The wire around the top of the nail must be bare where it touches the nail. Close the switch. Open the switch. You use a key and start the car by using a relay. Turning the ke y closes a switch that starts current flowing from the battery.
Electrons move through the starting circuit to an electromagnet that closes a relay.
The relay allows a large current to flow to the electric motor that starts the car. Use your own symbol for your electro-board. Use the diagram to map out the route of the electrons as they move from both batteries. Build two relays and use one to turn on the other. Build a series of relays to send a long distance signal.