I can't comprehend why new cars are having electrical stuff especially BRAKES and STEERING. What the forget happens if your battery dies or some stuff while on the road? You're going to kill yourself or someone else. What kind of dumbass thought of that?
As long as the engine is on and fueled, there's no way you'll run out of battery. The engine produces more power than what the car consumes. That's why, if you have a dead battery, you need jumper cables to start it and it will run smoothly until you turn it off.
But of course, if you have the AC on, a minifridge (via those DC-to-AC converters), and while watching Breaking Bad via the tv (assuming the car has one), there's a higher chance of your car turning off midroad. If you're driving a manual, hold the clutch and drive until the road's friction slows it to a stop. If you're driving an automatic, I have no idea what you'd do if this were to happen.