Lead–acid Batteries for Hybrid Electric Automobiles What is a hybrid electric vehicle? What does it do? What does the battery have to do? What are the candidate batteries? How should we choose between them? SLI only ISG Series hybrid Parallel hybrid Electric drive Battery (size proportional to capacity) Generator / motor Electrical energy flow (flow rate proportional to thickness) Mechanical energy flow (flow rate proportional to thickness) Types of Hybrid Electric Automobile Micro- Mild- Medium Full EV Drive Motor assist Regen. braking Engine stop Battery voltage 12 36 144 >200 Battery capacity 50 - 60 15 - 20 6 - 8 6 (Ah) State-of-charge of battery 100 50 + 3% 50 50 - 3% State-of-Charge / % State-of-Charge / Time Charge and discharge currents experienced by ‘Insight’ battery during hard driving 100 80 60 40 20 0 0 500 1000 1500 2000 -20 -40 -60 Current A -80 -100 Time (secs) Typical range of state-of-charge, rates of discharge and recharge and failure modes Duty SLI Deep cycle High rate PSoC Examples 12 V EV HEV , UPS, PV Range of SoC 85 - 90 % 20 - 100 % 50 - 70, 70 - 90 % Max. norm. 10 C 4 C 15 C disch. rate Max. norm. 0.5 C 0.5 C 8 C charge rate Life-limiting Corrosion, PCL 1, mechanisms shedding PCL 2 ? What factors should be considered when selecting a battery for an HEV? Cost Weight Life Lead sulfate Grid – – HSO4 HSO4 Grid Negative active-material Grid H2 H2 2 e– Lead sulfate H2 H2 2 e– Negative active-material Characteristics of high-rate partial-state-of-charge operation 1. High rate - up to 15 C discharge and 8 C charge 2. Long periods without approaching top-of-ch. 3. Very large number of (small) cycles - 300,000 rather than < 1,000. EoC and EoD potentials of negative plates in HRPSoC operation CB1 (0.2 wt.%) – 1.6 CF1 (2.0 wt.%) 4 4 – 1.4 CB1 (2.0 wt.%) GR2 (2.0 wt.%) SO SO 2 2 – 1.2 CB2 (2.0 wt.%) CB3 (2.0 wt.%) Hg | Hg Hg | Hg | Hg Hg | CB4 (2.0 wt.%) vs vs – 1.0 CB5 (0.4 wt.%) – 0.8 Potential – 0.8 Potential – 0.6 0 1000 2000 3000 4000 5000 Number of HEV cycles Medium Hybrids Key FreedomCAR Performance Goals Characteristic Units Min. Power-assist Max. Power-assist 10 s Disch. power kW 25 40 10 s charge power kW 20 35 Available energy kWh 0.3 0.5 Weight kg 40 60 Cycle life cycles 300,000 300,000 Derived parameters Specific disch. power W kg-1 625 667 Specific ch. power W kg-1 500 583 Specific energy Wh kg-1 7.5 8.3 VRLA Batteries designed for power-assist operation Battery type, Design elements Specific power manufacturer (W kg-1) ‘RHOLAB’ (8Ah) Twin-tab to boost 600 Enersys Power, spiral Bipolar (8Ah) Bipolar plate Pb- 1000 Effpower Impreg ceramic Ultra (8.5Ah) Additional carbon 500 - 600 Furukawa/CSIRO Capacitive element The First Test Vehicle Project Effpower ALABC Identifier:Effpower Battery type: Bipolar, 8 Ah, 144V Vehicle: Honda Insight Voltage: 144V BATTERY MANAGEMENT • Honda Insight Battery Management System supplied and installed by PROVECTOR • Add-ons including CAN interface, OBD2 module and GPS module • Effpower cell monitoring system Project ‘Ultra’ ALABC Identifier: DP 1.1 Battery type: Furukawa/CSIRO flat, 7 Ah, 12V Vehicle: ALABC Honda Insight Voltage: 144V Configuration of the Ultrabattery + – Separator + – PbO2 Carbon PbO 2 Pb electrode Lead–acid cell Asymmetric supercapacitor + i – i1 Pb i i2 Ultrabattery Carbon electrode Ultrabattery is a hybrid energy-storage device, which combines an asymmetric capacitor and a lead-acid battery in one unit cell, without extra electronic control. Hybrid pulse power characterisation (maximum power assist, battery-size factor = 35) Discharge power = 40 kW Charge power = 35 kW 80000 70000 y = 2E-06x3 - 0.0207x2 + 59.285x + 875.37 y = 4E-07x3 - 0.0069x2 + 4.6404x + 61819 R2 = 0.9997 70000 60000 R2 = 0.9998 60000 50000 50000 40000 40000 30000 30000 Available energy = 1550 Wh 20000 20000 Available energy goal = 500 Wh 10000 10000 10-s charge power / W x BSF 10-s discharge power / W x BSF 0 0 0 300 600 900 1200 1500 1800 2100 2400 2700 3000 1-h discharge energy / Wh x BSF High-speed and hill-climbing driving profile 0.11 Ah Charge 1200 Ultrabattery 45% DoD Ultracells (8 Ah battery) 1000 -3.63 Ah Discharge 800 600 Cycling procedure: discharge the cell/battery to 80% SoC and Cycle number 400 then subject to the above profile repetitively Control cells until the minimum voltage reaches 0 V. Control battery 200 Performance: at least four times longer in cycle-life than the state-of-the art VRLA cells 0 C1 C2 CB UC1 UC2 UC3 UB CyclingCycling PerformancePerformance (Under(Under EUCAREUCAR PowerPower AssistAssist Profile)Profile) Power-assist HEVs on Road Test with VRLA batteries Battery for a Power-assist HEV (~1kWh) NiMH Li-Ion VRLA Freed’car Min.Goals Weight (kg) 23.26 12.5 33.3 40 (inc. (excl. BMS) BMS) Cost, $ (raw 349 74 58 500 whole materials) Ni - lme Li - USGS Pb - lme battery Life - cycles 300,000 ? 200,000+ 300,000 Life - miles 100,000+ ? 50,000++ 100,000 If hybrid electric vehicles are to contribute meaningfully to reductions in pollution, in greenhouse gasgas emissionsemissions and to relieving the pressure on world oil supplies they must be adopted in very large numbers. In order for this to happen such vehicles must be affordable… .