I am usually right around home when I finally hit 30%, and I land when I get the low battery warning. The lowest my batteries have been is 28%.
I would like to try getting to 10% just to see how the AC behaves when forced landing. I could put it 40 or 50 feet in the air and try it.
I did read on here somewhere that the batteries don't like being discharged too much however, and being that everything is still new, I'm trying to be 'nice' to it still...