I've finally upgraded the homebrew system I started in on two years ago. I have 3 main components:

Headlight
My primary light is a 30W Philips EnergyAdvantage (24 degree narrow flood) MR16 in an Optronics housing, driven by a 14.4V NiMH battery (4200mAh) from batteryspace.com. At this voltage I'm getting nearly 1200 lumens, in a nice broad pattern that illuminates the roadway very well, and somewhat brighter than the similar 35W bulb that I had been driving at 12V. I also stepped down from 5000mAH (C cells) to 4200 (subC cells) for this upgrade, so even with the additional cell count my new battery fits into a smaller case. After the first 10 runs or so I'm getting 80-85 minutes on a charge, plenty for my round trip commute and exactly what I would calculate based on the battery's rated capacity. My previous battery was very dependable in this manner, so I'm not surprised.

Battery is mounted in a CageRocket (thanks to this thread for the suggestion), with hole drilled in the side for a waterproof switch from batteryspace. Connectors are the very rugged "waterproof" ones from batteryspace. Unlike my v1.0 homebrew light project, which used quick-and-dirty but ugly crimp connectors, all connections on my v2.0 are soldered and shrinkwrapped.

Approximate cost to build: $140. $15 for bulb, $15 for Optronics housings, $50 for battery, $30 for charger, $10 for CageRocket, $20 for switch, connectors and miscellaneous supplies. And it blows away any commercial bike light I've seen for under $300.

Helmet light
I bought a Princeton Tec Apex as soon as they came out a couple years ago. The 3W Luxeon beam (60 lumens) is enough for the moderate nighttime mountain biking that I do, and for conspicuity even the 4-LED blink mode blows away the Princeton Tec Eos (1W Luxeon) light that I've had strapped to my helmet the last couple of years.

But I've been using the Eos (and charging its tiny AAA batteries 1-2x/week) because with its 4-AA battery pack on the Apex, there's just too much weight strapped to my head (especially with my past neck injuries). And besides, the cord from the light head to the battery pack is about 2 inches too short for elegant helmet mounting.

So last month, while working on the main headlight v2.0, I hit upon the solution: an extension wire that allows me to carry the battery pack in my pocket, and more connectors from batteryspace that allow me to quickly disconnect it from the helmet. Batteries are AA rechargeables, and in blink mode I seem to be getting enough burn time for more than a week's worth of commuting. Thumbs way up.

Approximate cost to build: $100. $80 for the headlight, $10 for batteries, $10 for connector and supplies.

Edit 12/14/07: I'm going to further upgrade the helmet light by replacing the Apex's 4AA battery holder with a 4.8V 2200mAh pack from BatterySpace.

Running lights
Yes, running lights. This was actually part of my 1.0 project, so I've been using these for a couple years now and they're working out great. I have four Piranha automotive LED side marker lights on my bike: an amber one on each fork leg, and a red one on each seatstay. Each of these is about 2" long, contains two emitters, is very bright and consumes around 1/2 watt:

I have four more of these units (in addition to $20 worth of DOT reflective tape) on my child's Chariot Sidecarrier trailer, with connectors that let me tap the trailer into the bike's running lights whenever I'm using it.

Driven by a little 2000mAh 12V pack from batteryspace that I've had for a couple of years (current model is 2200mAh), I get 8-10 hours per charge running only the bike's running lights (more than enough for a week of commuting), or 4-5 hours with the trailer hooked up. This battery pack is tiny (<300g), housed in a little canvas pack that I strap to the bike, and has performed flawlessly for nearly 2 years of year-round (yes, including summer) commuting. I'm not using a switch, since that's been a failure point for me in the past: I just plug the running lights in at the beginning of a ride, and unplug them at my destination.

Approximate cost to build: $100. $30 for bike LEDs, $30 for trailer LEDs, $20 for battery, $20 for connectors and supplies. This assumes you already have a charger.

Edit: here's a side view of the bike and light system (sorry no helmet light photos yet) on a bright overcast day. The glow from the front running lights is clearly visible, as are the big battery in the seat tube bottle cage and the small battery in the downtube bottle cage.



Most of you already know what the Optronics light head looks like, so I won't bother taking a closeup of it. Here's what it looks like head-on in broad daylight though: