Very cute puzzle game! I might have missed something, but the number of moves the robots have relative to the number of power cells they have doesn't seem to be consistent across levels. In most levels, they seem to move exactly the number of cells shown on the batteries, but in level five, for instance, they seem to always move the maximum distance. And I'm guessing this is a feature rather than a bug, but I found it rather confusing.
All the same, I enjoyed it enough to stick it out, and with some trial-and-error, I ultimately finished the game. Nice work!