ALTERNATORDual Circuit - Fuse TypeDual Circuit Alternator with FuseThis efficient gear drive, 12 volt battery powered startersystem is compact and powerful. It is available witheither a rope or rewind auxiliary starter. Recommendedbattery sizes range from 20 ampere hour for warmtemperature service to 40 ampere hour in coldestservice.Fig. 175 - Alternator AssemblyDUAL CIRCUIT ALTERNATORThe dual circuit alternator is actually two separatealternator systems. A single ring of magnets inside theflywheel supplies the mag-netic 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 inde-pendent, use of thelights does not reduce the charge going into the battery.Fig. 176 - Typical Wiring InstallationThe battery is not used for the lights, so lights areavailable even if the battery is disconnected or removed.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 are two external connections. The batterycharging current connection is made through a 7.5ampere fuse mounted in a fuse holder beside the startermotor. Current for the lights is available at a plasticconnector located below the fuse-holder. The twoconnections are differ-ent so they cannot be accidentallyinterchanged. The fuse protects the 3 amp chargingalternator and rectifier from burnout due to improper(reverse polarity) battery connections. The 5 amplighting alternator does not require a fuse as a shortcircuit in its output will not damage it. The return circuitfor both alternators is through ground to the engineblock. The alternator uses less than 0.2 horsepower.CHECKING DUAL CIRCUIT ALTERNATORFuse BlownCheck if battery polarity is correct: Negative (-) side ofbattery should be grounded to engine or frame; positive(+) side of battery to (fused) alternator output lead.Figure 177. If reversed, correct and put in new fuse.WHEN CHECKING ALTERNATOR COMPONENTS,MAKE THE TESTS IN THE FOLLOWING SEQUENCE:BATTERY RUNS DOWNTesting Alternator Charging OutputInstall ammeter in series with charging lead, as in Figure177. Start engine. Ammeter should indicate charge.The charge rate is dependent upon the condition of thebattery.55
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