Special Report - VARTA PartnerNet UK

partnernet.varta.automotive.co.uk

Special Report - VARTA PartnerNet UK

Uwe Köhler and

Jörg Kümpers,

NBT GmbH, Hannover

Eberhard Meissner,

VB Autobatterie

GmbH, Hannover

Fig. 1:

NiMH Power Assist

Battery for hybrid

electric vehicles

(energy content:

2.8 kWh, maximum

discharge power:

55 kW)

Special

Report

High-Performance Batteries for

New Automotive Applications

1. Introduction

2. Development Trends in the Automotive

Industry

3. Requirements on Battery Systems

1 Introduction

Triggered by a variety of new applications in vehicles

of the future, battery manufacturers are

currently investing much activity in developments

aimed at meeting the growing technical

demands of vehicle manufacturers. These new

applications range from traction batteries for hybrid

electric vehicles (HEV) to new battery systems

for the 42V vehicle electrical power supply

systems of tomorrow. Interest in hybrid electric

vehicles has grown considerably, as pure electric

vehicles (EV) have failed to live up to

expectations. In addition to the limited range of

electric vehicles, the high costs of the large traction

batteries needed for EVs are also responsible

for their poor acceptance on the market.

1

4. Battery Systems for the Vehicles of

Tomorrow

– Lead-Acid Batteries

– Nickel - Metal Hydride Batteries

– Lithium-Ion Batteries

5. Summary and Outlook

6. Varta – The Battery Experts

7. References

Hybrid electric vehicles represent an interesting

compromise between an environmentallyfriendly

electric vehicle and a vehicle driven by

a combustion engine without range restrictions.

By lowering the fuel consumption and reducing

exhaust gas emissions, HEVs can make a significant

contribution to increasing the environmental

compatibility of automobiles.

Besides hybrid electric vehicles, there are a

variety of technical developments underway

that are aimed at improving the comfort, safety,

environmental compatibility and cost-effectiveness

of conventional vehicles through the

use of innovative electrical components. These


High-Performance Batteries for

New Automotive Applications

new vehicles can be expected to exhibit a growing

need for electrical performance and power

(Fig. 2). In order to meet these needs, the electrical

architecture of the vehicles will have to

change. Under discussion are dual-voltage

electrical systems (14V/42V), high-voltage electrical

systems, implementation of Integrated

Starter/Alternator and energy recovery devices.

These are aimed at boosting the efficiency of

producing, distributing, controlling and storing

of electrical energy within the vehicle.

Performances required for future electrical systems

Maximum Average

Application performance (W) performance (W)

Electrical wind shield heating 1,500 120

Electro mechanical valve actuation (EMVA) 1,800 - 3,400 700

Electro hydraulical valve actuation (EHVA) 400 200

Electrical cooling fan 650 50

Electrical water pump 600 100

Electrical power steering (servo) (EPS) 900 200

Electro mechanical brake 3,000 50

Wave stabilisator 2,000 150

Electrical fuel pump 450 150

Electrical A/C compressor 4,000 1,000

2 Development Trends in the Automotive Industry

The architecture of future energy supply systems

for vehicles will be determined by a number

of different factors.

Lower fuel consumption: The more efficient

use of fuel in vehicles is becoming increasingly

important, given the rising costs of fossil fuels,

stricter legislation governing emissions and regulations

aimed at cutting fleet fuel consumption.

The potential fuel savings in hybrid electric

vehicles can be as much as 50% compared to

conventional vehicles. Yet even in conventional

vehicles, significant improvements can be made.

Efficient fuel consumption in this situation is a

matter of generating, storing and using electrical

energy efficiently within the vehicle. The potential

savings can range from around 10% to

way above 20%.

2

Fig. 2: Future vehicle electrical supply systems

Power (kW)

5

4

3

2

1

0

1995 2000 2005 2010

New functions: There will be many components

requiring significantly higher voltages

than the normal 14V on offer today. For powerhungry

consumers such as electrically-heated

windows, DC converters for transforming to

higher voltages do not represent a cost-efficient

solution in the long term. Modern combustion

engines (especially diesel engines) also need

greater starting power. The subsequent shortening

of the starting routine that this allows

cuts emissions and reduces noise. Fast and

clean starting is a key requirement for the introduction

of start/stop systems, which contribute

significantly to saving fuel in urban traffic.

The recovery of braking energy and acceleration

assistance will need even higher power,

making increased operating voltages absolutely

essential.

Average power

performance IntegratedStarter/Alternators

with lead-acid

batteries (42V)

Average power

performance

conventional

alternators (14V)

Average power

demand of vehicle

electrical power

supply systems


Comfort features: With the introduction of

further comfort features, the overall demand for

electrical energy on board the vehicle will also

increase. A belt-driven system can currently

provide a maximum of 2 to 2.5 kW of electrical

energy. Because the power generated by the

alternator however is significantly less when

the engine is idle, extreme driving conditions in

urban traffic with lots of waiting can lead to insufficient

energy being available to supply the

new comfort features. This deficit needs to be

bridged with batteries.

Safety: In modern vehicles, only a limited number

of components that are critical for the

vehicle´s operation use electrical energy, e.g.

brake lights, airbag, ABS, ESP. This will change

with the new “drive-by-wire” technologies,

which include functions as steering, braking,

locks, etc. These systems will require additional

electrical energy, and in many cases at

relatively high levels, at least for short periods.

Besides technical advantages the changeover

from mechanically to electrically-driven systems

and components also offers the automotive

industry opportunities to lower production

costs and make better use of the available

space.

The new challenges facing battery systems

make it all the more important to be able to determine

the actual State of Charge (SOC) and

the State of Function (SOF). This applies just as

3 Requirements on Battery Systems

42V Vehicle Electrical Power

Supply Systems

With the introduction of new functions such

as the start/stop system, the technical demands

placed on the battery system are set to change

dramatically. Start/stop systems require fast,

quiet and low-emission vehicle startup, and

with a far greater frequency than is common

today. In addition to providing the electrical

energy for the starter system during startup,

the battery also has to supply power to all

consumers at times when the engine is switched

off. Under certain circumstances, this can

mean that the battery has to deliver a continuous

power of 1 kW for more than a minute.

After discharge, the combustion engine needs

3

much for hybrid concepts as it does for the

other on-board battery systems of the future,

and will have far-reaching consequences for the

battery industry. The battery will cease to be a

passive component, and will become a central

system component requiring monitoring and

management functions in order to safeguard

the vehicle´s functionality and safety.

to be restarted. The previously discharged

battery needs to be recharged as quickly as possible

before the vehicle comes to another standstill

and the engine is switched off again. Over

the life of the vehicle, tens of thousands of such

charge/discharge cycles can be expected. This

will increase the battery´s capacity throughput

by at least one order of magnitude compared

to the present situation.

The demands on battery discharge power

grow further if both the combustion engine

needs to be started and electrical acceleration

assistance (boosting) is used (approx. 10 kW

for a few seconds). In regenerative braking

(energy recovery), the recharge capability of the

battery needs to be of the same magnitude.

Fig. 3: The Battery

Management System

(BMS) will be part of

an intelligent electrical

supply system.

The BMS delivers

information about

State of Charge and

State of Function.


High-Performance Batteries for

New Automotive Applications

Fig. 5:

Varta 36V/42V VRLA-

AGM – battery for

application in advanced

vehicle

systems with high

power demand

Integrated starter/alternator systems of various

designs are under development for start/stop

systems, boosting and energy recovery systems.

The differences between these systems

are related to the type of electric motor used,

the transmission ratio to the crank shaft and the

arrangement of the clutch systems.

High-Voltage Systems for Hybrid

Electric Vehicles (HEVs)

The biggest motivation behind the development

of hybrid electric vehicles is the dramatic reduction

in fuel consumption and exhaust gas emissions.

HEVs, with their typical power assist and

energy recovery functions, generally work at

operating voltages in excess of 200V. The battery

capacity depends on the minimum requirements

for energy storage and electrical performance.

Virtually all hybrid electric vehicles use

relatively small batteries that have been designed

specifically for high discharge and

recharge performance. Pure electrical propulsion

has been abandoned in favor of high

power capabilities. The reduction in fuel consumption

is achieved by the optimized combination

of combustion engine and electrical propulsion

system, and by the recovery of braking

energy.

4 Battery Systems for the Vehicles of Tomorrow

Lead-acid batteries (Fig. 5), nickel - metal hydride

(NiMH) batteries and lithium-ion (Li-Ion)

batteries are all under discussion for use in the

vehicle electrical systems of the future. Nickelcadmium

(NiCd) batteries have very poor prospects

because of the same environmental con-

4

CIDI internal

combustion engine

5-speed manual transmission

& automated clutch Final drive

Integrated power electronics

Typical power requirements for HEV battery

systems vary from 20 kW to 60 kW. Because

of the enormous energy throughput, high demands

are placed on the long-term stability of

the battery system. These battery systems

need to provide sufficient power for the vehicle

to travel at least 200,000 km.

cerns that caused them to be ousted by NiMH

batteries in many portable battery applications.

High-temperature batteries such as sodiumsulfur

and sodium-nickel-chloride exhibit high

energy losses due to their very high internal

operating temperature, which can be tolerated

only in pure electric vehicles.

Supercapacitors capable of delivering extremely

high power are under development for applications

with extreme demands in terms of performance

and endurance. However, they exhibit

only low specific and volumetric energy densities,

and costs and weight of the power electronics

needed to manage the steep voltage

characteristics have so far seriously limited their

application.

Electrochemical storage systems, on the other

hand, deliver more energy at a more stable voltage

level. They can be designed either to deliver

a high power output or have a high energy

Battery

pack

Final drive

5-speed manual

transmission &

automated clutch

Electric machine

Fig. 4:

Energy recovered

during braking

can be reused for

acceleration

Picture:

DaimlerChrysler AG


Fig. 6: Specific data of different energy storage systems

Specific cold cranking

power (W/kg) 1)

80

60

40

20

300

200

100

Specific energy (Wh/kg) 2)

PAG

POB

AGM

Present demands are met by a standard

SLI battery of about 20 - 25 kg

• Cold cranking power: ~4 kW

• Energy content: ~1 kWh

• Energy throughput: ~100 kWh

PAG: Lead-calcium-silver technology

POB: Power-optimized battery

AGM: Absorptive glass mat

Li-Ion: Lithium-Ion

NiMH: Nickel - metal hydride

Li-Ion

storage capacity. Depending on the specific application,

the requirements on the energy and

the power density need to be harmonized, at

least in part.

Lead-Acid Batteries

Through technical modifications, e.g. reduced

electrode height, improved grid design and different

arrangement of the terminals, the performance

behavior of lead-acid batteries can be

significantly improved. This was realized, for example,

in the power-optimized battery (POB)

from VB Autobatterie. In this battery, only minimal

compromises are made in terms of specific

and volume-related energy values. The immobilization

of the electrolyte in an absorptive

glass mat (AGM) brings about major improvements

in the cycle life. While there is some reduction

in the specific energy, the volumetric

energy density remains virtually unchanged.

5

NiMH

10 200 500

Specific

energy

throughput

of battery

(kWh/kg) 3)

1) t = 3 sec., Umin > 22V, T = -18 °C

2) t = 20 h, T = 20 °C

3) within 3 - 4 years

Considerably higher power capability can be

achieved through the use of ultra-thin electrodes.

Because thin electrodes cannot be processed

individually, electrode pairs, separated

from each other by an absorptive glass mat, are

spiral-wound to form a coil. The improved performance,

however, is achieved at the expense

of the specific energy, the energy density and,

depending on the design, the endurance.

Figure 6 shows the three key parameters

specific energy (Wh/kg), specific cold cranking

power (W/kg) and specific energy throughput

(kWh/kg) of various lead systems, compared to

the alternative NiMH and Li-Ion systems. The

crucial advantage of the Lithium-Ion system is

its higher specific energy. The most prominent

feature of the NiMH system is its drastically

higher energy throughput.


High-Performance Batteries for

New Automotive Applications

Fig. 8:

Battery system

for use in a hybrid

electric bus (energy

content: 14 kWh,

power: 80 kW)

Nickel - Metal Hydride Batteries

(NiMH)

Of all the new battery systems, nickel - metal

hydride is regarded worldwide as the most technically

advanced. Therefore a large proportion of

new-generation electric vehicles introduced

into the market have already been equipped

with batteries of this type (e.g. Toyota RAV4, General

Motors EV1). But the market volume of

this battery types is still very small. In addition

to the actual NiMH high-energy cells which have

been developed to high specific energy levels

of approx. 80 Wh/kg, two product lines are of

interest for hybrid electric vehicles and the vehicle

electrical power supply systems of the future.

These product lines have been developed

specially for high power requirements (Fig. 7).

Power (P) Cells

A typical application scenario for NiMH power

cells would be the propulsion battery for conventional

hybrid electric vehicles, with a specific

range when used in purely electrical mode

(e.g. hybrid electric buses). High performance,

rapid-charging capabilities and a long service

life are all important for such applications. Due

to the relatively high capacity values (> 40 Ah)

resulting from the energy requirements, the

cells are produced in prismatic form. Even at

large capacities, this construction enables a relatively

large cell surface, which is required for

dissipating the waste heat generated during

battery operation.

6

Fig. 7:

NiMH-Product lines for high power requirements

Power(P)-Cells High-Power(HP)-Cells

60, 40 Ah 5, 8, 12 Ah

prismatic cylindric

< 60 Wh/kg < 45 Wh/kg

< 300 W/kg < 1300 W/kg (90% SOC)

The high requirements in terms of electrical

power are met at the expense of the specific

energy and energy density, which up to 60

Wh/kg and 150 Wh/l lie far below the level of

high-energy cells. However, the performance

during discharging and charging is significantly

better. Even when discharging with a 10minute

current (6 C rate), 85% of the stored

energy can be converted to useful energy. The

maximum specific power lies in the region of


Fig. 9:

NiMH-40V-battery for

new vehicle electrical

power supply

around 300 W/kg. Generally speaking, highpower

cells can be completely recharged within

around 60 minutes. Partial charging up to

around 80% is even possible within 10 minutes.

Rapid charging is limited by the temperature

rise within the cells, caused by the exothermic

formation of hydrides, and losses generated by

electrical resistance, as well as gas evolution at

the positive electrode in high states of charge.

High-Power (HP) Cells

High-power cells are the most important development

of the NiMH system. They have

been designed mainly for “Power-Assist” applications

in state-of-the-art hybrid electric vehicles,

where the improvement of energy efficiency

and the reduction of exhaust gas emissions

are at the forefront of the development

work. Their use in new 42V vehicle electrical

power supply systems is also very promising.

The NiMH system has been optimized specifically

for these applications to provide significantly

greater performance. HP cells are currently

available with capacities ranging from

5 Ah to 12 Ah. Because of their relatively low

capacities, these cells are produced in cylindrical

form. Positive and negative electrodes, separated

by a polymer fiber sheet, are spirally

wound. This process is inexpensive, and is currently

used to manufacture billions of portable

batteries.

HP cells can be continuously discharged at discharge

rates of up to approx. 40 C (1.5-minute

discharge) (Fig. 10). The full capacity is available

at a high voltage in excess of 0.9 V (approx.

80% of the open circuit voltage). The maximum

specific power output of HP cells can be up to

1,300 W/kg (Fig. 11). These cells can also be

charged from completely discharged state at

very high currents. At a charge rate of approx.

20 C, HP cells can be charged to approx. 80%

7

Fig. 10: NiMH-HP 5 Ah

Discharge characteristics

Voltage (V)

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0 1 2 3 4 5 6

Capacity (Ah)

Fig. 11: Energy power diagramm for different

NiMH cell design

Specific energy (Wh/kg)

75

50

25

5.5 A

27.5 A

55 A

82.5 A

110 A

165 A

220 A

0

0 250 500 750 1,000 1,250 1,500

Specific power (W/kg)

Power

High power


High-Performance Batteries for

New Automotive Applications

Fig. 12: Influence of DOD (depth of discharge)

on cycling endurance of NiMH cells

Capacity throughput

(Nominal capacity)

14,000

12,000

10,000

1)

2)

8,000

6,000

4,000

2,000

0

2,400

cycles

100%

1C/1C

5,000

cycles

80%

10C/10C

Depth of Discharge (DOD)

Charge/discharge rate

approx. 80,000

cycles

12%

18C/27C

> 300,000

cycles

5% 1)

2)

5C+2C/27C

SOC in less than 3 minutes. This corresponds

to a specific power absorption of approx. 1,200

W/kg.

A “Power-Assist” battery comprising 200 HP

round cells of 12 Ah nominal capacity is displayed

in Fig. 1. With a relatively low energy

content of 2.8 kWh, the maximum discharge

power at normal ambient temperatures is more

than 55 kW.

Fig. 9 shows the prototype of a NiMH battery

as may be used for a future 42V vehicle electrical

power supply system. The battery comprises

32 series-arranged individual cells, each

delivering a capacity of 12 Ah. With a system

weight of approx. 14 kg and an energy content

of approx. 500 Wh, the maximum electrical discharge

power at 20 °C is approx. 11 kW.

The service life – calculated in terms of either

calendar life or cycle life – is crucial for the costeffectiveness

of a battery system, particularly in

vehicle applications. The achievable capacity

throughput is mainly determined by the charging

and discharging conditions. Fig. 12 displays

the dominant influence of the depth of discharge

(DOD) on the attainable capacity throughputs

for NiMH systems tested under various

8

cycling conditions. Under a cycling regime with

one hour charging and one hour discharging at

100% DOD, the typical service life is 2,400 cycles

(reduction in capacity to 80% of the starting

value). If however the cells are run in a limited

SOC-window of 10% to 90%, the capacity

throughputs double. Operating the batteries

in a considerably smaller SOC-window (5%)

enables an extreme cycle life to be achieved

which corresponds to more than 14,000 times

the nominal capacity throughput. Internal resistance

and performance data remain virtually unchanged

in this cycling operation. This means

a consistent level of energy efficiency over the

battery´s entire lifetime.

Lithium-Ion Batteries (Li-Ion)

The tremendous weight advantage over other

battery systems makes the Li-Ion system a highly

attractive candidate for future energy storage

systems in vehicles with a particularly high demand

for electric energy. While NiMH highenergy

cells deliver specific energies of up to

80 Wh/kg, Li-Ion high-energy cells can deliver

approx. 130 Wh/kg, some 50% higher. The volumetric

energy density, at 270 Wh/l, lies approximately

20% above the density of equivalent

NiMH high-energy cells.

Current Li-Ion portable battery systems make

almost exclusive use of cobalt oxide for the

cathode material. However, this material cannot

be used in vehicle batteries due to its poor

availability and high costs. Battery manufacturers

are endeavoring to use cheaper materials

instead. In this regard, Varta has concentrated

on the lithium-manganese spinel.

Despite the tremendous technological advances,

the wide-scale use of Li-Ion batteries in

electric vehicles cannot yet be foreseen. This is

due firstly to the old problem of inadequate

energy density, as is also the case with other

battery systems. The other reason is that, even

when inexpensive materials are used, the price

for a battery with an energy storage capacity of

approx. 30 kWh is still prohibitively high. On the

other hand, smaller and higher-powered battery

systems are of great interest for 42V vehicle

electrical power supply systems and hybrid

electric vehicle applications. Similar to the NiMH

cell situation, there are two product lines that

are considered to offer the best opportunities

for the markets of the future (Fig. 13).


Fig. 13: Li-Ion-High-

Energy Cells with

40 or 60 Ah (prismatic)

and Li-Ion High

Power Cell with 6 Ah

High-Energy (HE) Cells

The main stimulus for the development of Li-Ion

high-energy cells is a dramatic improvement in

the storage of energy (in terms of weight and

volume) for supplying the vehicle electrical

power supply system. Vehicles equipped with

comfort features such as continuous air conditioning,

infotainment, will require electrical

energy storing devices of up to approx.

2 kWh. Because of their high specific energy,

Li-Ion batteries offer clear weight advantages

over today´s lead and NiMH high-energy batteries.

Were it to deliver the required storage

capacity of e.g. 2 kWh or so, the weight of a

lead battery would have to be around 50 kg,

while a high-energy NiMH battery would be approx.

30 kg. An equivalent Li-Ion battery would

weigh around 20 kg, not much more than a

modern lead starter battery. Fig. 16 shows a

Li-Ion high-energy battery (2.4 kWh) (operating

voltage: 40V) comprising 10 prismatic 60 Ah

cells.

High-Power (HP) Cells

While the high-power NiMH system has already

moved through the prototype stage and is

moving towards series production, a similar

development in terms of technology for Li-Ion

systems is still some way in the future. Nevertheless,

the results achieved to date have demonstrated

the enormous potential of this system

for the high-power sector.

9

Similar to the developments with NiMH, efforts

are being concentrated on relatively small cell

capacities in the range of 5 Ah to a maximum

of 10 Ah. The increase in power capability is

caused mainly by the use of thinner electrodes

and materials that are more able to carry high

currents. One fundamental problem is the conductivity

of the organic electrolyte, which is

around two orders of magnitude below that

of aqueous media. Similar to the high-performance

NiMH cells, the Li-Ion cells are manufactured

using a winding technology, for technical

and cost reasons.

Fig. 14 shows the voltage behavior of a Li-Ion

cell with a capacity of 6 Ah when it is discharged

with currents ranging from 6 A to

100 A. Even with a discharge current of 100 A

(approx. 16 C rate), voltages amounting to more

than 70% of the nominal voltage are observed.

The differences between the energy storage

and power behavior compared to an Li-Ion highenergy

battery can be seen in Fig. 15. While the

specific energy of an Li-Ion high-power cell of

55 Wh/kg is around half that of a high-energy

cell, its specific power is almost four times

higher at approx. 900 W/kg.

(cylindric) Fig. 14: Discharge characteristics of a

6 Ah Li-Ion High Power cell

Voltage (V)

4.2

4.0

3.8

3.6

3.4

3.2

3.0

2.8

2.6

2.4

0 1 2 3 4 5 6 7

Capacity (Ah)

2A

20A

35A

70A

100A


High-Performance Batteries for

New Automotive Applications

Fig. 15: Energy/power diagram (Ragone Plot)

for different Li-Ion cells

Specific Energy (Wh/kg)

125

100

75

50

25

0

0 250 500 750 1,000

Specific power (W/kg)

High energy cell

High power cell

Fig. 18:

Electrode belt manufacturing

for NiMH cells

The limited service life of Li-Ion batteries is still

their major weakness. It is currently determined

primarily by the drop in capacity over the

battery´s life. Depending on the size and type of

5 Summary and Outlook

The strengths of the existing lead-acid system

include high availability, low costs, an existing

recycling infrastructure and low self-discharge.

The system´s tolerance to limited overcharging

and deep discharging means only limited battery

management is required for existing applications.

The higher demands of future electri-

10

the cell, services lives of 2 to 4 years are standard

under normal ambient temperatures. This

is entirely adequate for most portable battery

applications, although in vehicle applications a

minimum service life of 5 years is required. The

advances that have been made in the stability

of the materials used have given rise to optimism

that this problem will be solved in the

foreseeable future.

cal power supply systems in vehicles, however,

make some battery management essential –

even for lead-acid batteries.

The results achieved with nickel - metal hydride

technology not only support their use in the hybrid

electric vehicles of tomorrow, but also open

up additional areas of application for new 42V

vehicle electrical power supply systems. With

specific power of approx. 1,000 W/kg, these

systems are in direct competition with capacitor

systems. At comparable performance values,

they offer an approximately 20 times higher

energy storage capacity. Particular strengths include

a high specific power and a high power

density, high capacity and energy throughput

and a long service life.

As far as applications in the vehicle sector are

concerned, lithium-ion technology still has some

way to go before it catches up with nickel -

metal hydride technology. The results achieved

so far, however, show that there is considerable

scope for technical enhancements. Specific

powers of up to 1500 W/kg at a specific energy

level of up to 80 Wh/kg would seem to be possible.

The main problem currently is the calendar

service life, especially under temperature

conditions that can be expected in automotive

applications.

Fig. 17: Li-Ion

High-Energy Module

(40V/60Ah)


Fig. 19:

Production of VRLA-

AGM batteries

6 Varta – The Battery Experts

VB Autobatterie GmbH is a joint-venture company

shared between VARTA AG and Robert-

Bosch GmbH, and has production sites in Germany,

Spain, France, Austria and the Czech

Republic, making it one of the largest manufacturers

of automotive batteries in Europe. Alongside

the ongoing further development of the

existing 12V (14V) lead-acid battery, VB is also

working on the development of the lead-acid

battery systems of tomorrow. This work mainly

involves AGM technology (AGM = Absorptive

Glass Mat) both for 12V (14V) and 36V (42V)

systems.

Batteries for new electrical power systems represent

a particular area of development focus.

These include various applications, such as the

upcoming 42V vehicle electrical system, multivoltage

vehicle electrical systems (14V/42V),

and separate systems for energy and power

storage. The spurs for these activities are the

rapidly-growing technical demands on electrical

performance in vehicles.

Varta Automotive’s NBT Technology Center focuses

on the development of new battery technologies.

These mainly include the nickel - metal

hydride and lithium-ion systems, which over

the last decade have become well established

in the portable battery industry and have superseded

other technologies (nickel-cadmium,

lead-acid) to a large extent in that field. Possible

areas of application for these technologies in

vehicles include 42V batteries for particularly

powerful vehicle electrical systems and supply

batteries for state-of-the-art, energy-saving and

11

ecofriendly hybrid vehicles. The features of

these new applications are high electrical performance

and the ability to deliver very highenergy

throughput over the vehicle’s service life.

The growing requirements of vehicle manufacturers

on battery system technology are being

met head-on through development activities focusing

on intelligent batteries. The aim is to develop

energy storage systems that use modern

electronics, for example, to determine their current

status in relation to readiness for operation,

state of charge, state of health, their remaining

service life and so on, to process this information

and to then forward it to the vehicle’s

electronic systems. VB Autobatterie and NBT

are both working closely with leading vehicle

manufacturers in these areas of research and

development.

Fig: 18:

Development of

Li-Ion cells

Fig. 20:

Electrode manufacturing

for NiMH cells


High-Performance Batteries for

New Automotive Applications

7 References

1. J. Kassakian Challenges of the New 42

Volt Architecture and Progress on its International

Acceptance; VDI Berichte No.

1415, p.21, VDI Verlag, Düsseldorf 1998

2. MIT Industry Consortium on Advanced

Automotive Electrical / Electronic Components

and Systems; c/o Massachusetts

Inst. of Technology, Laboratory for Electromagnetic

and Electronic Systems, 77

Massachusetts Ave., Cambridge, MA

02139

3. W. Buschhaus, A. K. Jaura, M. A.Tamor,

VDI Reports No. 1459, 1999

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Power Sources 67 (1997) 7

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John Wiley & Sons, New York, 1997

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Energy Storage and Conversion 2-Batteries,

Capacitors and Fuel Cells; Material

Research Society, Warrendale, 1998

Publisher: VARTA Aktiengesellschaft

Corporate Communications

Am Leineufer 51

D-30419 Hannover

12

7. M. Wakihara, O. Yasmamoto, Lithium Ion

Batteries, Wiley-VCH Verlag; Weinheim,

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Kluwer Academic / Plenum

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of Sixth International Seminar on

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Storage Devices, 1996

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J. Power Sources, 81-82 (1999) 585

Phone +49 5 11 79 03-8 21

Fax +49 5 11 79 03-7 17

E-mail: uwe.koehler@nbt.auto.varta.com

http://www.varta.com

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