General information about on-board electrical equipment (Mazda 121 (3))

When checking electrical equipment parts, a car enthusiast must understand what is meant by voltage, current and resistance.

Voltage is measured in volts (V), current (current) in amperes (A) and resistance in ohms (Ohm). Voltage in a car usually refers to the voltage of the battery. In this case, we are talking about a constant voltage of 12 V. The voltage of the battery depends on its charge and the ambient temperature. It can be from 10 to 13 V. In contrast, the voltage in the on-board network is created by the generator and is about 14 V at average speeds.

The concept of current is used quite rarely in automotive electrical engineering. Current strength, for example, is marked on fuses and indicates the maximum current that can flow so that the fuse does not burn out and the current circuit does not break.

Wherever current flows, electrical resistance occurs. Among other things, resistance depends on the following factors: conductor cross-section, conductor material, current magnitude, etc. If the resistance is too high, malfunctions occur. For example, the resistance of high-voltage wires should not be too high, otherwise the spark plugs will not have a strong enough spark to ignite the fuel-air mixture, and the engine will run intermittently.