Sitting in a prius for long periods of time?

Wait for FlagMichael to respond to this. He is our Prius owner/expert.

I wouldn't worry about the small amount it takes to run the radio. In the days of tube radios half an hour might drain the battery dead. In my car if you left the radio on all night it would probably not start. If the radio on the Prius is by any chance tied to the storage battery, then the 50 watts of the radio would be nothing. The car does not have to be moving to charge, although it would charge faster at higher speeds. But if you start the car you have to weigh the loss of starting against the recharge time.

A logical and intelligent person would download a copy of the owners manual from the Toyota website and read it. Many of your questions can be answered there.

I say double check with the owners manuel just to be sure

Take a look at the radio's fuse to estimate how much it might draw. Consider what else uses that same circuit. Your stereo might dissipate 22 watts into each of 4 channels. Just don't blast the stereo while you wait and use one of those battery checkers that plugs into the lighter socket to get a read on the battery's condition.

Be sure to wear your lead shorts - we're just beginning to get the data on the health effects of sitting in the magnetic field of all those batteries !!!

Use a portable radio powered by AA size batteries. Leave the engine off.

you might ask all that at the dealer before you buy it.