3 independent wirings, with little other added electronics/draw (most is stock, actually), the alternator/battery would provide plenty of juice. The main issue would be leaving them on. Plus, I don't have to run all three at once (usually only ran 1, aimed to the outside of the stock brights) unless really dark).
3 sets would be mainly cosmetic and primarily for moonless runs on rural (mountain or in the woods) roads. I am in that situation more than I would expect. My fault for living in a small rural town and driving in the mountains.
Many of my mountain AND country miles are in national or state parks =with lots of wild animals wandering around, inc. deer, bears, yotes, and even wild cats- bobcats and panthers/cougars. I've SEEN all those on roads. Hence my interest in upgraded bright-lighting. "Normal" projectors are plenty for city/town driving, but the stock brights are wanting, esp. in light spread to the sides.
My Miata has Hella H4s, which work well. The xB's brights stink in comparison. It is really noticable in late November, December, and January, with "night" coming by 5pm. In the summer, the dark-dark comes late enough that I am usually home by then (kids at home wake me up early).
DO NOT use brights in the city/town!
In ANY populated or lit situation, I don't use them (the KCs) at all- only stock lamps.