La vie de vélo

Adventures in cycling and life

DIY Bike light design, take 1

So I have an old 6 watt nightrider halogen hooked up to a lead-acid battery that has now been getting some use since daylight savings time. My nighttime commute is now pitch black. And while a 6 watt halogen and a blinky red led taillight are barely enough to keep me visible on the road, I need something more powerful. Something that commands respect and attention. Something that burns the retinas of any driver or pedestrian that would dare get in its path. Not to mention I’d like a light that can take me on technical trails for next years foray into 12 and 24 hour endurance mountain bike racing.

My ideal setup is simple: 1 super bright red taillight, 1 wide angle handlebar light, 1 bright narrow-beam helmet light. All the batteries must be rechargeable Li-Ion. Have to be swappable amongst bikes and have at least a 3 hour run time. Adjustable brightness is a plus.

I was looking at the Dinotte and Princeton Tec lights which are amongst my favorite of the cutting edge high-power LED lights currently on the market. But the price tags are pretty ridiculous. Which led me to start researching the potential for hacking my own…

So here’s the tentative plan for the front lights:

  • Night rider housings. I can reuse the old cases and mounts, just gut out the old buld and electronics. Since the casing and mount is probably the toughest part of DIY light design, I’m hoping this option works out.
  • Buckpuck LED Driver with potentiometer. This will take a higher-voltage batter and regulate the current to 700mA. The potentiometer will be retrofit into the nightrider case (somehow) to allow for dimming.
  • Cree MC-E LED on a star. This thing will put out 700 lumens at max current! One for the handlebar light, one for the helmet.
  • Optics.. haven’t really decided. Supposedly there aren’t that many good lenses or reflectors for the MC-E yet. I’d want a wide (20+ degree) for the bars and a narrow (< 10 degree) for the helmet.
  • 4.8 AH, 14.8 Volt Li-Ion battery. Probably pick two of these plus charger up from batteryspace.com. The single MCE should just suck down about 7 volts. Add another volt or two for inefficiencies and you need a minimum of 9 volts for the setup. But since the buckpuck driver can take up to 30 something volts, theres no harm in going with a larger voltage. This will give me well over 6 hours per light.

Total cost, approx $220 for the front lights. Still expensive but way cheaper than most commercial offerings considering the combo would put out about 1400 lumens!! Most of the cost is the big batteries.. maybe I could hack up some laptop or camcorder batteries for cheaper??

I don’t know exactly how I’ll tackle the taillight yet. But headlights first and we’ll see how it goes.

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November 10, 2008 - Posted by | Uncategorized

2 Comments »

  1. So many details…so many options!

    Comment by jawsome | November 10, 2008 | Reply

  2. Matt, take a look at GeomanGear. They have a super bright headlight with a li-ion battery for $85

    Comment by Norm Cotnoir | November 13, 2009 | Reply


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