Positive earth systems were used in earlier vehicles, and in this type of system, the positive terminal of the battery is connected to the chassis of the vehicle. This means that the chassis is at a positive potential, and all other electrical components are connected to the chassis and are therefore also at a positive potential. The negative terminal of the battery is connected to the starter motor, which is the only component that is not at a positive potential.
Negative earth systems are used in most modern vehicles, and in this type of system, the negative terminal of the battery is connected to the chassis of the vehicle. This means that the chassis is at a negative potential, and all other electrical components are connected to the chassis and are therefore also at a negative potential. The positive terminal of the battery is connected to the starter motor, which is the only component that is not at a negative potential.
The main advantage of a negative earth system over a positive earth system is that it is less prone to corrosion. In a positive earth system, the positive terminal of the battery is connected to the chassis, which is exposed to the elements. This can cause the terminal to corrode, which can lead to electrical problems. In a negative earth system, the negative terminal of the battery is connected to the chassis, which is not exposed to the elements. This means that the terminal is less likely to corrode, which reduces the risk of electrical problems.
Negative earth systems are also more efficient than positive earth systems. In a positive earth system, the current has to flow through the chassis of the vehicle in order to reach the electrical components. This can cause a voltage drop, which can reduce the efficiency of the electrical system. In a negative earth system, the current does not have to flow through the chassis, which eliminates the voltage drop and increases the efficiency of the electrical system.
For these reasons, negative earth systems are used in most modern vehicles.
