Electrical Equipment System — General Information (BMW 5 Series E39)

When checking the electrical system, a car enthusiast always encounters such concepts as voltage, current and resistance in technical documents.

Voltage is measured in volts (V), current in amperes (A) and resistance in ohms (Ω). Voltage in a car usually refers to the battery voltage. This is a constant voltage of approximately 12 volts. The voltage value depends on the battery charge and the ambient temperature and can range from 10 to 13 volts. On-board voltage, on the other hand, is created by the generator and at an average engine crankshaft speed, this voltage is approximately 14 volts.

The concept of "current strength" is relatively rare in the field of automotive electrical engineering. The current strength value is indicated, for example, on fuses, and this value corresponds to the maximum current in the electrical circuit at which the fuse does not burn out and the target is not de-energized.

When flowing through an electrical circuit, the current must overcome resistance. Resistance depends, among other things, on factors such as the cross-section and material of the conductor, the value of the current consumed, etc. If the resistance is too high, faults occur in the electrical system. For example, the resistance of high-voltage wires should not be too high, otherwise it is impossible to obtain a sufficiently strong electric spark that ignites the fuel-air mixture and thus creates the prerequisites for the car engine to operate.