Unit 12 Automobile Power Supply System

Chaper5ElectricalEquipmentUnit12AutomobilePowerSupplySystemNewWordsandExpressionselectrostaticadj.静电的,静电学的batteryn.电池；蓄电池storagen.贮藏(量),贮藏库,存储galvanicadj.流电的,抽搐的,以流电所产的，触电似的reverseadj.相反的；反向的；n．相反，反面electrolyten.电解质；电解液sulfuricadj.[化]硫磺的,含多量硫磺的corrosiven.腐蚀物(剂)；adj.腐蚀的；侵蚀性的thoroughlyadv.十分地,彻底地acidn.[化]酸,俚迷幻药gogglen.眼睛睁视,(复数)风镜,护目镜sealedadj.未知的,密封的bafflevt.困惑,阻碍,为难NewWordsandExpressionsraten.比例，率；比率anoden.[电]阳极,正极terminaln．末端；终点电极，接头accessoryn．附件；a．附属的；辅助的wipern．抹布；(汽车挡风玻璃的)雨刷standpointn．立场，观点porousadj.多孔渗水的bulkyadj.体积大的，庞大的；笨重的CCA(ColdCrankingAmps)冷启动电流安培值sulfuricacid硫酸beflushedwith冲洗AutomotiveBatteryTheautomotivebattery,inscienceandtechnology,isadevicethatstoresenergyandmakesitavailableinanelectricalform.Althoughsuchstorageinanelectrostaticformispracticalinsomespecializeduses,batteriesusuallyconsistofelectrochemicaldevicessuchasoneormoregalvaniccellsormorerecentlyfuelcells,andmanyinthefutureuseothertechnologies.Inanautomotivebatterywecanreversetheelectrochemicalaction.Thepurposeofthebatteryistosupplycurrenttothestartermotor,providecurrenttotheignitionsystemwhilecranking,tosupplyadditionalcurrentwhenthedemandishigherthanthealternatorcansupplyandtoactasanelectricalreservoir.Mostcarbatteriesarelead-acidbatteries.Theleadacidbatteryismadeupofplates,lead,andleadoxidewitha35%sulfuricand65%watersolution.Thissolutioniscalledelectrolytewhichcausesachemicalthatproduceelectrons.Theautomotivebatteryrequiresspecialhandling.Theelectrolyteinsidethebatteryisamixtureofsulfuricacidandwater.Sulfuricacidisverycorrosive;ifitgetsonyourskinitshouldbeflushedwithwaterimmediately;ifitgetsinyoureyes,youshouldimmediatelyflushthemthoroughlywithwaterandseeadoctorrightaway.Inthissituation,timeiscritical.Remember:itismoreimportanttoflushimmediately.Donottakethetimetomakeupasolutionfirst.Sulfuricacidwilleatthroughclothing,soitisadvisabletowearoldclothingwhenhandlingbatteries.Itisalsoadvisabletoweargogglesandgloveswhileservicingthebattery.Whencharging,thebatterywillemithydrogengas;itisthereforeextremelyimportanttokeepflamesandsparksawayfromthebattery.Becausebatteriesemithydrogengaswhilecharging,thebatterycasecannotbecompletelysealed.Today'sbatterieshavesmallventsonthesideofthebattery;thegasesemittedhavetogothroughbafflestoescape.Today'sbatteriesareratedincoldcrankingamps.Thisrepresentsthecurrentthatthebatterycanproducefor30secondsat0degreesbeforethebatteryvoltagedropsbelow7.2volts.AnaveragebatterytodaywillhaveaCCA(ColdCrankingAmps)of500.Withthemanydifferentmakesandmodelsofcarsavailabletoday,batterieswillcomeinmanydifferentsizes,butallsizescomeinmanyCCAs.AccessoryBatteryJustaboutanyelectriccarhasoneotherbatteryonboard.Thisisthenormal12-vohlead-acidbatterythateverycarhas.The12-voltbatteryprovidespowerforaccessoriesthingslikeheadlights,radios,fans,computers,airbags,wipers,powerwindowsandinstrumentsinsidethecar.Sinceallofthesedevicesarereadilyavailableandstandardizedat12volts,itmakessensefromaneconomicstandpointforanelectriccartousethem.Whenyouplacethekeyinyourcar'signitionandturntheignitionswitchtoON,asignalissenttothecar'sbattery.Uponreceivingthissignal,thecarbatterytakesenergythatithasbeenstoringinchemicalformandreleasesitaselectricity.Thiselectricalpowerisusedtocranktheengine.Thebatteryalsoreleasesenergytopowerthecar'slightsandotheraccessories.Thestandardautomotivebatteryintoday'svehiclesis12volts.Eachbatteryhassixcellswith2.1volts.Acarbatteryisconsideredfullychargedat12.6volts.Whenabatterydropsvoltage,evenasmallamount,itmakesabigdifference.Forinstance,whenabatterydropsfrom12.6to12.0volts,itspowerdropsfrom100%to25%.At12.4volts,acarbatteryis75%charged.At12.2volts,it's50%charged.PartTwoReadingMaterialThechargingsystemrequiresperiodicinspectionandservice.Specificproblemsymptoms,theirpossiblecause,andtheservicerequiredarelistedinthechartbelow.Theserviceactionsrequireathoroughvisualinspection.Problemsidentifiedmustbecorrectedbeforeproceedingwithelectricaltests.Theseelectricaltestsinclude:analternatoroutputtest,chargingcircuitvoltagedroptests,avoltageregulator(non-IC)test,chargingcircuitrelay(lamp,ignition,engine)tests,andalternatorbenchtestsandsoon.DiagnosisandTestingofChargingSystemVISUALINSPECTIONAvisualinspectionshouldalwaysbeyourfirststepincheckingthechargingsystem.Anumberofproblemsthatwouldreducechargingperformancecanbeidentifiedandcorrected(SeeFig12-2)..CHECKTHEBATTERYCheckforproperelectrolytelevelandstateofcharge.Whenfullycharged,specificgravityshouldbebetween1.25and1.27at800F(26.70C).Checkthebatteryterminalsandcables.Theterminalsshouldbefreeofcorrosionandthecableconnectionstight.CHECKTHEFUSESCheckthefusesforcontinuity.TheseincludetheEnginefuse(10A),Chargefuse(7.5A),andIgnitionfuse(7.5A).INSPECTTHEDRIVEBELTCheckforbeltseparation,cracks,fraying,orglazing.Ifnecessary,replacethedrivebelt.Checkthedrivebelttensionusingthepropertensiongauge,NippondensoBTG-20.Refertotheappropriaterepairmanualforproperdrivebelttension.Newbelts(usedlessthan5minutesonarunningengine)areinstalledwithgreatertensionthanusedbelts.Ten