There are a couple discussions dancing around the 12 volt system in Roadsters: http://www.teslamotorsclub.com/showthread.php/4849-12-volt-accessories http://www.teslamotorsclub.com/showthread.php/4560-Voluntary-fix-offered-for-Roadster-models-2-0-and-2-5?highlight=12+volt+battery However, I couldn't find a lot of specifics on the 12 volt battery. 1) Is it just an AGM battery? 2) How/when is it charged? 3) Can anyone categorically state which systems it drives and/or acts as a buffer on? 4) Has anyone had it fail? If so, what happens?