when I was first looking at my HAH, it sat on the dealer lot long enough to deplete the 12V battery. When I tried to start it, the EL gauges would dim down and flicker off. They connected a booster pack, and I was able to IMA start almost instantly. It is very dependent on the 12V system to function, my guess to enable the HV contactors to power up the system, they're just big relays, with a coil that needs to energize. Without the juice, it is as if the HV pack doesn't even exist. If only there were a way to convert some of that power from the HV pack to 12V as a "jump start," this would be a moot point. Most functions are powered from the 12V such as lighting, so this leaves a certain vulnerability similar to that of a conventional vehicle.