DESCIPLINE : ELECTRICAL II GROUP : A SUBMITTED TO: Prof. Kashyap Gupta PREPARED BY : PATEL SMIT...

Click here to load reader

  • date post

    19-Jan-2016
  • Category

    Documents

  • view

    215
  • download

    0

Embed Size (px)

Transcript of DESCIPLINE : ELECTRICAL II GROUP : A SUBMITTED TO: Prof. Kashyap Gupta PREPARED BY : PATEL SMIT...

  • DESCIPLINE : ELECTRICAL II GROUP : ASUBMITTED TO:Prof. Kashyap Gupta

    PREPARED BY : PATEL SMIT =13ELEE105PATEL KEYUR=13ELEE103 PARMAR BHAVIN =13ELEE107VEGAD RUTUL=13ELEE101

  • OutlineWhy is this important?Brief history of batteriesBasic chemistryBattery types and characteristicsCase study: ThinkPad battery technology

  • MotivationTo exploit properties of batteries in low-power designsProtocols (Span , MAC layer)Hardware (Cricket)Example: n cells; discharge from each cell, round-robin fashion [Chiasserini and Rao, INFOCOM 2000]

  • Battery (Ancient) History1800Voltaic pile: silver zinc1836Daniell cell: copper zinc1859Plant: rechargeable lead-acid cell1868Leclanch: carbon zinc wet cell1888Gassner: carbon zinc dry cell1898Commercial flashlight, D cell1899Junger: nickel cadmium cell

  • Battery History1946Neumann: sealed NiCd1960sAlkaline, rechargeable NiCd1970sLithium, sealed lead acid1990Nickel metal hydride (NiMH)1991Lithium ion1992Rechargeable alkaline1999Lithium ion polymer

  • Battery NomenclatureDuracell batteries6v dry cell9v battery

  • The Electrochemical Cell

  • The Electrochemical Cell (2)Zinc is (much) more easily oxidized than Copper

    Maintain equilibrium electron densitiesAdd copper ions in solution to Half Cell IISalt bridge only carries negative ionsThis is the limiting factor for current flowPick a low-resistance bridge

  • The Electrochemical SeriesMost wants to reduce (gain electrons)GoldMercurySilverCopperLeadNickelCadmiumIronZincAluminumMagnesiumSodiumPotassiumLithiumMost wants to oxidize (lose electrons)

    But, theres a reason its a sodium drop

  • Battery CharacteristicsSizePhysical: button, AAA, AA, C, D, ... Energy density (watts per kg or cm3)LongevityCapacity (Ah, for drain of C/10 at 20C)Number of recharge cyclesDischarge characteristics (voltage drop)

  • Further CharacteristicsCostBehavioral factorsTemperature range (storage, operation)Self dischargeMemory effectEnvironmental factorsLeakage, gassing, toxicityShock resistance

  • Primary (Disposable) BatteriesZinc carbon (flashlights, toys)Heavy duty zinc chloride (radios, recorders)Alkaline (all of the above)Lithium (photoflash)Silver, mercury oxide (hearing aid, watches)Zinc air

  • Standard Zinc Carbon BatteriesChemistryZinc (-), manganese dioxide (+)Zinc, ammonium chloride aqueous electrolyteFeaturesInexpensive, widely availableInefficient at high current drainPoor discharge curve (sloping)Poor performance at low temperatures

  • Heavy Duty Zinc Chloride BatteriesChemistry Zinc (-), manganese dioxide (+)Zinc chloride aqueous electrolyteFeatures (compared to zinc carbon)Better resistance to leakageBetter at high current drainBetter performance at low temperature

  • Standard Alkaline BatteriesChemistry Zinc (-), manganese dioxide (+)Potassium hydroxide aqueous electrolyteFeatures 50-100% more energy than carbon zincLow self-discharge (10 year shelf life)Good for low current (< 400mA), long-life usePoor discharge curve

  • Alkaline Battery Discharge

  • Lithium Manganese DioxideChemistryLithium (-), manganese dioxide (+)Alkali metal salt in organic solvent electrolyteFeatures High energy densityLong shelf life (20 years at 70C)Capable of high rate dischargeExpensive

  • Lithium v Alkaline Discharge

  • Secondary (Rechargeable) BatteriesNickel cadmiumNickel metal hydrideAlkalineLithium ionLithium ion polymerLead acid

  • Nickel Cadmium BatteriesChemistryCadmium (-), nickel hydroxide (+)Potassium hydroxide aqueous electrolyteFeaturesRugged, long life, economicalGood high discharge rate (for power tools)Relatively low energy densityToxic

  • NiCd RechargingOver 1000 cycles (if properly maintained)Fast, simple charge (even after long storage)C/3 to 4C with temperature monitoringSelf discharge10% in first day, then 10%/moTrickle charge (C/16) will maintain chargeMemory effectOvercome by 60% discharges to 1.1V

  • NiCd Memory Effect

  • Nickel Metal Hydride BatteriesChemistryLaNi5, TiMn2, ZrMn2 (-), nickel hydroxide (+)Potassium hydroxide aqueous electrolyteFeaturesHigher energy density (40%) than NiCdNontoxicReduced life, discharge rate (0.2-0.5C)More expensive (20%) than NiCd

  • NiMH Battery Discharge

  • NiMH RechargingLess prone to memory than NiCdShallow discharge better than deepDegrades after 200-300 deep cyclesNeed regular full discharge to avoid crystalsSelf discharge 1.5-2.0 more than NiCdLonger charge time than for NiCdTo avoid overheating

  • NiMH Memory Effect

  • NiCd v NiMH Self-Discharge

  • Secondary Alkaline BatteriesFeatures50 cycles at 50% dischargeNo memory effectShallow discharge better than deeper

  • NiCd v Alkaline Discharge

  • Lead Acid BatteriesChemistryLeadSulfuric acid electrolyteFeaturesLeast expensiveDurableLow energy densityToxic

  • Lead Acid RechargingLow self-discharge40% in one year (three months for NiCd)No memoryCannot be stored when dischargedLimited number of full dischargesDanger of overheating during charging

  • Lead Acid BatteriesRatingsCCA: cold cranking amps (0F for 30 sec)RC: reserve capacity (minutes at 10.5v, 25amp)Deep discharge batteriesUsed in golf carts, solar power systems2-3x RC, 0.5-0.75 CCA of car batteriesSeveral hundred cycles

  • Lithium Ion BatteriesChemistryGraphite (-), cobalt or manganese (+) Nonaqueous electrolyteFeatures40% more capacity than NiCdFlat discharge (like NiCd)Self-discharge 50% less than NiCdExpensive

  • Lithium Ion Recharging300 cycles50% capacity at 500 cycles

  • Lithium Ion Polymer BatteriesChemistryGraphite (-), cobalt or manganese (+)Nonaqueous electrolyteFeaturesSlim geometry, flexible shape, light weightPotentially lower cost (but currently expensive)Lower energy density, fewer cycles than Li-ion

  • Battery Capacity

    TypeCapacity (mAh)Density (Wh/kg)Alkaline AA2850124 Rechargeable160080NiCd AA75041NiMH AA110051Lithium ion1200100 Lead acid200030

  • Discharge Rates

    TypeVoltagePeak DrainOptimal DrainAlkaline1.50.5C< 0.2CNiCd1.2520C1CNickel metal1.255C< 0.5CLead acid25C0.2CLithium ion3.62C< 1C

  • Recharging

    TypeCycles (to 80%)Charge timeDischarge per monthCost per kWhAlkaline50 (50%)3-10h0.3%$95.00NiCd15001h20%$7.50NiMH300-5002-4h30%$18.50Li-ion500-10002-4h10%$24.00 Polymer300-5002-4h10%Lead acid200-20008-16h5%$8.50

  • Example: IBM ThinkPad T21 Model 2647Source: IBM datasheetRelatively-constant discharge

  • Lithium-ion Batteries in NotebooksLithium: greatest electrochemical potential, lightest weight of all metalsBut, Lithium metal is explosiveSo, use Lithium-{cobalt, manganese, nickel} dioxideOvercharging would convert lithium-x dioxide to metallic lithium, with risk of explosion

    *Daniell cell was first reliable source of energySolved corrosion problems in Voltaic cell*1957 9v battery introduced1991 Early lithium battery recall (mobile phone battery burst into flame)

    *A battery contains two or more cellsAll products here are dry cells (car batteries are wet cells) ***********Used in power toolsUse restricted in some countries

    ***Alternative to NiCd

    *****Sold by Rayovac

    ********Sources differ as to exact numbersDensity should take packaging into account, not just chemistryConsult product specification sheets*Drain of one C exhausts capacity in one day

    *