Drove Prime to destination, then turned off car, then to accessory to play radio. No problem until I wanted to start car. Message said 12V battery low. Could not do anything to drive. Somebody jumpered battery and car came to life. Was surprised how quickly 12V died because battery was original equipment (little over 4 years old). No warnings previously or any symptoms. Thank goodness I wasn't stranded in middle of nowhere and my dealer was just up the road ($227 poorer) I did go to a battery shop but was told they were not allowed to replace 12V in Prime because a Toyota dealer has to re-initialize the car for new battery(????) Sounded like BS. So now I am slowly re-initializing the GPS mapping (country, state cities) getting the map to point up in direction traveled not "sideways", getting the eco power curve back, setting clocks etc etc.