Consumers are connected to a positive power source by a wire, and to a negative one - through the car body (mass). This method reduces the number of wires and simplifies installation.
Cars are fitted with low-maintenance or maintenance-free batteries.
The electrical system has a twelve-volt negative ground supply and consists of a battery, a generator, a starter, electrical consumers and electrical circuits.
The battery is charged by a generator, which is driven by a belt from the crankshaft pulley.
The starter is a mixed-excitation DC electric motor with an electromagnetic traction relay. When the engine is started, the traction relay moves the pinion gear into engagement with the flywheel ring gear before the starter is powered by the battery. After starting the engine, the freewheel disengages the starter armature from the flywheel ring gear.
Precautions
When working on the electrical system, so as not to damage semiconductor devices (diodes and transistors) the following requirements must be met:
- while the engine is running, do not disconnect the battery, alternator or any electrical connectors;
- when carrying out any work, remove the negative terminal from the battery;
- when carrying out electric welding work on a car, turn off the alternator and electronic control device;
- do not allow the engine to run with the generator disconnected from the electrical system;
- do not test the generator for operation by shorting its output contacts to ground.