Impact of Battery Characteristics on Fuel EEconomy 

AABCAABCMarch 2008

Aymeric Rousseau, Neeraj Shidore, y , j ,Richard Carlson, Dominik Karbowski

Argonne National Laboratory

Sponsored by Lee SlezakSponsored by Lee Slezak

This presentation does not contain any proprietary, confidential, or otherwise restricted information

Outline

Process Description

Optimum Control Strategy 

Impact of Available Energy

Impact of Peak Power

Impact of Temperature

– Battery in an emulated vehicle

– On‐Road vehicle testingg

Conclusions

2

Battery Characteristics Evaluation ProcessBattery Hardware

Vehicle Simulation

tJtSOCtP 11

Simulation

4WD Test Facility

tSOCtP nm ,

tJtSOCtP '0,000 ,1',1

tJtSOCtP MMMM ',' ,1,1

tU 0

tU M

TX 0X. . .

.

.

.

Emulated Vehicle

Global Optimization

Natural Cold Test Chamber

100% Modeling 100% Hardware

Energy & Power Temperature Effects

3

Global Optimization Allows Fair Comparison of Component Sizes and TechnologiesComponent Sizes and Technologies Knowing the drive cycle, the algorithm defines what would be the optimum component operating points to minimize fuelthe optimum component operating points to minimize fuel consumed. Algorithm adapts itself to all parameters influencing control: Drive cycle Distance Component size (energy, power) and technology…p ( gy, p ) gy

Impact of Energy Impact of Power

5 different AER (UDDS)Power remains constant

5 different powerEnergy remains constant

PSAT Vehicle Assumptions2.3L Ford

Duratec (100kW)5 SpdAMT

Ratio3.8

P195_60_R15Radius=0.317

Cd = 0.315FA = 2.244 m2

S ll SUV

Li-ionJCS

800W UQM75kW

Small SUVAll Electric Range of 5, 10, 20, 30 and 40 miles on UDDS

JCS41 Ah

72 cells61 kW (10s)

6 4 kWh usable

75kW Peak

5

6.4 kWh usable

Energy Sizing Impacts Fuel Displacement when Distance Traveled > AERwhen Distance Traveled > AER Distance Traveled  AER– Decrease in fuel consumption is proportional to increase in AER

1 5 L/100 km differen e bet een UDDS and LA92

6

7

100k

m)

Driven Distance: 10 miles

6

7

100k

m)

Driven Distance: 10 miles

300

350

(Wh/

km)

Driven Distance: 40 miles

Wh/km (UDDS)Wh/km (HWFET)

300

350

(Wh/

km)

Driven Distance: 40 miles

Wh/km (UDDS)Wh/km (HWFET)

– 1.5 L/100 km difference between UDDS and LA92

3

4

5

Cons

umpt

ion

(L/1

L/100km (UDDS)3

4

5

Cons

umpt

ion

(L/1

L/100km (UDDS) 150

200

250

Con

sum

ptio

n (Wh/km (HWFET)

Wh/km (LA92)

150

200

250

Con

sum

ptio

n (Wh/km (HWFET)

Wh/km (LA92)

0

1

2

Min

imal

Fue

l C L/100km (HWFET)L/100km (LA92)

0

1

2

Min

imal

Fue

l C L/100km (HWFET)L/100km (LA92)

0

50

100

Elec

tric

Ene

rgy

0

50

100

Elec

tric

Ene

rgy

6

05 10 20 30 40

AER (miles)

05 10 20 30 40

AER (miles)5 10 20 30 405 10 20 30 40

0

AER (miles)5 10 20 30 405 10 20 30 40

0

AER (miles)

Energy Impact on Battery use depends on Trip Distanceon Trip Distance

Distance Traveled  AER, 

Blended mode, 

120Driven Distance: 10 miles

120Driven Distance: 10 miles

120Driven Distance: 40 miles

120Driven Distance: 40 miles

Similar RMS current Lower RMS current

80

100

(A) 80

100

(A)

80

100

(A)

UDDSHWFETLA92

80

100

(A)

UDDSHWFETLA92

40

60

RM

S cu

rren

t

40

60

RM

S cu

rren

t

40

60R

MS

curr

ent

40

60R

MS

curr

ent

5 10 20 30 400

20UDDSHWFETLA92

5 10 20 30 400

20UDDSHWFETLA92

0

20

R

0

20

R

7

5 10 20 30 40AER (miles)

5 10 20 30 40AER (miles)

5 10 20 30 40AER (miles)

5 10 20 30 40AER (miles)

Peak Battery Power Has Little Influence on Fuel Consumptionon Fuel Consumption Lower fuel consumption for lower power levels due to decrease in regenerative 

braking energy

5

00km

)

250

Wh/

km)

Driven Distance: 10 miles5

00km

)

250

Wh/

km)

Driven Distance: 10 miles

g gy

3

4

mpt

ion

(L/1

0

150

200

umpt

ion

(W

L/100km (UDDS)

L/100k (HWFET)

Wh/km (UDDS)

Wh/k (HWFET)

3

4

mpt

ion

(L/1

0

150

200

umpt

ion

(W

L/100km (UDDS)

L/100k (HWFET)

Wh/km (UDDS)

Wh/k (HWFET)

2

Fuel

Con

sum

100

Ener

gy C

onsL/100km (HWFET)L/100km (LA92)

Wh/km (HWFET)Wh/km (LA92)

2

Fuel

Con

sum

100

Ener

gy C

onsL/100km (HWFET)L/100km (LA92)

Wh/km (HWFET)Wh/km (LA92)

0

1

Min

imal

0.6 0.8 1 1.2 1.40

50

Elec

tric

E

0

1

Min

imal

0.6 0.8 1 1.2 1.40

50

Elec

tric

E

8

0.6 0.8 1 1.2 1.4Power Scaling Ratio

0.6 0.8 1 1.2 1.4Power Scaling Ratio

Lower Power Leads to Higher Time Spent at High CurrentsSpent at High Currents

0.5

e

Driven Distance: 10 miles0.5

e

Driven Distance: 10 miles0.5e

Driven Distance: 20 miles0.5e

Driven Distance: 20 miles

0 3

0.4

the

Red

Zon

e

UDDSHWFETLA92

0 3

0.4

the

Red

Zon

e

UDDSHWFETLA92

0 3

0.4

n th

e R

ed Z

on UDDSHWFETLA92

0 3

0.4

n th

e R

ed Z

on UDDSHWFETLA92

0.2

0.3

age

of C

urri

n

0.2

0.3

age

of C

urri

n

0.2

0.3

tage

of C

urri

n

0.2

0.3

tage

of C

urri

n0.6 0.8 1 1.2 1.4

0

0.1

Perc

enta

0.6 0.8 1 1.2 1.40

0.1

Perc

enta

0.6 0.8 1 1.2 1.40

0.1

Perc

ent

P S li R ti0.6 0.8 1 1.2 1.4

0

0.1

Perc

ent

P S li R tiPower Scaling RatioPower Scaling Ratio Power Scaling RatioPower Scaling Ratio

Battery current is considered in the “red zone” when it exceeds the ti i l ( 150 A f f )

9

continuous maximum value (>150 Amps for reference)

Evaluation of Battery In An Emulated Vehicle SystemVehicle System

JCS VL41M260V, 41Ah

10

AER Decreases with Temperature

100

Initial Temperature 20 CVehicle Speed (m/s)

80

90

e speed

Initial Temperature 20 C Initial Temperature 0 CInitial Temperature -7 C

60

70

rge, Veh

icle

40

50

ate of Char

0 500 1000 1500 2000 2500 3000 350020

30Sta

11

Time (seconds)

AER Drops by 13% at -7C17 5

17.3417

17.5

16.5

DDS (m

iles)

9% Decrease 

13% Decrease

15.74

15.5

16

Range on

 UD

15 0615

15.5

EV R

15.06

14.5

‐10 ‐5 0 5 10 15 20 25

Initial Mod le Temperat re (De ree C)

12

Initial Module Temperature (Degree C)

AER Decrease Mostly Due to Regen Energy and Other Losses than Internal ResistanceOther Losses than Internal Resistance

Initial Temperature Battery kWh ΔkWh

Battery Losses at Lower Temperature

e pe u e

20 6.2 0

0 5.6 0.53

–7 5.5 0.73

SourceInitial

TemperatureΔWh compared to Wh

delivered at 20°CΔRegen Energy as

% of ΔWhΔI2Rt as % of

ΔWhΔOther Losses as

% of ΔW

0C 530 34% 8% 58%0C 530 34% 8% 58%

–7C 730 34% 12% 54%

13

Battery Temperature Impact During On Road TestingOn-Road Testing

315 VDC Li-Ion

20kW DC/DC

Hymotion/A123 7kWh Pack

Converter

Escape NiMH 340 VDC Battery Pack

Escape Powertrain

Inverter

Escape Powertrain

Hymotion Escape PHEVHymotion Escape PHEV7 kWh Li-ion (A123)

14

Fuel Economy Still Increases After 20 miles!miles!

Battery Temperature Still Increasing After

60 i t !

15

Entire Vehicle Was Cold 60 minutes!

Higher Li-ion Temperature Leads to Increased Battery Usage and Lower Fuel ConsumptionBattery Usage and Lower Fuel Consumption

16

Both Batteries Warmed – Cold Vehicle

Most of the Fuel Consumption Increase Due to Cold BatteryIncrease Due to Cold Battery

17

Percent increase in fuel consumption over steady-state fuel consumption –5°C

Impact of Cold Battery Mostly Due to Discharge EnergyDischarge Energy

18

Regenerative Braking Difference only Due to NiMH

Conclusion When the distance driven is higher than the AER, the optimal 

control is blended. As the engine is operated at high power, the battery RMS current is lowered.battery RMS current is lowered.

The available battery energy has significant impact on fuel consumption.

The peak battery power affects fuel consumption mostly with regard to regenerative braking energy.

The RMS battery current is influenced by several factors: The RMS battery current is influenced by several factors:

– Blended control lowers Irms

– Irms increases with electrical consumptionIrms increases with electrical consumption

Lower power batteries operate more often above their continuous current limits

19

Conclusion (cont’d)

Testing a battery in an emulated vehicle, the AER decreases by 9% at 0°C and by 13% at ‐7°C, as compared with 20°C conditions. Decreases in regenerative braking energy combined with “other losses” explain the changes.

For the PHEV conversion tested the on road test results For the PHEV conversion tested, the on‐road test results demonstrated that: 

– The powertrain warm‐up causes most of the losses during the early stage of the drive cycle (10 minutes)

– The battery pack then accounts for most of the changes in fuel consumptionconsumption

At cold temperatures, control limitations, especially discharging energy, are the main reason for lower fuel economy.

20

n1

Slide 20

n1 First bullet on this slide : Decreses in inherent battery capacity and regen energy explain the chagnes. ( There are the major contributors).nshidore, 4/27/2008