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

EV101: Owning and Operating an Electric

Vehicle

Gary Graunke

Oregon Electric Vehicle Association(Oregon chapter of the Electric Auto Association)

December, 2007

Gratefully acknowledging many slides from

Steve HeckerothDirector of BIPV, ECD Ovonics

Chair Renewable Fuels and Sustainable Transportation Division

of the American Solar Energy Society

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• 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

Motor

Differential

SpeedPedal

MotorController

TractionBatteries

Charger

Contactors

Contactors

Aux.Battery

DC-DC

Just like a toy car, but high voltage and high current (danger!)

Throttle Linkage

Zap Throttle Linkage Converted Honda Insight Linkage

S10Electric PickupLinkage

Mechanical Input

Electric Output

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)

CafeElectric Zilla 1KContactors (ZAP)

Electricity is the only alternative fuel you can create when you go downhill

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

• 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

Agenda







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

• 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

• 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• 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

voltage

full 2.16V

empty 1.75V

voltage

full

empty

overcharge

Periodic rebalancing improves battery pack longevity

Capacity Variance with Aging

• 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 voltage

full

empty

overcharging

voltage

full 2.16

empty 1.75

Overdriving

0 volts

Check aging pack batteries for varying capacity

Use Appropriate Batteries

drive from downtown charge at aloha

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age

101(VDC)102(VDC)103(VDC)104(VDC)105(VDC)106(VDC)107(VDC)108(VDC)109(VDC)110(VDC)111(VDC)112(VDC)113(VDC)114(VDC)209(VDC)210(VDC)211(VDC)212(VDC)213(VDC)214(VDC)

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

Past Time for a New Pack

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101(VDC)102(VDC)103(VDC)104(VDC)105(VDC)106(VDC)107(VDC)108(VDC)109(VDC)110(VDC)111(VDC)112(VDC)113(VDC)114(VDC)209(VDC)210(VDC)211(VDC)212(VDC)213(VDC)214(VDC)

2V differences indicate exhausted or reversed cells

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• 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

Agenda







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

Agenda







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

Torque and mechanical power vs. rotation speed

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Shaft rotation speed, RPM

To

rqu

e (f

t/lb

s)

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(

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Max torque Rated torque Max power Rated power

Siemens 5105WS12 at 312 Volts

Insight torque 79 ft lbs at 1500 RPM Insight power 54.4 KW at 5700 RPM

Solar Powered Electric Vehicles

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.

The Clean Power/Transportation Solution

Almost Half a MWh of storage in the

parking lot

Photo courtesy Donald Aitkin

2 kW of PV per parking space

Agenda







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.

Vehicle Type$ Gas

25 Mi.

/Day

kWh 25 Mi.

/Day

$/year25 Mi. /Day

Gal/yr25 Mi.

/Day

Tons ofCO2/YrTailpipe

*+ Tons of UpstreamCO2/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

The real measure of efficiencyIt 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

Global Energy PotentialRenewables 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 5,000Energy Stored in the Earth

(Use it once and it’s gone)terawatt hours TOTAL

Coal 6,000,000Natural Gas (US Peak 2004) 1,500,000Uranium 235 (US Peak 2008) 1,500,000Petroleum (US Peak 1970, World Peak 2010) 1,000,000 Tar Sands 800,000

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

Agenda





• Sustainable transportation v.s. fossil fuels


Backup

The fossil fuel age on the scale of human history

Native Americans lived on this land for 12,000 years without diminishing its bounty

In 150 years of burning fossil fuel the Earths 3 billion year store of solar energy has been plundered

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

“ America is Addicted to Oil”

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.

US Oil Consumption

Will Peak 200?

World Peak Oil

Gray Area Shows the Range of Forecast Peak

Conventional Oil Reserves

Source Peak Date

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 < 2020

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

• 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

Fossil Fuel Dependence Solar Independence

Combustion Economy

Agrarian Economy

Solar/Electric Economy

combustion depletes stored energy resources, reduces the quality of essential resources and will cause conflict and economic collapse

Reliance on fossil energy has allowed population growth that can not be sustained by manual labor or beasts of burden

Moving toward reliance on clean energy from the sun will stabilize the quality of essential resources and allow positive evolution

QUALITY OF LIFE

FUSSIL FUEL USE

RENEWABLE ENERGY USE

Documents

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