Yes, I was planning on wiring a heavy-duty socket with large-gauge wire directly to the battery - I should be able to figure out what kind of fuse to put in-line to protect the system while allowing sufficient current flow with some simple math.
Right now the most powerful 12V ballast I've found is only 50W, and I'd like to do at least 100W. It would be annoying but I might be doomed to wiring in a power-inverter and using an AC ballast. A 3000K or 4000K bulb pushing 7000 lumens for 100W over 11000 lumens for 150W wouldn't be that expensive either... or at least those are the specs claimed on bulbs.com
These
guys have a 70 watt ballast. It's designed to operate a double-ended bulb but it should work fine with a D2 bulb. Drop 'em a line and see.
I'm beginning to think that I would be able to light my whole apartment with one or two HID fixtures and use the same amount of energy as CFLs...
CFLs still have the edge in efficiency, they just can't compete with HIDs or LEDs for surface brightness.
You could light your apartment with HIDs but the result would not be pleasant. Conventional long-arc HIDs are significantly more efficient than the short arc versions. Efficiency is one of those things that is sacrificed to get a small arc size and high emission.
You can buy a 175 watt HID lamp in an envelope about the size of a 100 watt light bulb at Home Depot for less than $20. A 175 watt mercury vapor security light ballast will usually strike that lamp. If not, add a few more turns to the ballast. Less than $50 if you shop carefully.
I built a "trouble light" (drop light) around that configuration, with the ballast in a small metal box. It works great, produces massive light for its size and doesn't make too much heat.
The problem you'll run into in trying to satisfactorily light your apartment, for example, is that the relatively point-source of light is harsh and produces lots of glare and sharp shadows. It's still much more pleasing to light with diffuse light from several luminairies or tubular sources such as neon tubes using "incandescent" phosphor.
John
