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EV101: Owning and Operating an Electric Vehicle

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Presentation on theme: "EV101: Owning and Operating an Electric Vehicle"— Presentation transcript:

1 EV101: Owning and Operating an Electric Vehicle
Gary Graunke Oregon Electric Vehicle Association (Oregon chapter of the Electric Auto Association) December, 2007

2 Gratefully acknowledging many slides from Steve Heckeroth Director of BIPV, ECD Ovonics Chair Renewable Fuels and Sustainable Transportation Division of the American Solar Energy Society

3 Agenda How electric cars work Maintenance on an electric car
Costs of operation Uses for electric cars Sustainable transportation vs fossil fuels Questions and Answers

4 How Electric Cars Work Throttle variable resistor tells motor controller desired speed Like radio volume control Motor controller varies pulse width to motor Rapidly switches battery voltage on and off Contactors (relays) may be used to reverse motor Other contactors used for safety disconnect Charger recharges batteries from grid DC-DC converter charges low voltage “starter” battery from high voltage pack Charger Traction Batteries DC-DC Contactors Speed Pedal Motor Controller Aux. Battery Contactors Motor Differential Just like a toy car, but high voltage and high current (danger!)

5 Throttle Linkage Zap Throttle Linkage Converted Honda Insight Linkage
Electric Output S10 Electric Pickup Linkage Mechanical Input

6 Motor Controllers DC motor controllers pulse high voltage to motor
Pulse width controls speed Relays used to reverse motor Some motor controllers do regenerative braking Slows vehicle by generating electricity from motion Recharges batteries Curtis 1231C (ZAP) Contactors (ZAP) CafeElectric Zilla 1K Electricity is the only alternative fuel you can create when you go downhill

7 Series Chargers Proper charging is important for battery life!
Each battery has its own protocol Initial bulk charge usually constant current (max power) Finishing charge is constant voltage (power decreases) DeltaQ charger (ZAP) Brusa NLG512 charger Manzanita Micro PFC

8 DC-DC Converters Most EV’s have small 12V aux. battery
Runs lights, horn, etc Runs motor controller logic—needed to start Small: no engine to start! DC-DC charges aux battery from high voltage pack Voltage change Isolation (safety) Some are integrated with motor controller Zap DC-DC

9 Agenda How electric cars work Maintenance on an electric car
Costs of operation Uses for electric cars Sustainable transportation vs fossil fuels Questions and Answers

10 EV Maintenance Tires and brakes are the same as gas cars
Regenerative braking reduces brake wear No filters, mufflers, oil changes, engine valves, rings, pollution control, fuel pumps Care and feeding of (lead acid) battery pack Ideally charge when 50% and 70% left Avoid discharge < 20% state of charge Leaving discharged causes sulfation in lead batteries Keep lead-acid batteries topped up Batteries self-discharge (charge periodically if not in use) Avoid overcharging (good chargers won’t do this) Running batteries down and letting them sit discharged is very bad for them

11 Managing Safety Issues
Service disconnects to break HV battery string into small parts Voltages must be below 60V to be “safe” High voltage, high current shorts can cause plasma fires Maintain isolation of HV pack and chassis Need two connections to form circuit—don’t give up this advantage! Remove rings while working on battery pack High currents can weld objects Batteries must be securely fastened down Use DC-rated fuses, switches, relays DC ratings are typically 1/3 of AC ratings Flooded batteries may explode--wear eye protection Flooded batteries can spill H2SO4, KOH Overcharging (mostly flooded) may produce explosive H2 Nevertheless, electricity has safety advantages Does not leak into air and explode/catch fire Easily stopped by fuse or switch anywhere in circuit

12 Proper Tools for Safety
Electrical tape on metal sockets and other wrenches Rubber handle wrenches Rubber gloves Certified if higher voltages Fiberglass shaft screwdrivers / nutdrivers Certified and isolated test equipment (meters and scopes)

13 Battery Balancing Relative cell state of charge varies over time
Manufacturing variance Different operating temperature Series charging increases differences in state of charge Individual chargers is one solution Stop driving when lowest cell is empty Stop charging when highest cell is full (5% overcharge ok) But charger and instruments measure total pack voltage Ideally measure individual cell voltages Measuring highest, lowest batteries is good approximation full 2.16V voltage empty 1.75V overcharge full voltage empty Periodic rebalancing improves battery pack longevity

14 Capacity Variance with Aging
Overdriving As batteries age capacity variances increase More imbalance! Easier to overdrive Weakest cell voltage plunges and may even reverse polarity! Best case: shorter range Low temperatures also reduce effective capacity Eventually it’s time for a new pack! Lowest capacity cell is also overcharged Active automatic battery balancers mitigate extremes full 2.16 voltage empty 1.75 0 volts overcharging full voltage empty Check aging pack batteries for varying capacity

15 Use Appropriate Batteries
12V batteries need sufficient power to stay above 10.5V (short bursts ok)

16 Past Time for a New Pack 2V differences indicate exhausted or reversed cells

17 Battery Management Add-ons
Hart Batt-Bridge is an “idiot light” costing <$10 LED lights when two halves of pack differ by > 2v One cell empties/reverses first Charge now or go “turtle mode”! PowerCheq modules Keep each two adjacent batteries voltage difference < .1V Works 24X7 while driving, charging, parked Limited current—keeps balanced pack balanced Requires N-1 modules for N batteries

18 More Battery Management Aids
Manzanita Micro MK3 regulator prevents overcharge Backs off charger when individual battery full Limits battery voltage Data logging Hart balancer relay module (30A capacity) Scans batteries to measure voltage Connects any battery to isolated “flying” battery or DC-DC Can take charge from higher state-of-charge batteries Gives charge to lower state-of-charge batteries

19 Agenda How electric cars work Maintenance on an electric car
Costs of operation Uses for electric cars Sustainable transportation vs fossil fuels Questions and Answers

20 Costs of EV Operation Top EV cost is battery wear
3 to 15 cents / mile Assumes proper care! Fuel cost 2-3 cents/mi 10 cents/KWH and 4-8 mi/KWH 1 US gal gas = 33 KWH S10: 66 mpg equivalent NEV: 245 mpg equivalent Electric motors last! AC motors: 1 moving part DC motors: brushes Top heat engine cost is maintenance 28 cents / mile (CARB) Engine/drive train wear Currently 10 cents/mi $3.00/gal and 30 mpg Geologists, investment bankers say global oil production has peaked Expect unlimited price increases EV owners replace batteries when heat engine owners replace vehicle

21 Agenda How electric cars work Maintenance on an electric car
Costs of operation Uses for electric cars Sustainable transportation vs fossil fuels Questions and Answers

22 Uses for Electric Vehicles
Pure electric vehicles Daily commuting and in-town driving Great for circular business delivery routes (e.g., mail carriers) Excellent for short trips (no engine warm-up needed) Efficient and non-polluting even when “cold” Prius gets 25 mpg for first 5 minutes! Some vehicles may have speed limits Freeway capable EV’s exist (mostly conversions for now) Range is only limiting factor (may be reduced in winter) Low battery specific energy vs heat engine fuel Lack of rapid recharging/battery swapping infrastructure Hybrid (HEV) and Plug-in Hybrid Electric Vehicles (PHEV) Better (+50%) range for long trips + efficiency Honda Insight (EPA 70 mpg) owners often report 1000 miles/tank Plug-in Prius (Hybrids Plus) 1620 mi on 9.27 gal (171 mpg + electricity) Consider Budget/Flexcar for those infrequent long trips

23 Electric Motor Torque and Power
Siemens 5105WS12 at 312 Volts Insight torque 79 ft lbs at 1500 RPM Insight power 54.4 KW at 5700 RPM

24 Solar Powered Electric Vehicles

25 Almost Half a MWh of storage in the parking lot
The Clean Power/Transportation Solution 2 kW of PV per parking space PV charging infrastructure combined with plug-in vehicles tied to the grid (V2G) will provide peak shaving, load leveling and backup power. EVs and PVs in the parking lot or garage can power a factory or home. Almost Half a MWh of storage in the parking lot Photo courtesy Donald Aitkin

26 Agenda How electric cars work Maintenance on an electric car
Costs of operation Uses for electric cars Sustainable transportation vs fossil fuels Questions and Answers

27 Fuel Efficiency and Climate Change
Vehicle Type $ Gas 25 Mi. /Day kWh 25 Mi. /Day $/year Gal/yr Tons of CO2/Yr Tailpipe *+ Tons of Upstream CO2/Year 10 MPG Gas 8.75 100 $3200 915 10.5 13.7 20 MPG Gas 4.37 50 $1600 460 5.3 6.8 30 MPG Gas 2.93 34 $1050 305 3.5 4.5 40 MPG HEV 2.20 25 $800 230 2.6 3.4 50 MPG HEV 1.75 20 $640 180 2.1 2.8 Plug-in HEV 25 Mile range 5 $100 .7 Battery EV 3 $65 .4 Solar/Electric 1 ZERO Assumptions: $3.50/gal, $.05/kWh nighttime rate, 40kWh/gal, 23#sCO2/gal * This column includes upstream CO2 emissions for exploration, extraction, transport, refining and distribution of gasoline, as as well as CO2 emissions from the California mix of power plants that produce electricity to charge electric vehicles.

28 The real measure of efficiency
It took 3.5 billion years and rare geologic events to sequester hydro carbons and build up O2 in the atmosphere 3.5x109 Years X 3.5x108 TWh/year Solar Energy = 1x106 TWh Oil Total 1.2x1012 TWh Solar Energy = 1 TWh Oil Energy Using direct solar energy is 1,200,000,000,000 X more efficient than using oil

29 Global Energy Potential
Renewables Forever terawatt hours/YEAR Direct Solar Radiation ,000, Wind ,000 Ocean Thermal ,000 Biofuel ,000 Hydroelectric ,000 Geothermal ,000 Tidal/Wave ,000 Energy Stored in the Earth (Use it once and it’s gone) terawatt hours TOTAL Coal ,000,000 Natural Gas (US Peak 2004) ,500,000 Uranium 235 (US Peak 2008) ,500,000 Petroleum (US Peak 1970, World Peak 2010) ,000,000 Tar Sands ,000 World stored energy consumption = 70,000 terawatt hours/year

30 Agenda How electric cars work Maintenance on an electric car
Costs of operation Uses for electric cars Sustainable transportation v.s. fossil fuels Questions and Answers


32 Backup

33 The fossil fuel age on the scale of human history
In 150 years of burning fossil fuel the Earths 3 billion year store of solar energy has been plundered Native Americans lived on this land for 12,000 years without diminishing its bounty

34 US Oil Discoveries Peaked in 1930 US Oil Extraction Peaked in 1970
“ America is Addicted to Oil” US Oil Discoveries Peaked in US Oil Extraction Peaked in 1970 US Oil Consumption Will Peak 200? Reality Check: This is not a projection it is historical data from the petroleum industry. In a more perfect world the US might have noticed a trend after discoveries peaked in 1930. In a less than perfect world the US would have responded to peak extraction around 1975. Ignoring the realities of finite resources puts future generations at risk. We are the future generation.

35 Range of Forecast Peak Conventional Oil Reserves
World Peak Oil Gray Area Shows the Range of Forecast Peak Conventional Oil Reserves Source Peak Date F. Bernabe, ENI SpA 2005 C. Campbell, Petroconsultants J. Mackenzie, WRI International Energy Agency US DOE < 2020 Source Peak Date Petroleum Industry US Oil “production” has been declining at an average of 2%/year since 1985. US Oil imports have been increasing at an average of 4%/year since 1985.

36 Advantages of Sustainable Energy
Fossil Fuel Dependence Solar Independence Finite fuel supply Ugly infrastructure Polluted air / Climate change Extraction site devastation Polluted land Spills and polluted water Energy resource wars Susceptible to terrorism Unlimited energy source Aesthetically superior Clean air / Zero emissions No extraction sites Healthy land No water pollution No conflict over free sunshine National and individual security

37 Solar/Electric Economy
QUALITY OF LIFE FUSSIL FUEL USE RENEWABLE ENERGY USE Combustion Economy combustion depletes stored energy resources, reduces the quality of essential resources and will cause conflict and economic collapse Agrarian Economy Reliance on fossil energy has allowed population growth that can not be sustained by manual labor or beasts of burden Solar/Electric Economy Moving toward reliance on clean energy from the sun will stabilize the quality of essential resources and allow positive evolution

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