1997 Lexus ES300 Charging System Circuit Diagram. The charging system circuit consist of: ignition switch, fusible link block, charge warning light, junction connector, IC regulator, generator, and battery. The electrical system is a 12 volt system to run all the electronics on the vehicle and to keep the battery charged. The voltage regulator controls the voltage generated by the alternator at the appropriate level. The relay is used to control the flow of current between generator and battery. It acts as circuit breaker.