Hi folks,
I've been commuting across the city here (in San Jose) for a while now, and lurking in the forums. Y'all have proven informative. Thanks a bunch for all of the tips.
I figured I'd write to say "hi", and share the geeking-up I've done to my commuter:
1) Headlights. I kicked around the idea of making my own, but when the Nite Hawk Dual Pro system came up for sale on Nashbar for $60-something (after coupons, before shipping), it was too good to pass up: the compact size, the pre-built switches, the quick releases, and the reasonably fast charger all come together to form a nice package. The system uses a 12V sealed lead acid battery which, while heavy, is at least user-friendly. I was looking at 12 SLA for any custom battery system I'd make, anyway. The bulbs are 12V MR11 halogens with 10 degree beam angles; one is 10W and the other 20W. The one I bought came with a helmet mount, along with an extra switch and wiring for it; I used that extra wiring to patch in my geek kit.
2) More lights! Using a 12V battery opened up the options here. I raided the trailer lighting section at West Marine, buying a bunch of low-profile sealed LED lights made by United Marine Inc. I picked up a taillight which has ten high-power red-orange emitters ("spider" LEDs?) in it, with lenses shaped into the clear plastic cover. This thing is
bright, and pulls 2-3W on high. I also picked up three amber side-marker lights, each of which has two amber emitters, and mounted them near the front of my frame facing left, right, and forward. Each of these pulls about 0.6W. While not as fearsome as the taillight, they'll still leave spots in your eyes if you look straight at 'em in the dark. I put one on the front to help with visibility, and to give me at least some signature from the front if my halogens are out for whatever reason. The rear light is West Marine #5344692, while the others are West Marine #5344726.
3) Flasher. I wanted the amber lights to flash on and off to draw attention, and I wanted the tail light to alternate between high and low intensity both to draw attention and to save some power. I tried a couple of different flasher modules from auto parts stores (including a "light duty" motorcycle one), to no avail. To address this, I whipped up a simple circuit to flash them at about 3Hz; since I was making my own, I left an option to hook up a brake switch that forces the taillight to high while the others keep flashing. It's all solid state; I'm sure the clicking of an auto flasher would've driven me nuts anyway. I mounted the flasher circuit under my rear rack; it's pretty inconspicuous, being about the size of a matchbox. First, I encased it in epoxy for shock and weather resistance, and then I wrapped it in black tape to make it less noticable.
4) Battery monitor. Just to be a nerd, I decided I wanted some sort of battery discharge status indicator. I considered a couple of different approaches -- the coolest-looking of which would've been a 10-segment LED bar display, coupled with one of the ready-made driver chips National makes for them -- but I decided I wanted to keep it as inconspicuous as possible, instead of having a big indicator sticking up somewhere. I ended up making a small circuit which drives a single dual-color LED to indicate the discharge state: off for high, green to indicate low battery (meaning, 15-ish minutes remaining with 20W halogens and flashers, 25-ish for 10W + flashers), and red showing a battery critical condition (meaning, turn the battery off ASAP to avoid damage). I shaped the circuit board so that it'd fit in my fork/head tube, and mounted the sole LED where a brake lever and shifter meet. It's practically invisible when it's off. The idea is that I'll get some warning before my battery poops out, and I'll have the option of cutting the halogens and limping along on LEDs only for quite some time, if need be.
Attached are some shots of the bike with its spiffy geek lighting. One really must appreciate the duct-tape-and-zip-tie mounting system.
It's tough to convey the effect of the lighting, since my point-and-shoot digicam fiddles with the light levels and colors, but one of the attachments shows the bike lighting from the front in an otherwise dark room. (All of that red light is from the rear monster reflecting!)
Stay safe,
-JAB