A few days ago, whilst camping, I had the misfortune to encounter a flat battery situation. Now, it doesn't matter if there is charge left in the main 'driving' battery that forms part of the hybrid motive power plant, if the 12V starting battery is dead then the car will not start. I think this happened due to a combination of starting the car without depressing the brake pedal, blowing up two air beds plus letting the wee ones clamber in and out of the car without shutting doors, leaving the courtesy lights on. After a quick slap of hand to forehead and raising eyes to heaven, I consulted the owner's manual. The jump starting instructions begin on page 362 (my UK Owners Manual) but perhaps this may be different on your Prius manual. Regardless, the instructions in the owner's manual were useless to me because I didn't have any jump start leads. I now do. I recovered the situation by phoning my breakdown company. A local garage truck shortly came out and sorted the problem within two minutes. I took the car for a 20 minute drive afterwards just to ensure there was plenty of charge in the small 12V battery.
Having had this experience, I though I should blog about it. There are various videos on YouTube that show you the procedure. Here is one such video that is pertinent to the second generation Prius. Enjoy!
Jump Starting Your Prius for the Mechanically Challenged.mov - YouTube
The Diary of a Toyota Prius: How to Jump Start your Prius