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ELECTRIC VEHICLE TECHNOLOGY BATTERIES. PREPARED BY V .BH A R A N IGH A , A P / E E E. Highest cost, weight and volume A battery consists of two or more electric cells joined Together The cells convert chemical energy to electrical energy
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ELECTRIC VEHICLE TECHNOLOGYBATTERIES PREPARED BY V.BHARANIGHA,AP/EEE Department of EEE/BSA CRESCENT IS & T
Highest cost, weight andvolume • A battery consists of two or more electric cells joined Together • The cells convert chemical energy to electricalenergy • The cells consist of positive and negative electrodes joined by anelectrolyte • It is the chemicalreaction between the electrodes • and the electrolyte whichgeneratesDC electricity • the chemical reaction can be reversed by reversing the current and the battery returned to a chargedstate BATTERIES Department of EEE/BSA CRESCENT IS & T
Non-rechargeable(primarycells) • Alkaline • Carbon-Zinc • Rechargeable(secondarycells) • Ni-Cd(Nickel-Cadmium) • Ni-MH (Nickel-MetalHydride) • Lithium-ion • Lead-Acid • Flooded – wetcells • Gel – VRLA(ValveRegulated) • AGM -VRLA Department of EEE/BSA CRESCENT IS & T
TYPES OFBATTERY • lead acid • nickeliron • nickel • Cadmium • nickel metal hydride • lithium polymer andlithium iron • sodium sulphur • sodium metal chlori • mechanically refuelled - aluminium-air andzinc-air Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER CELL AND BATTERYVOLTAGES • when the cell is delivering electricalpower, electric • cells offer nominalvoltages • Cells connected in series to give the overall voltage required • Traction batteries – 6 Vor 12 V • When a current is given out, the voltage willfall • Whenbatteryisbeingcharged,thevoltagewillrise Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER CELL AND BATTERYVOLTAGES E - open circuit Voltage isconstant But varies with State of Charge & Temperature R –low Simple equivalent circuit model of a battery - composed of sixcells Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER CHARGE (OR AMPHOUR)CAPACITY • electriccharge-mostcrucialparameter • Coulomb:thechargewhenoneAmpflowsforonesecond • (AmpereHour)Amphour:thechargewhenoneAmpflows forone • Hour • Example:10Amphours 1Ampfor10hours 2Ampsfor5hours • intheory10Ampsfor1hourbutlessthan1hour • practically Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER CHARGE (OR AMPHOUR)CAPACITY • The capacity of the large batteries used in electric vehicles ( traction batteries ) is usually quoted for a 5 hourdischarge • a battery has a capacity of 42Amphours, • C10 = 42Amphours • Battery users: • ‘a discharge current of 2C’ or 2C10 = 84Amps • ‘charging the battery at 0.4C’ = 16.8Amps Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER CHARGE (OR AMPHOUR)CAPACITY Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER CHARGE (OR AMPHOUR)CAPACITY Express the current 21 Amps from our example 42 Amphour battery, in Cnotation. Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER CHARGE (OR AMPHOUR)CAPACITY Express the current 21 Amps from our example 42 Amphour battery, in Cnotation. As a ratio of 42 Amps, 21 is 1/2 or0.5. Thus thecurrent 21 Amps =0.5C10. Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER ENERGY STORAGECAPACITY • Thepurposeofthebatteryistostoreenergy • depends on its voltage and the charge stored • SI unit is the Joule(small unit), Watthour(1 Watt for 1 hour)instead • 1 Watthour = 3600Joules • If the current is increased, both V and Creduces • Energy stored reduces if energy is releasedquickly • Depends on discharge rate andtemperature Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER SPECIFICENERGY • the amount of electrical energy stored forevery • kilogram of batterymass • Specific energy -unit: Wh/Kg • Firstapproximationofthebatterymass(inKg)canbe • found if the energy storage capacity( Wh) isknown • Specific power-unit :W/kg Department of EEE/BSA CRESCENT IS & T
RAGONEPLOT Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER SPECIFICENERGY Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER ENERGYDENSITY • It is alsoanimportant parameter • The amountofelectrical energy storedpercubic metre • ofbattery volume • Unit :Wh/m3 • Battery Volume (in m3) can be found if the energy storage capacity(Wh) isknown • Ifaknownvolumeisavailableforbatteries,thevolume (m3) canbemultiplied by thebatteriesenergy density (Wh.m−3) togive afirst approximation of how much electrical energy canbemade available Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER SPECIFICPOWER • Amount ofpower obtained perkilogram of battery • Givesinefficient operation :batteries do havea • maximumpower,itisnotsensibletooperatethemat anywhere near this maximum fewseconds Unit isWkg−1 power for more thana • verygoodspecificenergy,buthavelowspecificpower [store a lotofenergy, but can only give it out slowly] ie.,drive thevehicle veryslowly over a longdistance • thepoint thatasimple single numberanswer Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER AMPHOUR (CHARGE)EFFICIENCY • its charging efficiency is less than100% • Depends upon different types of battery, • temperature, rate of charge and state ofcharge • when going from about 20% to 80% charged the efficiency will usually be very close to 100%, but as the Batteries last 20% of the charge is put in the efficiency falls offgreatly Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER ENERGYEFFICIENCY • Energy efficiency= • electrical energy supplied by abattery • amountofelectricalenergyrequiredtoreturnittothe • state beforedischarge • reduction of overall emissions gives high energy efficiency • battery is charged anddischargedrapidly -energy • efficiency decreasesconsiderably Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER SELF-DISCHARGERATES • Self discharge : when left unused – battery discharges • higher temperatures greatly increaseself -discharge Department of EEE/BSA CRESCENT IS & T
BATTERYPARAMETER BATTERYGEOMETRY • round, rectangular, prismatic orhexagonal • Fixed variation or widervariationin Ht,Wt &L Department of EEE/BSA CRESCENT IS & T
BATTERY PARAMETERBATTERY TEMPERATURE, HEATING AND COOLING NEEDS • ambienttemperature • highertemperatures • need heating to start with and then cooling when in use • battery performance drops off at lowtemperatures • Overcomedby heating thebattery Department of EEE/BSA CRESCENT IS & T
BATTERY PARAMETERBATTERY LIFE AND NUMBER OF DEEPCYCLES • a few hundred deep cycles to 20% of the battery charge • dependsonthebatterytypeandhowitisused • Decides the lifetime of the battery which in turn reflects in electric vehicle runningcosts Department of EEE/BSA CRESCENT IS & T
Lead AcidBatteries • commonly used rechargeablebattery • Components • Lead,sulphuric acid, a plastic container • Advantages • lessexpensive • Reliableperformance • comparatively high voltage of about 2V percell • Low internalresistance Department of EEE/BSA CRESCENT IS & T
robust lead acid batteries that withstand deep cycling and use a gel rather than a liquid electrolyte areused • Expensive • Activematerial • Negative plates – spongy leadPb • Positiveplates–LeaddioxidePbO2 • Electrolyte–dilutesulphuricacidH2SO4 • Pb+PbO2+2H2SO4←→2PbSO4+2H2O • LeadSulphate +Water Department of EEE/BSA CRESCENT IS & T
capacity of a cell is approximately proportionalto • the area of theplates • internal resistance is approximately inversely proportional to the capacity & platearea Department of EEE/BSA CRESCENT IS & T
The lead and lead dioxide are not stable in sulphuric acid,and decompose, albeit veryslowly SELFDISCHARGING water is lost and turned into hydrogen and Oxygen this gas was vented out andlost Electrolyte had to be topped up from time to time withwater. modern sealedbatteries The gases are trapped in the battery, and allowed torecombine (which happens at a reasonable rate spontaneously) to reformas Department of EEE/BSA CRESCENT IS & T
Emergency lighting and alarms Conventionalcar • starting, lighting and ignition (SLI)Battery • unsuitable for electric vehicleapplications • EV • ‘traction’ • or ‘deep cycling’type • most expensive type of lead acidbattery. USAGE Department of EEE/BSA CRESCENT IS & T
REFERENCE 1) James Larminie and John Lowry, “Electric Vehicle Technology Explained”,John Wiley & Sons Ltd, 2nd edition, 2015. Department of EEE/BSA CRESCENT IS & T