger, just to get a feel for what might be possible with the modern LEDs. I needed a new flashlight anyway and I figured the batteries would come in useful as well when I decided to build my own light.
After much deliberation I eventually decided to build the “Easy DIY” light first conceived by Citizen Kane:
The details of the build were well documented by CK, the case was easily available in the UK from Maplins and well, even Troutie had been moved to build one! What better recommendation could you have than that?
To cut a long story short I posted my initial thoughts on this thread:
Does This Make Sense?
With the excellent advice offered there especially from tamen00, I decided upon a 4 XP-G design wired in a 2S2P configuration using the Kaidomain driver known as“kennan” which would give a 500 mA supply current to each LED. This would give me 778 lumens from the 4 XP-Gs which I thought may be on the high side for road work but then again, what the heck! This is one time when more is more isn’t it? Using two 18650 2500 mAh batteries in series would give me a potential runtime I calculated, of around 2 hours 10 minutes before dropping out of regulation – more than enough for my purposes.
With the immanent release of the new XP-G I felt like the Hammond case was perfect for four XP-Gs in a row with the 10mm optics from Carclo. With delivery times from the other side of the world taking weeks I decided to order 8 XP-Gs from Cutters along with the Carclo 10417 Tight Narrow optics and the driver boards from Kaidomain just in case I wanted to build the Easy DIY version as well.
I was intending to build the light for road work (heresy, I know) which is why I went for all tight optics. Now that winter was approaching all of my night riding was on narrow, unlit, country roads in the UK (more of which later).
During the wait I set-to actually designing the whole thing in a CAD package I have and playing about with various options including exploring DIY battery case designs as well. During that process I started to consider different configurations of things including my own case and eventually came up with the cube design which I thought was actually quite cool. Inspired by odtexas’ brilliant bench saw, finning technique, I was also intending to experiment with this also (did I mention I have a bench saw?). Coincidentally I had done some cutting of aluminium angle in the past for something completely unrelated, so had an aluminium saw blade already as well.
With further experimentation with the designs I eventually came up with the idea using channel section for the body over a base where I could fix the all the components to. This seemed like a good option as it meant I could easily open up the case and get at the components if I wanted to modify or fix them.
Anyway here are the final details:
4 XP-G R5 on 10mm MCPCB wired 2S2P driven at 500 mA yielding a theoretical 778 lumens
Carclo 10mm XP range 10417 Tight Narrow
30mm x 3mm aluminium channel section with another piece of same cut down to angle section for base/back plate. 5mm thick slug glued to base with Arctic Alumina thermal adhesive. 2mm Lexan faceplate. I also created a ‘T’ slide for the Cateye mounting bracket which is fixed to the back plate with epoxy adhesive. I haven’t fixed the cover to the baseplate permanently yet as I am still deciding if I want to modify the construction.
Mounting bracket is a Cateye SP10 Flex Tight bracket which I just happen to have lying around from an old broken rear light. I really like the way this works though because it can be swivelled in both relevant plains to adjust the light direction very easily and fixes to all sizes of handlebar without any rubber shims that most other designs seem to need.
I tried to achieve a brushed aluminium finish using what we here in the UK call Wet & Dry paper. It didn’t come out too bad for a first attempt which hopefully you can see in the pictures.
2 x 18650 (2500 mAh) Trustfire Li-ion cells run in series to give a nominal 7.4V. Connects to light via 12V dc plug and socket on light. I constructed a “Dynamite” style battery holder which works really well and allows me easy access to the batteries for charging in a standard DX charger.
Kaidomain “Highly Efficient” driver generally referred to as kennan:
I hade my first ride with the light on the road on Tuesday evening. My initial impression was slight disappointment as although the amount of light output was literally a quantum leap from the Hope Vision 1 I had been using, the spread seemed a bit wide with not enough throw for the fast, road riding I was doing. After my usual two hour training ride I returned home and kept the light running to see what the actual total runtime would be. The light started to dim at 2 hours 15 minutes and I kept it running for another 15 minutes before removing the batteries and measuring the voltage at 3.21V and 3.18V.
Last night I scheduled my first ever off-road night ride and right from the off it was apparent that this was what the light was born for. Plenty of light and more than enough throw for the slower off-road speeds we were riding at. With an accompanying tighter head-mounted light this combination was more than adequate for all but the fastest descents.
I have noticed that in use the light does not get very warm at all even though the outer casing isn’t fixed yet. It might well be that I was a bit conservative running the LEDs at 500 mA and will probably up this to 700 mA. This will provide a useful boost to 1056 lumens solely for off-road use but this will also reduce the runtime down to about 90 minutes so I might have to up the battery pack a bit maybe to 3 cells which is no problem as this driver can handle up to 18V.
On reflection I think that box section would give a better overall finish to the light and I have decided that I would have preferred to have the mounting on the bottom of the light rather than the back. This would make the light sit up slightly higher and make tightening the Cateye bracket easier.
One thing that has happened on a couple of occasions is that the plug from the power lead has caused a bad connection both on and off road, causing the light to go off. The plug has not come out of the socket just come loose. It may well be that the plug and the socket which were sourced from different suppliers may not be an ideal fit. With the proposed shift in mounting bracket that I highlighted above I would probably dispense with the connecting socket altogether, preferring to bring the power cable straight out of the back plate as many builders here do already.
I have been very pleased with the outcome of this light in so many ways. The sheer pleasure of designing and building a light of this power which would shame most of the commercial offerings on the market for a fraction of the cost is something you can’t put a price on. Also the ability to tailor the package to exactly meets your needs is also something very difficult to achieve with commercial lights unless money is no object.
I will probably make the modifications outlined above and keep this light solely for off-road use. I am already planning a tighter beamed light for my roadie jaunts and also to double as a headlight off-road (yes, I’m hooked). I already have orders for two versions of the Picasso light from my friends as well so I should be busy over the coming weeks!
I would like to thank everyone who has contributed to making this forum such an interesting and informative place. Not just those who have helped me directly, but I have taken inspiration and encouragement from almost every post here in one way or another.
Oh yeah, if you hadn’t worked out my pretentious light name by now, here’s an extract from Wikipedia:
Pablo Diego José Francisco de Paula Juan Nepomuceno María de los Remedios Cipriano de la Santísima Trinidad Ruiz y Picasso (25 October 1881 – 8 April 1973) was a Spanish painter, draughtsman, and sculptor. He is one of the most recognized figures in 20th-century art. He is best known for co-founding the Cubist movement and for the wide variety of styles embodied in his work. Among his most famous works are the proto-Cubist Les Demoiselles d'Avignon (1907) and Guernica (1937), his portrayal of the German bombing of Guernica during the Spanish Civil War.
(with apologies for the length of post and the crap beamshot – no manual setting on my compact camera)
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Thread: Picasso Light