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

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ev101 owning and operating an electric vehicle

EV101: Owning and Operating an Electric Vehicle

Gary Graunke

Oregon Electric Vehicle Association

(Oregon chapter of the Electric Auto Association)

December, 2007

slide2

Gratefully acknowledging many slides fromSteve HeckerothDirector of BIPV, ECD OvonicsChair Renewable Fuels and Sustainable Transportation Division of the American Solar Energy Society

agenda
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
how electric cars work
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!)

throttle linkage
Throttle Linkage

Zap Throttle Linkage

Converted Honda Insight Linkage

Electric Output

S10

Electric

Pickup

Linkage

Mechanical Input

motor controllers
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

series chargers
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

dc dc converters
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

agenda9
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
ev maintenance
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

managing safety issues
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
proper tools for safety
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)
battery balancing
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

capacity variance with aging
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

use appropriate batteries
Use Appropriate Batteries

12V batteries need sufficient power to stay above 10.5V (short bursts ok)

past time for a new pack
Past Time for a New Pack

2V differences indicate exhausted or reversed cells

battery management add ons
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
more battery management aids
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
agenda19
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
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

Costs of EV Operation

EV owners replace batteries when heat engine owners replace vehicle

agenda21
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
uses for electric vehicles
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

electric motor torque and power
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

slide25

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

agenda26
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
fuel efficiency and climate change
Fuel Efficiency and Climate Change

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.

the real measure of efficiency
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

1.2x1012TWh Solar Energy=1 TWh Oil Energy

Using direct solar energy is 1,200,000,000,000 X more efficient than using oil

global energy potential

Renewables Forever

terawatthours/YEAR

Global Energy Potential

Direct Solar Radiation350,000,000 Wind 200,000

Ocean Thermal 100,000

Biofuel 50,000

Hydroelectric 30,000

Geothermal 10,000

Tidal/Wave 5,000

Energy Stored in the Earth

(Use it once and it’s gone)

terawatthoursTOTAL

Coal 6,000,000

Natural Gas (US Peak 2004) 1,500,000

Uranium 235 (US Peak 2008) 1,500,000

Petroleum (US Peak 1970, World Peak 2010) 1,000,000Tar Sands 800,000

World stored energy consumption = 70,000 terawatt hours/year

agenda30
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
the fossil fuel age on the scale of human history
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 for12,000 years without diminishing its bounty

us oil discoveries peaked in 1930 us oil extraction peaked in 1970

“ America is Addicted to Oil”

US Oil Discoveries Peaked in 1930US Oil Extraction Peaked in 1970

US Oil Consumption

Will Peak200?

  • 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.
world peak oil
World Peak Oil

Gray Area Shows the

Range of Forecast Peak Conventional Oil Reserves

Source Peak Date

Petroleum Industry 2020-2040

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.

advantages of sustainable energy
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
slide37

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