821663 Mercury ALTERNATOR

Grounding Practices
Proper grounding for the electrical system is necessary for proper engine performance and reliability. Improper grounding will result in unreliable electrical circuit paths and in uncontrolled electrical circuit paths.Uncontrolled engine electrical circuit paths can result in damage to the main bearings, to the crankshaft bearing journal surfaces, and to the aluminum components.Uncontrolled electrical circuit paths can cause electrical noise which may degrade performance.In order to ensure proper functioning of the electrical system, an engine-to-frame ground strap with a direct path to the battery must be used. This may be provided by the starting motor ground, by a frame to starting motor ground, or by a direct frame to engine ground. An engine-to-frame ground strap must be run from the grounding stud of the engine to the frame and to the negative battery post.
Illustration 1 g01486733
Typical example of grounding the battery and the cylinder head to the frame rail
(1) Cylinder head ground stud
(2) Optional engine ground stud
(3) Frame rail Connect the battery negative post to frame rail (3). From the frame rail, connect the ground wire to one of the following locations:
Cylinder head ground stud (1)
Optional engine ground stud connection (2)
Illustration 2 g01096929
Typical example of the alternate cylinder head to the battery ground
(1) Cylinder head ground stud
(2) Optional engine ground stud
(3) Frame rail The engine must be grounded to frame rail (3). Connect the battery negative post to one of the following locations:
Cylinder head ground stud (1)
Optional engine ground stud connection (2)The engine must have a ground wire to the battery.Ground wires or ground straps should be combined at the studs that are only for ground use.All of the ground paths must be capable of carrying any potential currents. A wire that is AWG 0 or more is recommended for the cylinder head ground strap.The engine alternator should be grounded to the battery with a wire size that is capable of managing the full charging current of the alternator.
When jump starting an engine, the instructions in the Operation and Maintenance Manual, "Starting with Jump Start Cables" should be followed in order to properly start the engine.This engine may be equipped with a 12 volt starting system or with a 24 volt starting system. Only equal voltage for boost starting should be used. The use of a welder or of a higher voltage will damage the electrical system.
The engine has several input components which are electronic. These components require an operating voltage.This engine is tolerant to common external sources of electrical noise. Electromechanical buzzers can cause disruptions in the power supply. If electromechanical buzzers are used near the system, the engine electronics should be powered directly from the battery system through a dedicated relay. The engine electronics should not be powered through a common power bus with other devices that are activated by the engine control switch (ECS).Engine Electrical System
The electrical system can have three separate circuits. The three circuits are the charging circuit, the starting circuit, and the low amperage circuit. Some of the electrical system components are used in more than one circuit.The charging circuit is in operation when the engine is running. An alternator creates electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output in order to maintain the battery at full charge.The starting circuit is in operation when the start switch is activated.The low amperage circuit and the charging circuit are connected through the ammeter. The starting circuit is not connected through the ammeter.Charging System Components
Alternator
The alternator is driven by the crankshaft pulley through a belt that is a Poly-vee type. This alternator is a three-phase self-rectifying charging unit. The regulator is part of the alternator.The alternator design has no need for slip rings or for brushes. The only part of this alternator that moves is the rotor assembly. All of the conductors that carry current are stationary. The following components are the conductors: the field winding, the stator windings, six rectifying diodes and the regulator circuit.The rotor assembly has many magnetic poles with air space between each of the opposite poles. The poles have residual magnetism that produces a small amount of magnet-like lines of force (magnetic field). This magnetic field is produced between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced in the stator windings. The alternating current is produced from the small magnetic lines of force that are created by the residual magnetism of the poles. The AC is changed into direct current (DC) when the current passes through the diodes of the rectifier bridge. Most of this current provides the battery charge and the supply for the low amperage circuit. The remainder of current is sent to the field windings. The DC current flow through the field windings (wires around an iron core) increases the strength of the magnetic lines of force. These stronger magnetic lines of force increase the amount of AC that is produced in the stator windings. The increased speed of the rotor assembly also increases the current output of the alternator and the voltage output of the alternator.The voltage regulator is a solid-state electronic switch. The voltage regulator senses the voltage of the system. The regulator then uses switches to control the current to the field windings. This controls the voltage output in order to meet the electrical demand of the system.
The alternator should never be operated without the battery in the circuit. The making or the breaking of an alternator connection with a heavy load on the circuit can cause damage to the regulator.
Illustration 3 g01486777
Typical cross section of an alternator
(4) Regulator
(5) Roller bearing
(6) Stator winding
(7) Ball bearing
(8) Rectifier bridge
(9) Field winding
(10) Rotor assembly
(11) Fan Starting System Components
Solenoid
Illustration 4 g00292316
Typical cross section of a solenoid
A solenoid is an electromagnetic switch that performs two basic functions:
The solenoi