EV101: Owning and Operating an Electric Vehicle

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

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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

Traction Batteries
Charger
DC-DC
Contactors
Speed Pedal
Motor Controller
Aux. Battery
Contactors
Motor
Differential
Just like a toy car, but high voltage and high
current (danger!)
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Throttle Linkage
Zap Throttle Linkage
Converted Honda Insight Linkage
Electric Output
S10 Electric Pickup Linkage
Mechanical Input
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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
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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
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DC-DC Converters

• Most EVs have small 12V aux. battery
• Runs lights, horn, etc
• Runs motor controller logicneeded 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
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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

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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 lt 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 wont do this)

Running batteries down and letting them sit
discharged is very bad for them
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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 circuitdont 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

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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)

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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
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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 its 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
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Use Appropriate Batteries
12V batteries need sufficient power to stay above
10.5V (short bursts ok)
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Past Time for a New Pack
2V differences indicate exhausted or reversed
cells
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Battery Management Add-ons

• Hart Batt-Bridge is an idiot light costing lt10
• LED lights when two halves of pack differ by gt 2v
• One cell empties/reverses first
• Charge now or go turtle mode!
• PowerCheq modules
• Keep each two adjacent batteries voltage
  difference lt .1V
• Works 24X7 while driving, charging, parked
• Limited currentkeeps balanced pack balanced
• Requires N-1 modules for N batteries

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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

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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

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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
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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

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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 EVs 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
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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
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Solar Powered Electric Vehicles
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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
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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

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Fuel Efficiency and Climate Change
Vehicle Type Gas 25 Mi. /Day kWh 25 Mi. /Day /year 25 Mi. /Day Gal/yr 25 Mi. /Day 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 0 5 100 0 0 .7
Battery EV 0 3 65 0 0 .4
Solar/Electric 0 1 0 0 0 ZERO

Assumptions 3.50/gal, .05/kWh nighttime rate,
40kWh/gal, 23sCO2/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.
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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
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Global Energy Potential
Renewables Forever
terawatt hours/YEAR
Direct Solar Radiation
350,000,000 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 its gone)
terawatt hours TOTAL
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) 1,000,000 Tar Sands
800,000
World stored energy consumption 70,000 terawatt
hours/year
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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

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Backup
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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
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US Oil Discoveries Peaked in 1930 US Oil
Extraction Peaked in 1970
America is Addicted to Oil
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.

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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 2005-2010
J. Mackenzie, WRI 2007-2014
International Energy Agency 2010-2020
US DOE lt 2020

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.
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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

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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