On XP11, it appears that ground services aren't always available. As soon as cold-and-dark sim starts, the 737 starts slowly rolling. The location doesn't have external power available, and I don't want to start the APU yet. I turn the battery on, and the electric hyd pumps don't start, so I assume they need AC power? At any rate, I establish AC using standby power ON, and the elec hydro pumps still don't work, so perhaps they don't run off the standby bus? What busses are they powered from and how can I prevent my plane from rolling?