Stacking Star Trails: Tips & Techniques

Found this great article by Harold Davis on how to create star trail photos.
http://blogs.oreilly.com/digitalmedia/2008/11/stacking-star-trails-tips-tech.html

I tried a few last year during the Perseids metor shower with varying results. (Didn't happen to capture any metors either.)
I found that the long exposures drained my battery incredibly quickly. I will probably head out to the salt flats or the sand dunes this weekend to try this out.