The Karma manual indicates that the battery indicator will start flashing when the battery is at 20% capacity.

At least on my unit (1.11 firmware) the battery gauge will go down to what looks like very near empty, and then it will start flashing. At the risk of asking a dumb question, does this mean that even what looks like "empty" on the gauge means that there's still 20% juice left?

I'm definitely not complaining: I played 160kbps OGG files for nearly 9 hours before the gauge started flashing. Doing the math, especially if 20% was still left, then that is great battery life for that high a bit-rate file...