Last weekend I finished putting together the dual Schmdit+Cree LED light. Lorah and I went on a 4 hour night ride and the light output rivals her $400 battery powered HID light. To say I’m never going back to the dual E6 lights would be quite an understatement.
I couldn’t have wished for a better result.
It’s constructed as two completely independent units to simplify the physical design and give me some redundancy.
I started with an aluminum tube and a piece of thick angle iron to use as a backing/heat sink for a Q5 bin Cree LED. The LED has thermal epoxy holding it onto the heat sink backing. I put threads in the backing and it screws to the inside of the tube with heat sink grease. The Lens is a Ledil smooth spot that fits perfectly inside the tube.
The electronics start with a Schottky full wave bridge rectifier, an on/off switch, high/low switch and nFlex constant current controller.
I used a high powered TIP3055 shunt transistor with 27V zener diode to keep the input voltage to the nFlex below its rated 30V. The tube itself works as a nice heat sink for the transistor. In testing I found the shunt kicks in at about 25.5V and at that point the LEDs have been at full power for a quite a while. I’ve run up to 8W though just the transistor on the bench with heat sink and it only gets slightly warm to the touch.
I didn’t use a capacitor to smooth out the rectification since even with a huge 1200uF capacitor I couldn’t see any difference in flicker with or without out. I figure one fewer part to fail on me.
All the internal connections are somewhat sealed and protected with heat shrink tubing so it’s unlikely that a solder join will come free due to it bouncing around. The parts are also packed so tightly inside that I don’t think anything even has room to move in there.
My test rig involved having my wife’s bike and my own upside down with her rear wheel up against my front wheel. I was able to hit 40mph in the living room before my arm got tired.
Total cost for each complete unit was about $75 for parts and materials. Of course, I spent way more than that getting various other parts to test with, and smoked a few items before I got it all right.
At 300mA output each light consumes 1.25W. At 1000mA output each consumes 4.5W. I only see the full 1000mA above about 25-30mph, so I leave them on high and they come up extra bright for descents.
The device should be rainproof. The switch caps are waterproof and the switches are sealed. I used silicone to seal the lens and strain relief, and JB Weld to attach the back cap. I haven’t tried dunking it yet. Maybe after PBP.
Update: After 3 days of rain on PBP I can say without a doubt that they’re completely waterproof, which is more than I can say for just about every other part of the bike
The beam pattern is about 15 degrees of solid white light with no hot spots that reaches about 100 feet in front of me. There’s a sharp falloff to the left and right of the beam pattern but there’s still plenty of spillover available to read signs and see around corners. I’d say about 80% of the light hits the pavement so it’s a very efficient pattern.
As with the E6 lights, having it on the fork allows me to see bumps and shadows easily.
I have a Cree helmet light that I used with the E6 lights to see outside its very limited trapezoidal pattern and on descents but with the Cree LEDs I didn’t feel the need to use it all.
Since it’s generator powered I can’t easily do an outdoor shot but here’s a beam shot as well as I could do indoors.
It flickers a bit between 2-4.5 mph and kicks in fully at that point. At 15mph its much brighter than my Light and Motion HID light.
The light is good enough that after PBP I’m going to leave it on and use it instead of my HID.
I was a little worried about it overheating but with the airflow from riding and the cool night air it’s cool to the touch even after long fast descents.
Additional assembly pics I took along the way are at
I’m still going to bring one of the old E6 lights with me in case something terrible happens, but I’m pretty confident that it will work out well.