I often take a 20 minute ferry ride to work. On the ferry, you cannot run your engine. During the hot summer days, or cold winter days, the cabin would get uncomfortably hot or cold in my ICE. This is one reason why I like the Model S...I can keep the cabin comfy even with the "engine" off. If I'm parked and have the air conditioning running, is the A/C fed from the 12V battery or the main pack? I would assume the main pack, but want to make sure. It would be a pain (not to mention embarrasing) to reach the end of the ferry only to find my car won't start, blocking traffic behind me. Much more, jumping it would be interesting as the manual has no instructions for it...Nor instructions for removing the nose cone... So the question is: what is the power source for everything in the Model S? My assumption is: -Climate control power is fed by the main pack. -Stereo, interior lights, headlights, taillights are fed directly by the 12V battery -Computers/touchscreen are fed by the pack. But who knows? Any ideas? Since as I understand it the 12V battery is slowly charged by the main pack (let's just call it a trickle charge for lack of a better term), if the accessories that are fed by the 12V battery exceed the recharge rate of the 12V battery for a certain amount of time, you'll kill the 12V and your car will not start.