Why can’t a battery-based car just use a step down to 12 volts instead of a separate 12 volt car battery?

Question

Why can’t a battery-based car just use a step down to 12 volts instead of a separate 12 volt car battery?

In: 10

Answer 1

I gonna throw an educated guesstimation, you see, the main battery of the car works isolated from all the other systems of the car since is relatively high voltage, whenever the you turn off the car the battery gets f
Physically disconnected by a device called contactor, this apparently helps with the battery life and safety, what controls this device is the low voltage circuit of the car, so in order to start your electric car you still need a 12v battery

TLDR; you need a 12v battery for controlling the high voltage circuits