Internal and External Earth of Starter Motors

To understand the internal and external earth of the starter, you must understand what the earth is first. The earth is a term of circuit, most commonly seen in the auto repair industry.

The path that current flows through is called circuit. The current starts from the positive pole and pass through the entire circuit, of course, there must be resistance in the circuit or there will be a short circuit. After the current passes through all the electrical appliances and back to the negative pole that’s a formed closed loop.

There are also positive pole and negative pole on the battery of the car. The current flows from the positive pole of the battery and pass all the appliances on the car to the negative pole which formed a closed loop to supply the electricity to all the electrical appliances, so that all the appliances on the car can work properly. And because the body of the car is made of metal which has electrical conductibility so when people design the car they usually use the body of the car as the negative pole to connect with the negative pole of the battery.

The internal earth of the starter means the armature of the starter is directly connected with the housing. Because the housing is installed on the frame of the car, the current directly flows through the frame and back to the negative pole of the battery to form a closed loop. The external earth is the armature of the starter insulates from the housing, it needs a terminal to connect the negative pole of the battery to form a closed loop.

Tips from: Shuocun Zhou