Mercury 200 OptiMax Jet Drive, Service Manual, Page: 123 / 391

Charging and Starting System
Page 2B-12 90-8M0050731 MAY 2011
Flywheel Puller 91‑849154T 1
8. Remove the flywheel and inspect the flywheel for cracks or damage.
Installation
IMPORTANT: Clean the flywheel/crankshaft taper with a mild solvent and assemble dry.
1. Align the flywheel with the master crankshaft spline and install the flywheel.
2. Install the washer and nut.
3. Hold the flywheel with the flywheel holding tool and tighten the flywheel nut to the specified torque.
a - Flywheel holder
Description Nm lb‑in. lb‑ft
Flywheel nut 170 125
Flywheel Holding Tool 91‑ 52344
4. Install the alternator belt.
Alternator System
Alternator Description
The alternator employs a rotor that is supported in two end frames by ball bearings, and is driven at 2.8 times engine speed. The
rotor contains a field winding enclosed between two multiple‑finger pole pieces. The ends of the field winding are connected to
two brushes which make continuous sliding contact with the slip rings. The current (flowing through the field winding) creates a
magnetic field that causes the adjacent fingers of the pole pieces to become alternate north and south magnetic poles.
The 3‑phase stator is mounted directly over the rotor pole pieces and between the two end frames. It consists of three windings
wound 120 degrees electrically out of phase on the inside of a laminated core.
The rectifier bridge contains six diodes which allows current to flow from the ground, through the stator, and to the output terminal,
but not in the opposite direction.
When current is supplied to the rotor field winding and the rotor is turned, the movement of the magnetic fields created induces
an alternating current into the stator windings. The rectifier bridge changes this alternating current to direct current which appears
at the output terminal. The diode trio is connected to the stator windings to supply current to the regulator and the rotor field during
operation.
Voltage output of the alternator is controlled by a transistorized voltage regulator that senses the voltage at the battery, and
regulates the field current to maintain alternator voltage for properly charging the battery. Current output of the alternator does
not require regulation, as maximum current output is self‑limited by the design of the alternator. As long as the voltage is regulated
within the prescribed limits, the alternator cannot produce excessive current. A cutout relay in the voltage regulator also is not
required, as the rectifier diodes prevent the battery from discharging back through the stator.
A small amount of current is supplied by the excitation circuit in the regulator to the rotor field to initially start the alternator charging.
Once the alternator begins to produce output, field current is supplied solely by the diode trio.
The alternator is equipped with two fans which induce air flow through the alternator to remove heat created by the rectifier and
stator.
a
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