As another poster has said, the NexStar 11 GPS could be operated with a dead battery, but would be a real pain since all of the fine adjustments would have to be performed by bumping or tapping the scope... not a very accurate way to fine adjust the position.

I use one of the widely available auto jump start batteries to power the scope. These are usually gel cells encased in a handy plastic case with cigarette lighter outlet(s). I use one of these to power the telescope, and three Kendrick strip heaters (corrector plate, finder scope, and eyepiece) and only had battery problems after a long night with the heaters turned up high.