The output of the alternator produces a constant voltage, which is used to operate the vehicle's electrical system and to charge the battery. The voltage value is controlled by an electronic voltage regulator.
Voltage is supplied continuously:
- Via a 10 A fuse (No. 33, located in the power fuse box).
- To terminal 4 (S) of the generator.
The voltage from terminal B is used to charge the battery and to operate the vehicle's electrical system. The generator output voltage is controlled by an electronic voltage regulator, the input voltage value is determined at pin 4 (S).
The generator is grounded to the cylinder block.
When the ignition key is in the ON or START position, voltage is supplied to:
- Via a 10 A fuse (No. 14, located in the fuse box of the J/B mounting block).
- To the instrument panel contact No. 20 (battery charge indicator lamp).
Grounding is connected:
- To the instrument panel output #4.
- Through terminal 3 (L) of the generator.
- To the E terminal of the generator.
- Via the ground connection point on the E29 body.
When voltage and ground are connected, the battery charge indicator lamp lights up. When the generator produces sufficient voltage with the engine running, the ground circuit is opened and the battery indicator light goes out. If the battery charge indicator light comes on while the engine is running, this indicates a fault in the charging system.
The battery is the first link in the chain of mechanisms that work to power the engine. Typically, it is a lead-acid type, consisting of six batteries connected in series to produce a voltage of 12 V. Each of the six cells (cans) contains a certain number of positive and negative plates, separated by a small distance and located in an aqueous solution of sulfuric acid. The two types of plates are made of dissimilar metals. This causes a chemical reaction that produces current when the positive and negative terminals of the battery are connected to an electrical consumer—a lamp, a motor, etc. The continuous flow of electrons eventually converts the acid in the electrolyte into water, making the two plates chemically identical. As electrical energy is "removed" from the battery, its voltage drops. Thus, measuring the battery voltage and electrolyte composition makes it possible to control the battery's ability to produce voltage. When the engine is started, electrical energy is "removed" from the battery. If the battery charging circuit is in good condition and operating conditions are normal, the energy expended by the battery will be recaptured by the generator, which sends electrons back through the battery in the opposite direction to the normal flow, returning the battery to its original chemical state.
The battery and starter are connected to each other by very thick electrical wires, which helps reduce the resistance to current. The main power wire coming from the battery goes directly to the starter, while other electrical consumers are connected with thinner wires. When the starter is operating, voltage from the battery is supplied to the starter, and it is grounded through the vehicle body and the negative battery terminal wire.
The battery charging system supplies voltage for the operation of the vehicle's ignition and starting systems and electrical consumers. The battery serves as a storage facility where electricity is accumulated (in chemical form) electrical energy generated by the engine's generator. The system is also started by over-regulating the generator output voltage from battery recharging and supplying excess voltage to consumers.
The car generator is driven mechanically from the engine crankshaft by a V-belt. It contains two windings of thin wire, one stationary (the stator) and one moving (the rotor). The rotor, also known as the armature, contains a thin wire wound around an iron core mounted on a shaft. Electric current flowing through two windings (it is initially supplied by the battery) creates an intense magnetic field around both the rotor and the stator, and the interaction between the two fields produces enough voltage for the generator to power the loads and charge the battery.
The charging system includes an alternator, a voltage regulator (it's built-in, electronic type), the battery charge indicator light, the battery, the power fuse or fusible link, and the wires that connect all of these parts.
The charging system supplies power to the ignition system, lighting devices, radio, etc. The generator is driven by a drive belt.
The job of the voltage regulator is to limit the generator voltage so that it does not increase above a certain value. This prevents voltage surges, circuit overloads, etc. when the generator is under high load.
The charging system is protected by several power fuses or fusible links located in the engine compartment fuse box. If there are problems with the charging system, check the fuses and fusible links for integrity and broken contacts.
The charging system generally does not require periodic maintenance. However, the drive belt, battery, wires and their connections should be checked at the intervals specified in Chapter "Maintenance".
When connecting to the electrical circuits of a vehicle equipped with an alternator, use extreme caution and consider the following.
- When connecting the wires from the battery to the generator, do not reverse their polarity.
- Before using electric welder to repair any part of the vehicle, always disconnect the wires from the generator and from the battery.
- Never start the engine when a charger is connected to the battery.
- Always disconnect both battery cables before connecting the charger to the battery (first, disconnect the negative wire, then the positive wire).