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The Science of Electric Vehicles
Alan Soule and Chris J onesNorth Bay Electric Auto Association
www.nbeaa.org
Presentation to Science Buzz CafFrench Garden Restaurant, Sebastopol
J uly 22, 2010 6:30 PM
This presentation is posted atwww.nbeaa.org/presentations/ev_science.pdf.
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Alan Soule
NBEAA PR Director
Tesla Roadster owner
Chris J ones
NBEAA President
Mustang EV Converter
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Agenda
Reasons to Drive an EV
EV Components
Buying an EV
Driving an EV
The Tesla Roadster
EV Show and Tell
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Energy Independence
60% of 2006 US oil consumption was imported per the US Government EnergyInformation Administration Basic Petroleum Statistics,www.eia.doe.gov/neic/quickfacts/quickoil.html.
Greenhouse Gas Reduction
Transportation accounted for 42% of greenhouse gas emissions in Sonoma County in2000, according to the Climate Protection Campaigns J anuary 2005 reportGreenhouse Gas Emission Inventory for all sectors of Sonoma County, California,www.climateprotectioncampaign.org/news/documents/AP_INVEN.PDF.
Air and Water Pollution Reduction
Asthma cost $12.7B in 1998 and can be caused by vehicle exhaust, per the Center forDisease Control Asthma Speakers Kit, www.cdc.gov/asthma/speakit/default.htm.
See www.nbeaa.org/bev_faq.htmfor more frequently asked EV questions.
Reasons to Drive an EV
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Energy Independence
Efficiency: Petrol ICE
EVs charged by
ICE grid
EVs offset by PVsmade by ICE grid
EVs offset by PVsmade by PV grid
Combustion 15% 35% 35% n/a
Grid n/a 90% 90% 90%
Energy Generation n/a n/a 300% 300%
Charger n/a 90% 90% 90%
Battery n/a 90% 90% 90%
AC Drive System n/a 85% 85% 85%
TOTAL 15% 21% 63% Infinite for 5.5B years
Efficiency of fuel input to motor shaft output only. Energy to make EV can be higher, but it makes up a small amount of the
total energy consumed from cradle to grave of an ICE. Emissions vary based on type of fuel used to power the grid.
Non-RenewableEnergyConsumed:
100%
71%
24%
0%
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Greenhouse Gas Reduction
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Cost
The great news: EVs cost far less to operate.
Tesla Roadster: 71% less
gas (Lotus Elise): $3 per gallon / 22 MPG = $.14 per mile
electric: $.12 per kWh / 3.5 miles per kWh = $.04 per mile
Mustang Conversion: 60% lessgas: $3 per gallon / 20 MPG = $.15 per mileelectric: $.12 per kWh / 2.0 miles per kWh = $.06 per mile
Note: charging at peak rate is more, but less with an E9 Time of
Use PG&E meter, solar, or free work or public charging.
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Cost
The bad news: EVs can cost more to own overall if you purchase or
convert one with advanced technology, and gas prices remain low.The following examples for our vehicles assume car is scrapped in 10 years, the batteries
deliver enough power and capacity for the life of the car, there is no significantdifference in maintenance cost, and gas prices do not increase.
Mustang Gas electric
Car purchase $10,000 $10,000 donor car
$30,000 EV conversion
Fuel to travel 73K miles
20 miles per day
50% DOD
$10,950 $4,380
Total $20,950 $44,380
$23,430 more
$6.42 more per day:2 medium Peets lattes
Tesla Gas (Lotus Elise) electric
Car purchase $60,000 $109,000
Fuel to travel 150K miles
41 miles per day
18% DOD
$21,000 $6,000
Total $81,950 $115,000
$33,050 more
$9.05 more per day: 3 medium Peets lattes
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Cost
The good news: EVs will cost less to own if EV prices come down, or if
EV incentives or gas prices go up.
The following example for the Nissan Leaf assumes car is delivered as announced, isscrapped in 10 years, the batteries deliver enough power and capacity for the life of thecar, there is no significant difference in maintenance cost, andgas prices do notincrease.
Leaf Gas (Versa hatchback) electric
Car purchase $15,000 $25,000 after federal rebate
Fuel to travel 150K miles
41 miles per day
18% DOD
$16,071 at 28 MPG $6,000
Total $31,107 $31,000
$107 more
$.03 more per day: same cost at $3 per gallon
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EV Components
Motor Batteries and Electronics
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2-Pole Series Wound DC Motor Demonstration
BrushCommutator
Field Windings Armature Windings
Current flows through the brushes, commutator, armature windings and field windings to create
electromagnetic forces that oppose each other, which causes the armature to turn.
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Electric Motor Types
No
Yes
No
Yes
Yes
Yes
brushes
Opposing magnetic field inducedvia eddy currents caused by slipbetween stator and rotor in copperor aluminum squirrel cageframe
Armature windings, PWMdvia rotor position sensor
AC Induction
Field windings, DC energizedthrough brushes and slip rings
Armature windings, PWMdvia rotor position sensor
AC Synchronous
Field permanent magnetArmature windings, PWMdvia rotor position sensor
DC BrushlessPermanent Magnet
Armature windings, commutatedthrough brushes
Field permanent magnetDC BrushedPermanent Magnet
Armature windings, commutatedthrough brushes, separatelyexcited from field
Field windingsDC Shunt
Armature windings, commutatedthrough brushes and split rings, inseries with field
Field windingsDC Series
Rotor (rotating part)Stator (stationary part)type
The fieldproduces a magnetic field to be acted upon by armature; it can be an electromagnet orpermanent magnet. The armaturecarries current normal to field to generate torque.
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Electric Motor Types
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Nail / Tube / Salt Water Battery Demonstration
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Nail / Tube / Salt Water Battery Demonstration
A chemical reaction between the zinc nail, salt water and copper tube causes current to flow through
the LED, which causes it to light up.
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Battery Types
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Batteries in Development
Stanford University Silicon Nanowireelectrodes have 3X capacityimprovement expected for Lithiumbatteries
Not technically a battery, but MITNanotube ultracapacitors have veryhigh power, 1M+ cycle energystorage approaching Lithium batterycapacity
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Motor and Battery Charge Control via Pulse Width Modulation
100%duty cycle
75%
50%
25%
0%
on
off
on
off
on
off
on
off
on
off
time
Reducing the duty cycle reduces the power delivered to the load.
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Switch Mode Power Supply Buck Regulator:a common building block for motor and charge control
Frompower
source:batteries,grid or
motor inregenmode
To load: motor orbatteries
Power switchingtransistors: MOSFETs
or IGBTs
FromPWMcontrolcircuit
Freewheeldiodes
Filtercapacitors
When power is applied to input, capacitors are charged up. When transistors are switched on, current flowsfrom the batteries and capacitors to the motor. When the transistors are off, the capacitors are recharged by
the batteries while current flows from the motor to the freewheel diodes while the motors magnetic fieldcollapses to keep from increasing the voltage across the transistor to the point of failure.
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Buying an EV
in the U.S.
Refer to Plug In America Plug-in vehicle tracker
Currently available EVs in California:Tesla Roadster ($109,000)
EVs Scheduled for production:Audi e-tron 2011 ?BMW ActiveE 2011 ?CODA 2010 $45,000Daimler Smart EV 2012 ?Ford Focus 2011 ?
Hyundai i10 Electric 2012 ?Mitsubishi iMiEV 2010 $47,000Nissan Leaf 2011 $22,000Peugeot iOn 2011 ?Rolls Royce 2010 ~$500,000Tesla Model S 2012 $50,000
Toyota Rav4 (Tesla drivetrain) 2012 ?
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Driving an EV
The process of driving an EV is no different than drive an ICE car High torque for quick acceleration No shifting (no transmission) Regenerative braking monitoring your speed with the gas pedal No loss of Range going up hill, as long as you come down Charging outdoors in the rain is not a problem
Accurate metering of charge to monitor how much Range is left HOV exemption for EVs until the end of 2015
Range is the biggest concern Charge at home at night and start out every day with full Range Wind resistance is the biggest factor affecting Range
Currently, a trip that requires charging, requires planning becauseof limited public chargers
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ELECTRICAL CAPACITY: 52.8 KWHR
CELL CAPACITY: 7.73 WHR (2.2 AMPHR)
QUANTITY OF CELLS: 6,831CELLS PER BRICK: 69
BRICKS PER MODULE: 9
MODULES PER BATTERY: 11
BATTERY WEIGHT: 970 LB.S (CHARGED OR NOT)
ELECTRON CAPACITY: 34.1328 X 10 to the 23rd
WEIGHT OF FUEL: 0.003089 grams (GRAIN OF SALT)
CRASH TEST: 50 MPH REAR IMPACT
ACID LEAK TEST HANG CAR VERTICALLY FOR 12 HR.S
Tesla Roadster
TESLA BATTERY
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TESLA MOTOR
375 volt AC induction air-cooled electric motor with variable frequency drive
Max Net Power: 248 HP (185 kW) @ 5000-8000 rpm (40-65 MPH)
Max rpm 14,000 Efficiency 92% average, 85% at peak power
Torque 276 ft/lb (375 Nm) @ 0-4500 rpm (0-40 MPH)
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TESLA TRANSMISSION
Single speed fixed gear with electrically-actuated parking lock mechanismand mechanical lubrication pump
Overall Final Drive 8.28:1
Reverse direction of motor, limited to 15 mph
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Tesla Battery Fabrication and Disposal
Lithium is the lightest naturally occurring element
Largest Producers are located in Chile (65% of worlds total), Argentina,Australia and China with a large deposit being developed in Bolivia
Largest manufacturer of Lithium products is China
Tesla battery is manufactured in J apan. The manufacturer complies withthe Directive on the Restriction of the Use of Certain HazardousSubstances in Electrical and Electronic Equipment
After use in the car, batteries can be used to level off grid power
The battery modules will be recycled by Toxco in British Columbia
The results of the current recycling process are:60% of the materials are recycled10% of the materials are reused25% of the materials are disposed of
http://www.teslamotors.com/blog/mythbusters-part-3-recycling-our-non-toxic-battery-packs
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