How to run diagnostics and remove the cause of trouble of an alternator

Each car is equipped with a variety of electronic devices. For their power supply, it is necessary to make the onboard network. An alternator is responsible for that, then the information below is about it.

An alternator operates in a team with a battery charging it, and powering the onboard network while the engine is running, converting the energy of the engine into electrical energy.

In order to understand better the operating principle of the alternator, we suggest you meet with its configuration:

№ 1– pulley

№ 2 – metal washer;

№ 3 – front end cover;

№ 4 – spacer ring;

№ 5 – rotor;

№ 6 – stator;

№ 7 – rear cover;

№ 8 – cover plate;

№ 9 – rectifier block with condenser;

№ 10 – voltage-regulated brush cap.

Let’s make a point about alternator operation:

When you turn the key in the ignition lock, a current pass through the brushes and slip rings to the field winding. There is a magnetic field in the field winding. The rotary moment is transmitted to the rotor that comes from the motor crankshaft. A magnetic field has an effect on the stator winding; an alternating voltage forms on the stator winding contacts. At the rated rotor speed, the alternator starts to operate in self-excitation mode.

The alternating voltage from the stator winding is converted by a diode bridge of the alternator into a constant one.

At the alternator diagnostic, it is necessary to pay attention to 2 key parameters:

1. Turns: when the alternator starts to work and generates a rated voltage. The rated voltage for the 12V alternator is approximately 14.5V.

2. The current transferred to the load at maximum speed. It is approximately 3000 rpm of the crankshaft.

Possible failures:

• turn-to-turnexcitation winding fault;
• turn-to-turn stator winding fault;
• short circuit of one phase on the body;
• voltage regulator failures;
• diode bridge failures.

The value of the variable component more than 10% of the load current shows that there is a certain fault in the alternator.