Battery Requirements and Cost

Analysis for Plug-In Hybrid Ve

Ahmad Pesaran

Tony Markel

National Renewable Energy Laboratory

Golden, CO, USA

ahmad_pesaran@nrel.gov, Tel: 303 275-4441

THE 24th INTERNATIONAL BATTERY SEMINAR & 

March 19 - 22, 2007

Fort Lauderdale, Florida

With funding from 

FreedomCAR and Vehicle Technologies Program

Office of Energy Efficiency and Renewable Energy NREL/PR-540-42082 U.S. Department of Energy 
2

Outline

• Why Plug-In Hybrids?• What is a Plug-In Hybrid?• Definitions and Terminologies• Current Plug-in Hybrid Convers• Battery Requirements• Analysis – Benefits and Costs• Summary
3

Why are Alternative Fuel and Ef

• Petroleum consumption has steadily increased

while domestic production has continued to decline

• Energy security and oil independence are 

major concerns in US

• World oil production will likely peak within the 

next 5-15 years

• Recent increase in gasoline price is an 

indicator of growing tension between supply and demand

• Greenhouse gas emission and global warming

concerns
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Why are Plug-In Hybrids 

• Most hybrid vehicles still consume petroleum• Alternative fuel vehicles such as E85 are ava

and required infrastructure are not ready.

• Mass production of hydrogen fuel cell vehicle

the next 15 years. 

• Electric vehicles are not likely to be mass pro

next 20 years due to battery cost, charging ticharging infrastructure requirements.

• Plug in hybrids offer potential for both energy 

use of domestic energy (electricity) without pnew fueling infrastructure.

• A majority of US drivers travel fewer than 40 

vehicle with short EV range and long petroleattractive.

• The President’s State of Union Address in 20
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Plug-in Hybrid Stakehold

R

U

US Gov./DOE

Reduced petroleum use;

Use alternative energy

Auto Manufacturers

Sell cars

Electric U

Sell elect

Battery Manufacturers

Sell batteries

Consumers

Drive affordable

functional, fun, and 

feel good cars 

Security advocates, Environmentalists, Co

Conversion companies, Component su
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What is a Plug-In Hybrid 

An HEV with an energy storage system that c

ADVANCED ENGINE

ENGI

ENGINE DOWNSIZING

REGENERATIVE BRAKING

ELECTRICITY

PETROLEUM

AND/OR

Fuel Flexibility
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Some PHE

Charge-Depleting (CD) HEV Mode: Vehicle operation o

engine subsystem or both with a net decrease in batter

Charge-Sustaining (CS) HEV Mode: Vehicle operation 

engine subsystem or both at ‘relatively constant’ battery (i.e. within a narrow range).

All-Electric Range (AER): After a full recharge, the total 

electrically (engine-off) before the engine turns on for th

Charge-Depleting Range (CDR): After a full recharge, t

before the vehicle reaches charge-sustaining mode.

PHEV20: A PHEV with useable energy storage equivalen

driving energy on a reference driving cycle. A PHEV20 petroleum energy equivalent to 20 miles of driving on thwith off-board electricity.

NOTE: PHEV20 does not imply that the vehicle will achie

or CDR on the reference cycle nor any other driving cycharacteristics also depend on the power ratings of compowertrain control strategy and the nature of the driving 
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Operating St

All-Elect

• Engine turns on when power 

exceeds battery power capability

• Engine only provides load that 

exceeds battery power capability

• Engine is o

electric ran

• Engine tur

reaches lo

• Requires h

and motor

Charge Depleting Electric

Charge Deple
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How Do PHEVs Redu

C

Distance

Consumption

Conventional V

Hybrid Vehicle

Charge-Depleting Mode Charg

Plug-In Hybrid V

PHEV Benefits

Efficiency in Charge-Sustaining Mode

Petroleum Displacement in Charge-Depleting Mode

Consumption Benefits of PHEV Technology Tied to Usage Pattern

~10-35%~50-80%
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Some of PHE

EnergyCS Plug-In Prius Hymotion Escape PHEV

AC Propulsion Jetta PHEV

A

R

DaimlerChrysler Sprinter Van PHEV
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Batteries in Cu

Johnson Controls / SAFT

Valence Technology

A

Electr

NiMH Co/Ni based

Li-Ion

Iron phosphate 

based Li-Ion

Johnson Controls / Varta
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Battery Usage in EVs, HEVs

CS: Charge Sustaining *Battery capacity for 

CD: Charge Depleting

U

Charged and 

used (CD)

Charged capacity, 

not used

Charged and 

used (CD)

Used frequently in CS

Used sometimes in CS

Charged, not 

used

Charged, not used
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4000

50%70%

Battery Cycle Life Depends on 

• PHEV battery likely to deep-cycle each day driven: 15 yrs equates to • Also need to consider combination of high and low frequency cycling

Source: Christian Rosenkranz (Johnson Controls) at EVS 20, Long Beach, CA, Novem

Need to 

for state
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Battery Sizin

EV range, vehicle (mass, aerodynamic, etc.), 

kWh/mi

(from simulation)SOC windowEqui EV rangekWmotor(from simulation)Performance constraints

kWh usable

kWh total

P/EkWengine

DOH

Tot

mass compounding

DOH = degree of hybridization

Source: Tony Markel and Andrew Simpson, Milestone Report, National Renewable EneGolden, CO, September 2005. 
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Example of Battery Requirem

1. These categories are similar to the ones proposed for USABC charge-deple

FreedomCAR charge-depleting power-assist HEVs

2. Typical numbers, final USABC numbers could be found in 

http://www.uscar.org/commands/files_download.php?files_id=11

1 
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KEY BENEFITS

Consumer:

• Lower “fuel” costs• Fewer fill-ups• Home recharging convenience• Fuel flexibility

Nation:

• Less petroleum use• Less greenhouse and 

regulated emissions

• Energy diversity/security

PHEV Key Benefits an

Cost-Be

KEY CHAL• Energy S

– Cos– Life 

• • 

– Saf– Pac– The

• Power Ele• Vehicle co
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Predicted fuel economy and operating costs for mid

1) Assumes 15,000 miles annually, gasoline price of $2.40 per gallon, 2) Note that average US household consumes 10,700 kWh of electricit

3) Using 110V, 20A household outlet

Plug-In Hybrid F

Vehicle Type Gasoline 

Fuel 

Economy

Electricity 

Use

Annual 

Energy Use

Conventional 27 mpg --- 564 gal. Hybrid-Electric 36 mpg --- 416 gal. Plug-In Hybrid20mi range

51 mpg 0.09 kWh/mi 297 gal. and 

1394 kWh2

$7

Plug-In Hybrid40mi range

69 mpg 0.16 kWh/mi 218 gal. and 

2342 kWh2

$5
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Powertrain Costs Compariso

UDDS AER 

From A. Simpson and T. Markel, 22nd Electric Vehicle Symposium, Y
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Long-term scenarioLI-ION BATTERIES

$3.00/gal. $0.09¢/kWh (2005 average, not off-p

Payback time of PHEVs Relative to H

the initial battery co

Maintenance costs not included, no discount ra

From A. Simpson and T. Markel, 22nd Electric Vehicle Symposium, Yok
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Long-term scenarioLI-ION BATTERIES

Both Higher Gas Prices and Low

Required for PHEV to Payback 

Maintenance costs not included, no discount rate a

$5.00/gal. (future?)

$0.09¢/kWh (2005 average, not off-peak)

From A. Simpson and T. Markel, 22nd Electric Vehicle Symposium, Yok

Ib
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Concerns with Battery Pa
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Conclud

• PHEVs could displace petroleum consumption w

renewable electricity.

• Batteries with low power to energy ratios are ne• Widening of the battery’s usable SOC window w

life will be critical for reducing system cost and vdecrease the life.

• A blended operating strategy as opposed to an 

focused strategy may provide some benefit in revolume while maintaining petroleum consumptio

• Battery requirements for PHEVs are demanding

operation, wide SOC operation, both shallow an

• PHEVs make economic sense with lower batter

gasoline prices, otherwise other incentives or ta

• The key barriers to commercialization of PHEVs 

packaging, safety, and cost.