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Contract No. DE-AC36-08GO28308

USABC Development of 12 Volt 

Battery for Start-Stop 

Application

Preprint

Harshad Tataria

General Motors Company 

Oliver Gross

Chrysler Group LLC 

Chulheung Bae

Ford Motor Company

Brian Cunningham and James A. Barnes

U.S. Department of Energy

Jack Deppe

Deppe Consulting LLC

Jeremy Neubauer

National Renewable Energy Laboratory 

Presented at EVS27 International Battery, Hybrid and Fuel Cell Electric 

Vehicle Symposium

Barcelona, Spain

November 17–20, 2013

Conference Paper

NREL/CP-5400-62680

February 2015
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EVS27

Barcelona, Spain, November 17-20, 2013

USABC Development of 12 Volt Battery for Start-Stop 

Application

Harshad Tataria1, Oliver Gross2, Chulheung Bae3, Brian Cunningham4, James A. Barnes4, 

Jack Deppe6, Jeremy Neubauer5

1Corresponding Author harshad.s.tataria@gm.com, Tel: 248-836-7894, Fax: 586-492-4420, General Motors

Company, Warren, MI, USA 2

Chrysler Group LLC, Auburn Hills, MI, USA 3

Ford Motor Company, Dearborn, MI, USA 4

U.S. Department of Energy, Washington, DC, USA 5

National Renewable Energy Lab, Golden, CO USA 6 Deppe Consulting LLC , Davidsonville MD, USA

Abstract

Global automakers are accelerating the development of fuel efficient vehicles, as a part of meeting regional

regulatory CO2 emissions requirements. The micro hybrid vehicles with auto start-stop functionality are 

considered economical solutions for the stringent European regulations. Flooded lead acid batteries were 

initially considered the most economical solution for idle-stop systems. However, the dynamic charge 

acceptance (DCA) at lower state-of-charge (SOC) was limiting the life of the batteries. While improved 

lead-acid batteries with AGM and VRLA features have improved battery longevity, they do not last the life 

of the vehicle. The United States Advanced Battery Consortium (or USABC, a consortium of GM, Ford, 

and Chrysler) analyzed energy storage needs for a micro hybrid automobile with start-stop capability, and

with a single power source. USABC has analyzed the start-stop behaviors of many drivers and has 

developed the requirements for the start-stop batteries (Table 3). The testing procedures to validate the 

performance and longevity were standardized and published. The guideline for the cost estimates 

calculations have also been provided, in order to determine the value of the newly developed modules. The 

analysis effort resulted in a set of requirements which will help the battery manufacturers to develop a 

module to meet the automotive Original Equipment Manufacturers (OEM) micro hybrid vehicle 

requirements. Battery developers were invited to submit development proposals and two proposals were 

selected for 50% cost share with USABC/DOE.

Keywords: HEV, Micro Hybrid, 12 V Start-Stop, Batteries
2

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1 USABC Introduction

Mission: To develop electrochemical energy 

storage technologies which support 

commercialization of fuel cell, hybrid, and 

electric vehicles. 

Strategic Vision: The USABC seeks to promote 

long-term R&D within the domestic 

electrochemical energy storage (EES) industry 

and to maintain a consortium that engages 

automobile manufacturers, EES manufacturers, 

the National Laboratories, universities, and other 

key stakeholders.

Objectives: For high-energy and high power 

energy storage technologies and models, the 

USABC shall continue its focus on 

understanding and addressing the following 

activities:

• Continue development of high-power 

battery technologies to reduce cost to $20/kW 

and extend life to 15 years. 

• Develop battery technology to support 

electric, hybrid and fuel cell vehicles. 

• Develop ultracapacitor technology for 

hybrid electric vehicle applications. 

• Conduct benchmarking activities for 

both high power and high energy batteries and 

ultracapacitors to validate technologies. 

• Publish technical goals and associated 

test procedures to guide the development of 

electrochemical energy storage systems. 

2. Start-Stop Battery 

Introduction

While HEVs (mild, moderate, and strong) and 

PHEVs can achieve significant improvements in 

CO2 emissions of individual vehicles, start-stop 

and micro hybrid technology can greatly reduce 

the cumulative vehicle fleet CO2 emissions and 

improve fuel economy with a minimum increase 

in vehicle cost of hybridization. It is estimated 

that more than 16 million vehicles in North 

America and 80 million vehicles globally will be 

produced annually. Widespread adoption of 

HEVs which shuts the engine off during idle is 

already underway in Europe and Asia. It is 

expected that, by 2017 in excess of 70% of all 

vehicles manufactured in North America will 

include start-stop functions.

USABC has been developing the HEV, PHEV, 

and EV batteries and ultracapacitor energy 

systems for more than 20 years with the help of 

U.S. Department of Energy (DOE). The USABC 

has identified the need for a start-stop technology

which will be cost competitive with current 

batteries, e.g. Pb-Acid, NiMH, and Li-Ion. With 

the help of the National Renewable Energy 

Laboratory (NREL) modeling and simulation 

capability, the USABC has developed start-stop 

energy storage technology requirements (Table 

3). This paper presents the analysis and vehicle 

data – actual and simulation - used to determine 

these requirements. The size, weight and cost 

were also estimated to complete the 

requirements.

3. Vehicle and Data Analysis

The strategy for the battery requirements and 

module development was to build a simplified 

model for a mid-size vehicle and apply realworld drive data to characterize start-stop energy 

storage system requirements and potential 

benefits. Drive data from a large number of 

vehicles / drivers in three cities – Austin and San 

Antonio, Texas [1] and Los Angeles, California [7]

in the USA, was utilized for this purpose. It 

consisted of 1,984 vehicle days of second-bysecond vehicle speed histories. Figures 1 and 2 

show the respective frequency distribution of 

engine start events observed in this data set, per 

day and per mile, assuming each vehicle is 

equipped with a start-stop system. For the 95th

percentile driver, this corresponds to 73 start 

events per day (3.5 starts per mile).

Figure 1: Number of Vehicle 

Starts/Day Frequency Distribution
3

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Figure 2: Number of Starts/Mile Frequency 

Distribution

The datasets employed did not contain 

information on the state of the vehicle ignition 

(i.e. whether the ignition was “on” or “off”). It 

was therefore assumed that any stop shorter than 

2.5 minutes was a key-on stop (where the startstop energy storage system must sustain the 

auxiliarly loads of the vehicle over the duration 

of the stop), and any stop greater than 2.5 

minutes was a key-off stop. Given the 95% of 

all stops are less than 2.5 minutes in duration 

(figure 3), this assumption will capture the 

majority of stop events in the data as key-on 

events..

Figure 3: Maximum Stop Duration Frequency 

Distribution

A simplified vehicle model was run for each of 

the available vehicle speed histories. A nominal 

alternator load on an idle vehicle has been set to 

60A and 12.5V = 750W. This model calculated 

the energy storage system state of charge (SOC) 

as a function of time assuming that 750 W of 

power is available to charge the battery when the 

vehicle is driving, and that it is discharged at a 

rate of 750 W when stopped in the key-on state. 

1.7 Wh was assumed to be discharged for every 

start event. An annotated example for a single 

vehicle is shown in Figure 4. A key output of 

this simulation is the required amount of energy a 

start-stop system must make available to sustain 

start-stop operation during a day of real-world 

driving, shown in Figure 5. 

Figure 4: Example Energy Storage System 

Simulation Result

Figure 5: Total Energy Required Frequency 

Distribution

The data in Figure 5 suggests that the median 

required energy for start-stop functionality is 21 

Wh, and that 56 Wh is necessary to cover the 95th

percentile driver. To determine the minimum 

energy content of the energy storage system this

value was added for the 95th percentile driver to 

the critical loads of cranking the engine, reserve 

needed for parasitic loads during long term 

parking, emergency hazard flasher and the 

accessory loads (Table 1). The energy needed for 

climate control were not included assuming the 
4

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engine may not turn off if the need for climate 

control is sensed. The total energy needed is 

conservatively estimated to be about 360Wh and 

is labeled available energy to support the listed 

loads.

Table 1: Energy Estimation

Load Req’d 

Energy

Req’d 

Power

Start-Stop

(95th percentile)

56 Wh ~6 kW

Cold Start Reserve 9.2 Wh ~6 kW

High Accessory Load 

(12 min)

150 Wh 750 W

Parasitic Load 

(15 mA for 30 days)

130 Wh n/a

Energy throughput on a per mile basis is also 

useful, as presented in Figure 6.

Figure 6: Energy Delivered/Mile by the Battery 

Frequency Distribution

This same model was also employed to calculate 

the potential fuel savings of a start stop system. 

Here the idle fuel rate of a vehicle without a 

start-stop system is assumed to be 0.28 g/s, and 

that the overall efficiency of the engine and 

alternator is 22% when recharging. Results of 

this analysis (Figure 7) show that the median 

annual fuel savings is ~7.5 gallons per year. 

However the 95th percentile driver can save 29 

gallons per year. This corresponds to a total fuel 

savings of 2 to 6%, which agrees well with the 

urban dynamometer driving schedule (UDDS) 

test cycle results reported in the reference[6].

Figure 7: Annual Fuel Saving Frequency 

Distribution

Using the median annual fuel savings and the 

U.S. Energy Information Administration (EIA)

2011 high-oil price scenario gas price forecast 

(~$5/gallon on average between 2015 and 2030) 

[5], one can calculate the total fuel savings in 

dollars per vehicle. Conservatively assuming a 

10% discount rate and 2.5% inflation rate, the 

present value of the fuel savings offered by a 

start-stop system to the driver is approximately 

$384. Note that the cost of the system to the 

OEM must be considerably lower than this to 

account for markup factors and competitive 

market factors.

An ALABC study [4] computed CO2 reductions 

for a similar start-stop system (Table 2), 

reporting 6-8% reductions. While CO2 savings 

were not directly computed in this analysis, the 

ALABC numbers are in line with the 95th

percentile driver when it is assumed that CO2

savings are proportional to fuel savings. 

Table 2: ALABC Study [4]

Metric Micro-Hybrid

Battery Voltage (V) 12

Regen. Power (kW) 0.5-3.0

OEM On-cost ($) 200-900

CO2 Emission 

Reduction (%)

6-8

Cost / Benefit

($ / % CO2 reduction)

50-130
5

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4. Life-cycle Test Based on Study

Findings: 

4.1 Life Cycle Testing [2]

The most common test (SBA S 0101:2006 

derived by Japan SAE), was studied. The test

was standardized to determine the cycle life for 

Pb-Acid batteries for vehicles with idling-stop 

systems. The procedure is outlined in Figure 8.

Figure 8: SBA Testing Profile

Since the USABC was looking for a 12 Volt 

battery which would last the life of vehicle and 

be maintenance free, the procedure was revised 

to comply with the features of advanced 

batteries (e.g. Li-Ion using a charge neutral 

profile to maintain the target SOC (State of 

Charge)) (Figure 9).

Figure 9: 12 Volt Start-Stop Cycle Life Test 

Profile

4.2 Cold-Cranking Profile:

Cold cranking power analysis, shown in Figure 

10 included the battery data for a cold crank for a 

Class 1, 3⁄4 ton pickup truck (5.3 L V-8 engine, 

automatic transmission, 5W30 oil). The cold 

cranking profile was simplified for testing based 

on the original testing results, and defined for -

30°C.

Figure 10: Original Cold Cranking Profile

The simplified profile is as shown below, in 

Figure 11.

Figure 11: Simplified Cold Cranking Profile

5. Vehicle 

A 12 Volt vehicle electric and electronic system 

is considered for these battery requirements. The 

cost/benefit ratio for a 12 V system operating 

only in a stop-start mode was also considered

from a business-study point of view. The regen 

capability of the vehicle during the vehicle 

deceleration was not considered for an optimum 

vehicle and battery cost/benefit ratio. There are 

vehicles in the field operating with this type of 

configuration. The battery in a conventional ICE 

vehicle is charged by the alternator at 50-60 A. It 

was assumed that start-stop battery will be 

charged whenever there is an opportunity and it 

was not planned to regen at very high currents. 

Also there was no power assist expected during 

the launching of vehicle after an auto start. Cabin 

climate control during auto stop was expected to 

be limited, so the auxiliary loads do not include 

the cabin climate control.

The auto-start-stop function switches off the ICE 

engine automatically when the vehicle is stopped 
6

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at a traffic light or traffic jam, etc. The function 

also starts the engine automatically on driver’s 

demand. The battery is maintained at a desired 

state of charge (SOC) by using the opportunity 

charging available from the alternator. The fuel 

not used during the auto stops thus improves the 

fuel economy and reduces the total CO2 

emissions.

The estimated fuel saving and CO2 emissions are 

reported in Figure 7 and Table 2.

The battery voltage is very critical for the vehicle 

load maintenance. If the battery voltage is too 

low and the engine is cranked the high current 

draw by the starter motor induces a large 

transient voltage disturbance on the electrical 

system. The auxiliary electrical load performance 

is noticeably affected by the changes of electrical 

system voltage during the auto stop, and the 

customer may sense a performance quality 

impact during the engine restart. The target SOC 

therefore must be kept high without sacrificing 

the life of the battery.

6. Battery Technology

Two present battery technologies appear well 

suited to the needs of start-stop systems:

Advanced Lead-Acid Batteries: AGM batteries 

have demonstrated a longer life than 

conventional Start Light Ignition (SLI) batteries. 

According to ALABC the Lead-Carbon (PbC) 

UltraBattery may have a longer life.

Li-Ion Batteries: USABC has been developing 

Li-Ion batteries with graphite anodes for various

hybrid and EV applications. The life testing of 

these batteries estimate that the batteries will last 

the life of the vehicles in HEV, PHEV, and EV 

applications. The 12 V start-stop batteries will be 

stressed by repeated starting and may not have 

sufficient power for a cold-cranking operation. 

The new development of a Lithium Titanium 

Oxide (LTO) anode may solve these problems. 

USABC is providing funding to develop the 

following couples for commercialization of 12 

Start-Stop batteries in near future. 

NMC/LTO Couple: 5 cells in series show 

an excellent match to meet USABC voltage 

requirements. 

LMO/LTO Couple: 5 Cells in series will 

provide the maximum and minimum voltage 

to match 6 cells in series combination with 

Lead-Acid batteries. The rate capability and 

low temperature performance is expected to 

match the requirements in Table 3.

7. Conclusion

The hybrid vehicles with lowest level of 

hybridization are growing worldwide. There will 

be some vehicles with micro hybrid and mild 

hybrid capability in some countries, however the 

most economical application will be with startstop. This will increase the fuel economy and 

lower CO2 emissions

Li-Ion batteries are the dominant and most 

promising battery technology for the most 

economical single 12V battery solution and it 

will have the potential to last the life of the 

vehicle. The Li-Ion battery technology will 

reduce the weight and volume of the battery and 

reduce the life cycle cost when compared with 

the conventional lead-acid battery solution. The 

estimated cost of the USABC specified battery is 

challenging. However, the response from the LiIon battery developers shows that the LTO anode 

may provide the desired cost, life, and durability. 

Currently USABC has awarded two contracts to 

develop and deliver the batteries to DOE national 

labs for verification.

Acknowledgments

The U.S. Department of Energy (DOE) Office of 

the Vehicle Technology Office supported this 

effort. We appreciate the technical guidance 

provided by the USABC Technical Advisory 

Committee (TAC) and Management Committee 

(MC).
7

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References

[1] 2006 AUSTIN/SAN ANTONIO GPSENHANCED HOUSEHOLD TRAVEL 

SURVEY, TECHNICAL SUMMARY by

Mark Ojah, Assistant Research Specialist, 

Texas Transportation Institute and David F. 

Pearson, Ph.D., P.E., Program Manager, 

Transportation Planning, Texas 

Transportation Institute, August 2008

[2] SBA S 0101:2006 Lead-Acid Batteries 

for Vehicles with Idling-Stop Systems

[3] Battery Test Manual For 12 Volt StartStop Vehicles,

http://www.uscar.org/guest/article_view.php

?articles_id=86

[4] ALABC 2013-2015 Prospectus

[5] 

http://www.eia.gov/dnav/pet/hist/LeafHandle

r.ashx?n=PET&s=EMM_EPMR_PTE_NUS

_DPG&f=W [Accessed: June 5, 2012].

[6] Lohse-Busch, Henning, et. al, 

“APRF/AVTA Idle Stop Vehicle Testing,” 

http://www.transportation.anl.gov/D3/reports

/ANL_APRF_IdleStopvehicleStudy_August

2011.pdf [Accessed: June 25, 2013]

[7] Year 2000 Post-Census Regional Travel 

Survey: Final Report of Survey Results, 

Southern California Association of 

Governments, Fall 2003.

Authors

Mr. Harshad Tataria, Manager, 

Technical Advisory Committee, 

USABC and Tech Team, USDRIVE is 

a Staff Project Engineer at General 

Motors Corp, Mr. Tataria has over 40 

years of experience in battery 

development. He has obtained 5 

patents and published 34 papers in 

various scientific journals. In 2013 he 

was awarded Life Time Achievement 

Award by USCAR for his leadership 

and commitment to USCAR.

Mr. Oliver Gross, Manager, Technical 

Advisory Committee, USABC and 

Tech Team, USDRIVE is a Senior 

Energy Storage Systems Specialist at 

Chrysler Group, Mr. Gross has over 20 

years of experience in battery 

development and manufacturing. His 

experience includes Lead-Acid, 

NiMH, Li metal primary and 

secondary, and Li-Ion batteries. He 

has obtained 9 patents and published 

21 papers in various scientific 

journals, as well as frequent 

conference presentations and seminars. 

Dr. Jeremy Neubauer is a Senior 

Engineer with NREL’s Center for 

Transportation Technologies and 

Systems, where his research activities 

focus on lifetime analysis of batteries 

and optimizing battery use strategies 

for automotive and grid applications. 

Dr. Neubauer has a Bachelors, 

Masters, and Doctorate in Mechanical 

Engineering from Washington 

University in St. Louis.

Dr. Chulheung Bae, Manager, 

Technical Advisory Committee, 

USABC is a battery cell development 

engineer at Ford Motor Company. 

Dr. Bae has over 16 years of 

experience in battery research and 

development for various applications. 

He has obtained 4 patents and 

published 11 papers in various 

scientific journals

Mr. Brian Cunningham, Manager, 

Technical Advisory Committee, 

USABC is a Technology Development 

Manager at the United States 

Department of Energy’s Vehicle 

Technologies Office. Mr. 

Cunningham has over 3 years of 

experience in battery research and 

development
8

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Dr. James A. Barnes, Manager, 

Technical Advisory Committee, 

USABC is a Research Chemist on 

assignment to the United States 

Department of Energy’s Vehicle 

Technologies Office. He has over 30 

years of experience in battery 

research and development and has 

written a wide range of technical and 

review presentations.

Dr. Jack Deppe is a member of the 

USABC Technical Advisory 

Committee and the USDrive, and works 

closely with the DOE energy storage 

national laboratory programs. His 

concentration is in energy storage for 

automobiles with 20 years of 

experience in energy storage and 

electrochemistry, with concentrations in 

ionic conduction, materials research, 

ultracapacitors, and modeling.

Table 3: USABC Goals for Advanced Batteries for 12V Start-Stop Vehicle Applications [3]

End of Life Characteristics Units

Target

Under hood Not under 

hood

Discharge Pulse, 1s kW 6

Max current, 0.5s A 900

Engine-off accessory load W 750

Cold cranking power at -30 °C (three 4.5-s pulses, 

10s rests between pulses at lower SOC)

kW 6 kW for 0.5s followed by 4 kW 

for 4s

Extended Stand Test (30 days at 30°C followed by 

cold crank test)

kW 6 kW for 0.5s followed by 4 kW 

for 4s

Min voltage under cold crank Vdc 8.0

Available energy (750W) Wh 360

Peak Recharge Rate, 10s kW 2.2

Sustained Recharge Rate W 750

Cycle life, every 10% life RPT with cold crank at 

min SOC

Engine 

starts/miles

450k Starts /150k Miles

Calendar Life at 30°C, 45°C if under hood Years 15 at 45°C 15 at 30°C

Minimum round trip energy efficiency % 95

Maximum allowable self-discharge rate Wh/day 10

Peak Operating Voltage, 10s Vdc 15.0

Sustained Max. Operating Voltage Vdc 14.6

Minimum Operating Voltage under load Vdc 10.5

Operating Temperature Range (available energy to 

allow 6 kW (1s) pulse)

°C -30 to + 75 -30 to +52 

30 °C – 52 °C % 100 (to 75°C) 100 

0 °C % 50

-10 °C % 30

-20 °C % 15

-30 °C % 10

Survival Temperature Range (24 hours) °C -46 to +100 -46 to +66

Maximum System Weight kg 10

Maximum System Volume L 7

Maximum System Selling Price (@100k 

units/year)

$ $220 $180