Our chassis weighs 14 pounds, WITH the battery.

On a more serious note, 15/120 isn't much, but it's a pretty decent amount of the robot weight. It's like a whole apparatus. It seems like the battery can quickly change the center of gravity on a robot depending on where it is. Unfortunately, our center is hollowed out to take balls in, so it looks like we'll either have to find a new place for our battery, or put it on top of our shooter, which probably won't work very well.