The Science of Electric Vehicles

Alan Soule and Chris JonesNorth Bay Electric Auto Association

www.nbeaa.org

Presentation to Science Buzz CaféFrench Garden Restaurant, Sebastopol

July 22, 2010 6:30 PM

This presentation is posted at www.nbeaa.org/presentations/ev_science.pdf.

Alan Soule

NBEAA PR Director

Tesla Roadster owner

Chris Jones

NBEAA President

Mustang EV Converter

Agenda

Reasons to Drive an EV

EV Components

Buying an EV

Driving an EV

The Tesla Roadster

EV Show and Tell

Energy Independence

60% of 2006 US oil consumption was imported per the US Government Energy Information 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 in 2000, according to the Climate Protection Campaign’s January 2005 report “Greenhouse 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 for Disease Control “Asthma Speaker’s Kit”, www.cdc.gov/asthma/speakit/default.htm.

See www.nbeaa.org/bev_faq.htm for more frequently asked EV questions.

Reasons to Drive an EV

Energy Independence

Efficiency: Petrol ICEEVs charged byICE 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-Renewable Energy Consumed:

100%

71%

24%

0%

Greenhouse Gas Reduction

Cost

The great news: EVs cost far less to operate.

Tesla Roadster: 71% lessgas (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% less gas: $3 per gallon / 20 MPG = $.15 per mile electric: $.12 per kWh / 2.0 miles per kWh = $.06 per mile

Note: charging at peak rate is more, but less with an E9 Time ofUse PG&E meter, solar, or free work or public charging.

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 significant difference 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 miles20 miles per day50% DOD

$10,950 $4,380

Total $20,950 $44,380$23,430 more$6.42 more per day: 2 medium Peet’s lattes

Tesla Gas (Lotus Elise) electric

Car purchase $60,000 $109,000

Fuel to travel 150K miles41 miles per day18% DOD

$21,000 $6,000

Total $81,950 $115,000$33,050 more$9.05 more per day: 3 medium Peet’s lattes

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, is scrapped in 10 years, the batteries deliver enough power and capacity for the life of the car, there is no significant difference in maintenance cost, and gas prices do not increase.

Leaf Gas (Versa hatchback) electric

Car purchase $15,000 $25,000 after federal rebate

Fuel to travel 150K miles41 miles per day18% 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

EV Components

Motor Batteries and Electronics

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.

Electric Motor Types

No

Yes

No

Yes

Yes

Yes

brushes

Opposing magnetic field induced via eddy currents caused by slip between stator and rotor in copper or aluminum “squirrel cage” frame

Armature windings, PWM’dvia rotor position sensor

AC Induction

Field windings, DC energized through brushes and slip rings

Armature windings, PWM’dvia rotor position sensor

AC Synchronous

Field permanent magnetArmature windings, PWM’dvia rotor position sensor

DC Brushless Permanent Magnet

Armature windings, commutated through brushes

Field permanent magnetDC Brushed Permanent Magnet

Armature windings, commutated through brushes, separately excited from field

Field windingsDC Shunt

Armature windings, commutated through brushes and split rings, in series with field

Field windingsDC Series

Rotor (rotating part)Stator (stationary part)type

The “field” produces a magnetic field to be acted upon by armature; it can be an electromagnet or permanent magnet. The “armature” carries current normal to field to generate torque.

Electric Motor Types

Nail / Tube / Salt Water Battery Demonstration

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.

Battery Types

Batteries in Development

Stanford University Silicon Nanowire electrodes have 3X capacity improvement expected for Lithium batteries

Not technically a battery, but MIT Nanotube ultracapacitors have very high power, 1M+ cycle energy storage approaching Lithium battery capacity

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.

Switch Mode Power Supply Buck Regulator: a common building block for motor and charge control

From power

source: batteries,

grid or motor in regenmode

To load: motor or batteries

Power switching transistors: MOSFETs

or IGBTs

From PWM

control circuit

Freewheel diodes

Filter capacitors

When power is applied to input, capacitors are charged up. When transistors are switched on, current flows from 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 motor’s magnetic field collapses to keep from increasing the voltage across the transistor to the point of failure.

Buying an EV

in the U.S.

Refer to Plug In America “Plug-in vehicle tracker”

Currently available EV’s in California:Tesla Roadster ($109,000)

EV’s 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 $50,000Toyota Rav4 (Tesla drivetrain) 2012 ?

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 EV’s 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 because

of limited public chargers

ELECTRICAL CAPACITY: 52.8 KWHR

CELL CAPACITY: 7.73 WHR (2.2 AMPHR)

QUANTITY OF CELLS: 6,831

CELLS 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

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)

TESLA TRANSMISSION

• Single speed fixed gear with electrically-actuated parking lock mechanism and mechanical lubrication pump

• Overall Final Drive 8.28:1

• Reverse direction of motor, limited to 15 mph

Tesla Battery Fabrication and Disposal

Lithium is the lightest naturally occurring element

Largest Producers are located in Chile (65% of world’s 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 Japan. The manufacturer complies with the “Directive on the Restriction of the Use of Certain Hazardous Substances 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