ALTERNATORDual Circuit5 Amp AC - 3 Amp DC - Rectifier Plug TypeThe dual circuit alternator is designed to operate as anintegral part of the engine and is separate from theengine starting system. Recommended battery sizesrange from 20 ampere hour for warm temperatureservice to 40 ampere hour in coldest service.Fig. 166 - Dual Circuit AlternatorThe dual circuit alternator is actually two separatealternator systems. A single ring of magnets inside theflywheel supplies the magnetic field for both of them.One alternator system uses a solid state rectifier andprovides battery charging current. The other alternatorsystem feeds alternating current directly to the lights.Since the two are electrically independent, use of thelights does not reduce the charge going into the battery.Fig. 167 - Typical Wiring DiagramThe battery is not used for the lights, so lights areavailable even if the battery is disconnected or removed.The alternator uses less than 0.2 horsepower.Current for the lights is available as long as the engine isrunning. The output depends upon engine speed.Twelve-volt lights with a total rating of 60 to 100 wattsmay be used. With lights rated at 70 watts, the voltagerises from 8 volts at 2400 RPM to 12 volts at 3600 RPM,so the brightness of the light changes with the enginespeed.The current from the battery charging alternator isunregulated and is rated at 3 amperes. The output risesfrom 2 amperes at 2400 RPM to 3 amperes at 3600RPM.There is one external connection. The battery chargingcurrent connection is made through one terminal of a twoconnector plug. Current for lights is available at thesecond terminal of this plug. The plug is polarized toprevent improper connections. The return circuit for bothalternators is through ground to the engine block.CHECKING BATTERY INSTALLATIONCheck if battery polarity is correct. Negative (-) side ofbattery should be grounded to engine or frame; positive(+) side of battery to alternator output lead. Figure 167.WHEN CHECKING ALTERNATOR COMPONENTS,MAKE THE TESTS IN THE FOLLOWING SEQUENCE:TESTING ALTERNATOR CHARGING (DC) OUTPUTSet #19236 VOA meter to measure amperes. Attachleads in series with positive battery terminal and wire asshown in Fig. 168. Meter should indicate output. Thecharge range is dependent on the condition of the batteryand engine speed. If meter shows no charge or shows adischarge, test diode and stator.Fig. 168 - Testing Alternator DC Output52
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