Mountain Bike Reviews Forum banner
1 - 6 of 6 Posts

11 Posts
Discussion Starter · #1 ·
So it's finally come to this, I've actually managed to build something that works...

Earlier in the fall I took on my first build, XP-E based, which turned out ok but the optics (from DX) were not what I had wanted and the unit weighed faar too much.

Just the lighthead came in at 100 grams, which was too heavy to put on the head.
I wanted something that would work both for running and biking and this didn't.

So I read some more and gathered inspiration. What really kicked off this project was Vancbikers microlight, composed of only two XP-Gs it was light weight and provided loads of light. Of course I wanted a little bit more light so four XP-Gs it was.

List of parts:
4 x Cree XP-G R4 on 10mm square MPCB from Cutter
4 x Carclo 10417 narrow lenses
1 x 1000mA BuckPuck
4 x 18650 Trustfire 2400mAh cells
1 x 4 cell battery holder from Luminous DIY
1 x 2 pole, on-off-on switch
1 x 25mm square aluminium tube from Ebay, 2mm thick
1 x 20mm aluminium L-profile, 2mm thick

First, damn those PCBs are small, I can get 4 of them onto the same area as I could get one of my old XP-Es.

So today I got to soldering it all together, which was a bit scary at first since my soldering skills are a bit rusty and these things are pretty small and fragile.

Also soldered the battery holder

Everything turned out ok in the end so I tried to power it on and then glued it to the L-profile using super glue with a dab of thermal adhesive in the middle of each PCB.

I then glued the lenses using bathroom silicone.

And here is the happy pack

The tube has not arrived yet so the kit is yet without housing.
I'm also using a potentiometer at the moment to control current, this will be swapped for the on-off-on switch combined with two appropriate resistors using this schematic:

No beamshots since we're currently having the worst weather I've seen yet this year. Very windy, about 0 degrees C, snow and rain.

467 Posts

Have you measured any voltages/currents? I am just curious how well the 4 cell pack powers 4 xpgs with a buck puck, as i have been considering building the exact same thing... mainly, voltage across the leds (all 4) at around 750 mA and the current its pulling form the batteries.

It looks great. I've been considering a very similar build for a helmet light and would like to stick with a 4 cell pack and a buck puck. Trying to decide on three or four emitters...


3,918 Posts
Based on my experience with the microlight, you are going to want to have fins on your tube housing. I don't recall the total area of the microlight but I think it was around 9 square inches. It gets up to 160-165 F very quickly in the shop on high. I have not used it yet on a real ride, just puttering around the property. It stays much cooler then. Those XP-Gs get hot at 1000 mA. You may be able to run lower current to help with heat.
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.