Longtime rider, but new to these forums, and what a great thread! I've learned a lot already Could you guys critique my planned build?

I'm currently running a TurboCat S25headlight (10W+15W MR11s at 6V) plus the usual assortment of blinkies, LED headlamps, etc., but would like to upgrade to a homebrew system. Having entirely rewired my previous home, I'm quite comfortable working with electrical stuff, though I still definitely want to keep the system as simple as possible while still getting the functionality I'm looking for. After reading the Starlight 78 page, I'm thinking of putting together a 12V system with the following components:

- 20W MR16 high beam (which would be on most of the time), using the Optronics holders. In a living room test, an el-cheapo GE 20W MR16 (that doesn't seem that well made) noticeably outshines my current 25W system, and I expect the Philips energy saver 20W to be substantially brighter.
- Two Night-Sun Xenon strobes, amber front and red rear. 12V version, since they go through batteries pretty fast.
- Luxeon III low beam. Still working on how to make this work, but I have a Princeton Apex headlamp using the same emitter and I'm impressed with the output for situations where I don't need a ton of light.
- NiMH Battery pack in the 4000-4500 mAh range. Although it would be tempting to over-volt to bump up the output of the high beam, I'm thinking of sticking with 12V because a lot of the12V-ready LED products I've seen look like they wouldn't be able to handle the extra voltage.

Looks like with everything on, this system should draw just a hair over 2 amps from the battery, for a theoretical burn time of nearly 2 hours, though I realize actual burn time may be a bit less. My evening commute is only an hour, but I've heard NiMH batteries don't like being drained much harder than that, and if I push them harder I might not end up running my lights optimally. So it seems like a good idea to have a little "extra" battery capacity.

Also, here's an interesting question. After reading about people hooking up horns, cellphone chargers and other 12V car-like accessories to their light batteries, I got to thinking about cars' electrical systems, which hook the negative terminal of the battery to the frame, requiring only 1 wire to be run to each (grounded) component.

So why not do the same thing on a bike? It would be really elegant to run a single wire to each component, with each item's other pole firmly grounded to the bike frame. Anyone tried this? Since my front lights would be attached to the handlebar, I'd be running about 2A of current through my expensive King headset. Would that damage it? Or would I be risking accelerated corrosion by running current through my (steel) frame?

Thoughts?

- Dan