Charging System: Description and Operation

Circuit Description

The generator produces AC voltage in its windings as it is belt-driven by the engine. The rectifier converts this A/C voltage into DC voltage.
The voltage regulator, a device built-in to the generator frame, controls the generator's output to meet electrical system requirements, and also controls the charge warning lamp. Fuse 2 supplies battery voltage to the charge warning indicator. With the engine not running and the ignition switch in ON, terminal L of the regulator is grounded internally and the indicator lights up.

A small amount of current provided by both the charge warning lamp and the pre-excitation resistor is used to "excite" the magnetic field windings to start the charging process. With the engine running and the generator charging, terminal L voltage rises and the indicator goes out. If the generator fails to charge, terminal L remains below battery voltage and the indicator remains lit.