I just read interesting story about a guy who run down his 12V battery in Prius and then tried to jump it. To make long story short , it seems he reversed polarity and caused close to $6000 in damage which Toyota doesn't want to cover under warranty due to his fault of hooking up cables wrong, which he isn't even sure he did. Well, since our car is very similar to Prius I would advise anybody who has flat battery to be very, very careful with boosting the battery, since the inverter is right there and it's very expensive piece that could be easily damaged with reversed polarity (I even had brand new jump cables that were reversed with red clamp one side and black on the other of the same wire and it took me a while to figure it out why sparks were flying everywhere even after triple checking for proper connection). For the same reason I would suggest not to give boost to other people's car's either. The good news is our car doesn't need much, just to boot up computer, so probably even 12 v AA cell pack would be good enough to start it and using long, thin wires , not capable of large amperage hooked up to cigarette lighter should be safer, than jump cable with 600 amp capability directly to battery post.