Electrical System

This lesson we were talking about the electrical system. The electrical system starts with the battery, we use the battery to power the starter motor and this cranks the engine, when the engine is cranked it drives the auxiliary belt which powers the alternator via a pulley on the front of the alternator. The alternator is just one big electrical generator it uses windings of wire around the outside of a rotating magnet to create an electronic charge, when the engine is running the alternator produces generally about 14V this will charge the battery as it has lost some charge from powering the starter motor. The alternator is also used to power things like the in car entertainment (radio, sat-nav, and things such as these). The way we connect all of these electrical components is through the wiring loom, the loom is all of the wires that are used in the car bound together and it all runs through the car together so we can minimise any damage and so it is easier to find should we need to trace a wire or repair/modify anything on the electrical system.

The system is made up of components such as relays, fuses, wires, ECU’s and connectors.

A relay is a low current circuit that controls a high current circuit, it is basically a low current electro magnet that is switched on to attract a magnetic switch, this will complete the circuit for the high current side and allow current to flow.

A fuse is in a system to prevent damage to components, it is a component itself that is designed to fail when there is too much voltage going through a system, this melts the wire inside the fuse and creates an open circuit and stops the current reaching the vital components in the system, this saves costs of replacing expensive components. We can also get resettable fuses which act like a trip switch in a house electrical system.

Wires are there just to connect the components and carry a voltage through the system to make it work.

The ECU is there to control actuators from incoming sensor data, it uses look up tables and can be mapped for better efficiency/performance depending on the type.

Connectors are there so we don’t have to hardwire components in the system, if we were to do this and something broke then it would be hard to replace the component as opposed to just unplugging it, connector types vary from system to system depending on how many “pins” we need for the component.