JUST I C E National Institute of Justice

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U.S. Department of Justice

Office of Justice Programs

National Institute of Justice

National Institute of JusticeLaw Enforcement and Corrections Standards and Testing Program

NEW TECHNOLOGY BATTERIES GUIDE

NIJ Guide 200-98

The National Institute of Justice is a component of the Office of JusticePrograms, which also includes the Bureau of Justice Assistance, Bureau ofJustice Statistics, Office of Juvenile Justice and Delinquency Prevention, andthe Office for Victims of Crime.

ABOUT THE LAW ENFORCEMENT AND CORRECTIONS STANDARDS AND TESTING PROGRAM

The Law Enforcement and Corrections Standards and Testing Program is sponsored by the Office of Science andTechnology of the National Institute of Justice (NIJ), U.S. Department of Justice. The program responds to the mandateof the Justice System Improvement Act of 1979, which created NIJ and directed it to encourage research anddevelopment to improve the criminal justice system and to disseminate the results to Federal, State, and local agencies.

The Law Enforcement and Corrections Standards and Testing Program is an applied research effort thatdetermines the technological needs of justice system agencies, sets minimum performance standards for specific devices,tests commercially available equipment against those standards, and disseminates the standards and the test results tocriminal justice agencies nationally and internationally.

The program operates through:The Law Enforcement and Corrections Technology Advisory Council (LECTAC) consisting of nationally

recognized criminal justice practitioners from Federal, State, and local agencies, which assesses technological needsand sets priorities for research programs and items to be evaluated and tested.

The Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology, whichdevelops voluntary national performance standards for compliance testing to ensure that individual items of equipmentare suitable for use by criminal justice agencies. The standards are based upon laboratory testing and evaluation ofrepresentative samples of each item of equipment to determine the key attributes, develop test methods, and establishminimum performance requirements for each essential attribute. In addition to the highly technical standards, OLESalso produces technical reports and user guidelines that explain in nontechnical terms the capabilities of availableequipment.

The National Law Enforcement and Corrections Technology Center (NLECTC), operated by a grantee, whichsupervises a national compliance testing program conducted by independent laboratories. The standards developed byOLES serve as performance benchmarks against which commercial equipment is measured. The facilities, personnel,and testing capabilities of the independent laboratories are evaluated by OLES prior to testing each item of equipment,and OLES helps the NLECTC staff review and analyze data. Test results are published in Equipment PerformanceReports designed to help justice system procurement officials make informed purchasing decisions.

Publications are available at no charge from the National Law Enforcement and Corrections Technology Center.Some documents are also available online through the Internet/World Wide Web. To request a document or additionalinformation, call 800-248-2742 or 301-519-5060, or write:

National Law Enforcement and Corrections Technology CenterP.O. Box 1160Rockville, MD 20849-1160E-mail: [email protected] Wide Web address: http://www.nlectc.org

National Institute of Justice

Jeremy TravisDirector

The Technical effort to develop this Guide was conductedunder Interagency Agreement 94-IJ-R-004

Project No. 97-027-CTT.

This Guide was prepared by the Office of Law Enforcement Standards (OLES) of the

National Institute of Standards and Technology (NIST)under the direction of A. George Lieberman,

Program Manager for Communications Systems,and Kathleen M. Higgins, Director of OLES.

The work resulting in this guide was sponsored bythe National Institute of Justice, David G. Boyd,

Director, Office of Science and Technology.

New Technology Batteries Guide

iii

FOREWORD

The Office of Law Enforcement Standards (OLES) of the National Institute of Standardsand Technology furnishes technical support to the National Institute of Justice program tostrengthen law enforcement and criminal justice in the United States. OLES’s function is toconduct research that will assist law enforcement and criminal justice agencies in the selectionand procurement of quality equipment.

OLES is: (1) subjecting existing equipment to laboratory testing and evaluation, and (2)conducting research leading to the development of several series of documents, includingnational standards, user guides, and technical reports.

This document covers research conducted by OLES under the sponsorship of the NationalInstitute of Justice. Additional reports as well as other documents are being issued under theOLES program in the areas of protective clothing and equipment, communications systems,emergency equipment, investigative aids, security systems, vehicles, weapons, and analyticaltechniques and standard reference materials used by the forensic community.

Technical comments and suggestions concerning this report are invited from all interestedparties. They may be addressed to the Director, Office of Law Enforcement Standards, NationalInstitute of Standards and Technology, Gaithersburg, MD 20899.

David G. Boyd, Director Office of Science and Technology National Institute of Justice


iv


v

A standard is not intended to informand guide the reader; that is the

function of a guideline

BACKGROUND

The Office of Law Enforcement Standards(OLES) was established by the NationalInstitute of Justice (NIJ) to provide focus on twomajor objectives: (1) to find existing equipmentwhich can be purchased today, and (2) todevelop new law-enforcement equipment whichcan be made available as soon as possible. Apart of OLES’s mission is to become thoroughlyfamiliar with existing equipment, to evaluate itsperformance by means of objective laboratorytests, to develop andimprove thesemethods of test, todevelop performancestandards forselected equipmentitems, and to prepareguidelines for theselection and use ofthis equipment. All of these activities aredirected toward providing law enforcementagencies with assistance in making goodequipment selections and acquisitions inaccordance with their own requirements.

As the OLES program has matured, there hasbeen a gradual shift in the objectives of theOLES projects. The initial emphasis on thedevelopment of standards has decreased, and theemphasis on the development of guidelines hasincreased. For the significance of this shift inemphasis to be appreciated, the precisedefinitions of the words “standard” and“guideline” as used in this context must beclearly understood.

A “standard” for a particular item of equipmentis understood to be a formal document, in a

conventional format, that details theperformance that the equipment is required togive, and describes test methods by which itsactual performance can be measured. Theserequirements are technical, and are stated interms directly related to the equipment’s use.The basic purposes of a standard are (1) to be areference in procurement documents created bypurchasing officers who wish to specifyequipment of the “standard” quality, and (2) to

identify objectivelyequipment ofacceptableperformance.

Note that a standardis not intended toinform and guide thereader; that is the

function of a “guideline.” Guidelines are writtenin non-technical language and are addressed tothe potential user of the equipment. Theyinclude a general discussion of the equipment,its important performance attributes, the variousmodels currently on the market, objective testdata where available, and any other informationthat might help the reader make a rationalselection among the various options oralternatives available to him or her.

This battery guide is provided to inform thereader of the latest technology related to batterycomposition, battery usage, and battery chargingtechniques.

Kathleen HigginsNational Institute of Standards and Technology

March 27, 1997


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vii

CONTENTS

page

FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

List of Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

1. Fundamentals of Battery Technology. . . . . . . . . . 11.1 What is a Battery?. . . . . . . . . . . . . . . . . . . . . 11.2 How Does a Battery Work?. . . . . . . . . . . . . . 11.3 Galvanic Cells vs. Batteries. . . . . . . . . . . . . . 31.4 Primary Battery. . . . . . . . . . . . . . . . . . . . . . . 31.5 Secondary Battery. . . . . . . . . . . . . . . . . . . . . 31.6 Battery Labels. . . . . . . . . . . . . . . . . . . . . . . . 3

2. Available Battery Types. . . . . . . . . . . . . . . . . . . . 52.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1.1 Acid vs. Alkaline. . . . . . . . . . . . . . . . . 52.1.2 Wet vs. Dry. . . . . . . . . . . . . . . . . . . . . 52.1.3 Categories. . . . . . . . . . . . . . . . . . . . . . 5

2.2 Vehicular Batteries. . . . . . . . . . . . . . . . . . . . 62.2.1 Lead-Acid . . . . . . . . . . . . . . . . . . . 62.2.2 Sealed vs. Flooded. . . . . . . . . . . . . . . 62.2.3 Deep-Cycle Batteries. . . . . . . . . . . . . . 72.2.4 Battery Categories for Vehicular

Batteries. . . . . . . . . . . . . . . . . . . . . . . . 72.3 “Household” Batteries. . . . . . . . . . . . . . . . . . 7

2.3.1 Zinc-carbon (Z-C). . . . . . . . . . . . . . . . 82.3.2 Zinc-Manganese Dioxide Alkaline Cells

(“Alkaline Batteries”) . . . . . . . . . . . . . 82.3.3 Rechargeable Alkaline Batteries. . . . . 92.3.4 Nickel-Cadmium (Ni-Cd). . . . . . . . . . 92.3.5 Nickel-Metal Hydride (Ni-MH) . . . . 102.3.6 Nickel-Iron (Ni-I) . . . . . . . . . . . . . . . 10

2.3.7 Nickel-Zinc (Ni-Z) . . . . . . . . . . . . . . 102.3.8 Lithium and Lithium Ion. . . . . . . . . . 10

2.4 Specialty Batteries (“Button” and MiniatureBatteries). . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.4.1 Metal-Air Cells. . . . . . . . . . . . . . . . . 122.4.2 Silver Oxide . . . . . . . . . . . . . . . . . . . 122.4.3 Mercury Oxide. . . . . . . . . . . . . . . . . 13

2.5 Other Batteries. . . . . . . . . . . . . . . . . . . . . . . 132.5.1 Nickel-Hydrogen (Ni-H). . . . . . . . . . 132.5.2 Thermal Batteries. . . . . . . . . . . . . . . 132.5.3 Super Capacitor. . . . . . . . . . . . . . . . . 132.5.4 The Potato Battery. . . . . . . . . . . . . . . 142.5.5 The Sea Battery. . . . . . . . . . . . . . . . . 142.5.6 Other Developments. . . . . . . . . . . . . 14

3. Performance, Economics and Tradeoffs. . . . . . . 153.1 Energy Densities. . . . . . . . . . . . . . . . . . . . . 153.2 Energy per Mass. . . . . . . . . . . . . . . . . . . . . 153.3 Energy Per Volume. . . . . . . . . . . . . . . . . . . 153.4 Memory Effects. . . . . . . . . . . . . . . . . . . . . . 163.5 Voltage Profiles. . . . . . . . . . . . . . . . . . . . . . 163.6 Self-Discharge Rates. . . . . . . . . . . . . . . . . . 173.7 Operating Temperatures. . . . . . . . . . . . . . . 173.8 Cycle Life . . . . . . . . . . . . . . . . . . . . . . . . . . 183.9 Capacity Testing. . . . . . . . . . . . . . . . . . . . . 183.10 Battery Technology Comparison. . . . . . . . 18

4. Selecting the Right Battery for the Application . 234.1 Battery Properties. . . . . . . . . . . . . . . . . . . . 244.2 Environmental Concerns. . . . . . . . . . . . . . . 244.3 Standardization. . . . . . . . . . . . . . . . . . . . . . 264.4 Testing Capacities. . . . . . . . . . . . . . . . . . . . 264.5 Mobile Radios. . . . . . . . . . . . . . . . . . . . . . . 274.6 Cellular Phones and PCS Phones. . . . . . . . 274.7 Laptop Computers. . . . . . . . . . . . . . . . . . . . 284.8 Camcorders. . . . . . . . . . . . . . . . . . . . . . . . . 284.9 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . 29

5. Battery Handling and Maintenance. . . . . . . . . . . 315.1 Battery Dangers. . . . . . . . . . . . . . . . . . . . . . 315.2 Extending Battery Life. . . . . . . . . . . . . . . . 33


viii

6. Battery Chargers and Adapters. . . . . . . . . . . . . . 356.1 Battery Chargers. . . . . . . . . . . . . . . . . . . . . 356.2 Charge Rates. . . . . . . . . . . . . . . . . . . . . . . . 366.3 Charging Techniques. . . . . . . . . . . . . . . . . . 366.4 Charging Lead-Acid Batteries. . . . . . . . . . . 366.5 Charging Ni-Cd Batteries. . . . . . . . . . . . . . 376.6 Timed-Charge Charging. . . . . . . . . . . . . . . 376.7 Pulsed Charge-Discharge Chargers. . . . . . . 386.8 Charging Button Batteries. . . . . . . . . . . . . . 386.9 Internal Chargers. . . . . . . . . . . . . . . . . . . . . 386.10 Battery Testers. . . . . . . . . . . . . . . . . . . . . . 386.11 “Smart” Batteries. . . . . . . . . . . . . . . . . . . . 396.12 End of Life . . . . . . . . . . . . . . . . . . . . . . . . 396.13 Battery Adapters. . . . . . . . . . . . . . . . . . . . 40

7. Products and Suppliers. . . . . . . . . . . . . . . . . . . . 417.1 Battery Manufacturers. . . . . . . . . . . . . . . . . 41

7.1.1 Battery Engineering. . . . . . . . . . . . . . 427.1.2 Duracell. . . . . . . . . . . . . . . . . . . . . . . 427.1.3 Eveready. . . . . . . . . . . . . . . . . . . . . . 427.1.4 Rayovac. . . . . . . . . . . . . . . . . . . . . . . 42

8. A Glossary of Battery Terms. . . . . . . . . . . . . . . 43

9. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

List of Figurespage

Figure 1. Conceptual diagram of a galvanic cell. . . . 1Figure 2. Energy densities, W#h/kg, of various battery

types (adapted from NAVSO P-3676).. . . . . . . 15Figure 3. Energy densities, W#h/L, of various battery

types (adapted from NAVSO P-3676).. . . . . . . 16Figure 4. Flat discharge curve vs. sloping discharge

curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Figure 5. Performance comparison of primary and

secondary alkaline and Ni-Cd batteries (adaptedfrom Design Note: Renewable Reusable AlkalineBatteries). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

List of Tablespage

Table 1. The Electromotive Series for Some BatteryComponents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Table 2. Various Popular Household-Battery Sizes . 8Table 3. Battery Technology Comparison (adapted from

Design Note: Renewable Reusable AlkalineBatteries) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Table 4. A Comparison of Several Popular BatteryTypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Table 5. Recommended Battery Types for VariousUsage Conditions. . . . . . . . . . . . . . . . . . . . . . . . 25

Table 6. Typical Usage of PortableTelecommunications Equipment.. . . . . . . . . . . . 27

Table 7. Charge Rate Descriptions. . . . . . . . . . . . . 35Table 8. Some On-Line Information Available via the

World Wide Web . . . . . . . . . . . . . . . . . . . . . . . . 41

List of Equationspage

Equation 1. The chemical reaction in a lead-acidbattery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Equation 2. The chemical reaction in a Leclanché cell.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Equation 3. The chemical reaction in a nickel-cadmium battery.. . . . . . . . . . . . . . . . . . . . . . . . . 9

Equation 4. The chemical reaction in a lithium-manganese dioxide cell.. . . . . . . . . . . . . . . . . . . 11


ix

COMMONLY USED SYMBOLS AND ABBREVIATIONS

A ampere H henry nm nanometerac alternating current h hour No. numberAM amplitude modulation hf high frequency o.d. outside diametercd candela Hz hertz (c/s) 6 ohmcm centimeter i.d. inside diameter p. pageCP chemically pure in inch Pa pascalc/s cycle per second ir infrared pe probable errord day J joule pp. pagesdB decibel L lambert ppm part per milliondc direct current L liter qt quart(C degree Celsius lb pound rad radian(F degree Fahrenheit lbf pound-force rf radio frequencydia diameter lbf#in pound-force inch rh relative humidityemf electromotive force lm lumen s secondeq equation ln logarithm (natural) SD standard deviationF farad log logarithm (common) sec. sectionfc footcandle M molar SWR standing wave ratiofig. figure m meter uhf ultrahigh frequencyFM frequency modulation min minute uv ultravioletft foot mm millimeter V voltft/s foot per second mph mile per hour vhf very high frequencyg acceleration/gravity m/s meter per second W wattg gram N newton � wavelengthgr grain N#m newton meter wt weight

area=unit2 (e.g., ft2, in2, etc.); volume=unit3 (e.g., ft2, m3, etc.)

PREFIXES

d deci (10-1) da deka (10)c centi (10-2) h hecto (102)m milli (10-3) k kilo (103)µ micro (10-6) M mega (106)n nano (10-9) G giga (109)p pico (10-12) T tera (1012)

COMMON CONVERSIONS (See ASTM E380)

ft/s×0.3048000=m/s lb×0.4535924=kgft×0.3048=m lbf×4.448222=Nft#lbf×1.355818=J lbf/ft×14.59390=N/mgr×0.06479891=g lbf#in×0.1129848=N##min×2.54=cm lbf/in2×6894.757=PakWh×3600000=J mph1.609344=km/h

qt×0.9463529=L

Temperature: (T(F�32)×5/9=T

(C

Temperature: (T(C×C9/5)+32=T

(F


x

1

Figure 1. Conceptual diagram of a galvanic cell.

1. Fundamentals of Battery Technology

1.1 WHAT IS A BATTERY ?

A battery, in concept, can be any device thatstores energy for later use. A rock, pushed tothe top of a hill, can be considered a kind ofbattery, since the energy used to push it up thehill (chemical energy, from muscles orcombustion engines) is converted and storedas potential kinetic energy at the top of thehill. Later, that energy is released as kineticand thermal energy when the rock rolls downthe hill.

Common use of theword, “battery,”however, is limitedto an electro-chemical devicethat convertschemical energyinto electricity, byuse of a galvaniccell. A galvanic cellis a fairly simpledevice consisting oftwo electrodes (ananode and acathode) and anelectrolyte solution. Batteries consist of one ormore galvanic cells.

1.2 HOW DOES A BATTERY WORK?

Figure 1 shows a simple galvanic cell.Electrodes (two plates, each made from adifferent kind of metal or metallic compound)are placed in an electrolyte solution. External

wires connect the electrodes to an electricalload (a light bulb in this case). The metal inthe anode (the negative terminal) oxidizes(i.e., it “rusts”), releasing negatively chargedelectrons and positively charged metal ions.The electrons travel through the wire (and theelectrical load) to the cathode (the positiveterminal). The electrons combine with thematerial in the cathode. This combinationprocess is called reduction, and it releases anegatively charged metal-oxide ion. At the

interface with theelectrolyte, this ioncauses a watermolecule to splitinto a hydrogen ionand a hydroxideion. The positivelycharged hydrogenion combines withthe negativelycharged metal-oxide ion andbecomes inert. Thenegatively chargedhydroxide ionflows through theelectrolyte to the

anode where it combines with the positivelycharged metal ion, forming a water moleculeand a metal-oxide molecule.

In effect, metal ions from the anode will“dissolve” into the electrolyte solution whilehydrogen molecules from the electrolyte aredeposited onto the cathode.


2

Anode Materials(Listed from worst

[most positive] to best[most negative])

Cathode Materials(Listed from best[most positive] to

worst [most negative])

Gold Ferrate

Platinum Iron Oxide

Mercury Cuprous Oxide

Palladium Iodate

Silver Cupric Oxide

Copper Mercuric Oxide

Hydrogen Cobaltic Oxide

Lead Manganese Dioxide

Tin Lead Dioxide

Nickel Silver Oxide

Iron Oxygen

Chromium Nickel Oxyhydroxide

Zinc Nickel Dioxide

Aluminum Silver Peroxide

Magnesium Permanganate

Lithium Bromate

Table 1. The Electromotive Series for SomeBattery Components

When the anode is fully oxidized or thecathode is fully reduced, the chemical reactionwill stop and the battery is considered to bedischarged.

Recharging a battery is usually a matter ofexternally applying a voltage across the platesto reverse the chemical process. Somechemical reactions, however, are difficult orimpossible to reverse. Cells with irreversiblereactions are commonly known as primarycells, while cells with reversible reactions areknown as secondary cells. It is dangerous toattempt to recharge primary cells.

The amount of voltage and current that agalvanic cell produces is directly related to thetypes of materials used in the electrodes andelectrolyte. The length of time the cell canproduce that voltage and current is related tothe amount of active material in the cell andthe cell’s design.

Every metal or metal compound has anelectromotive force, which is the propensity ofthe metal to gain or lose electrons in relationto another material. Compounds with apositive electromotive force will make goodanodes and those with a negative force willmake good cathodes. The larger the differencebetween the electromotive forces of the anodeand cathode, the greater the amount of energythat can be produced by the cell. Table 1shows the electromotive force of somecommon battery components. Over the years, battery specialists have

experimented with many differentcombinations of material and have generallytried to balance the potential energy output ofa battery with the costs of manufacturing thebattery. Other factors, such as battery weight,shelf life, and environmental impact, alsoenter into a battery’s design.


3

A battery is one or more galvaniccells connected in series or in

parallel

1.3 GALVANIC CELLS VS. BATTERIES

From earlier discussion, we know that abattery is one or more galvanic cells connectedin series or in parallel.

A battery composed of two 1.5 V galvaniccells connected in series, for example, willproduce 3 V. A typical 9 V battery is simplysix 1.5 V cells connected in series. Such aseries battery, however, will produce a currentthat is the equivalent to just one of thegalvanic cells.

A battery composed of two 1.5 V galvaniccells connected in parallel, on the other hand,will still produce avoltage of 1.5 V,but the currentprovided can bedouble the currentthat just one cellwould create. Sucha battery canprovide current twice as long as a single cell.

Many galvanic cells can be thus connected tocreate a battery with almost any current at anyvoltage level.

1.4 PRIMARY BATTERY

A primary battery is a battery that is designedto be cycled (fully discharged) only once andthen discarded. Although primary batteries areoften made from the same base materials assecondary (rechargeable) batteries, the designand manufacturing processes are not the same.

Battery manufacturers recommend thatprimary batteries not be recharged. Althoughattempts at recharging a primary battery willoccasionally succeed (usually with a

diminished capacity), it is more likely that thebattery will simply fail to hold any charge, willleak electrolyte onto the battery charger, orwill overheat and cause a fire. It is unwise anddangerous to recharge a primary battery.

1.5 SECONDARY BATTERY

A secondary battery is commonly known as arechargeable battery. It is usually designed tohave a lifetime of between 100 and 1000recharge cycles, depending on the compositematerials.

Secondary batteries are, generally, more costeffective over time than primary batteries,

since the batterycan be rechargedand reused. Asingle dischargecycle of a primarybattery, however,will provide morecurrent for a longer

period of time than a single discharge cycle ofan equivalent secondary battery.

1.6 BATTERY LABELS

The American National Standards Institute(ANSI) Standard, ANSI C18.1M-1992, listsseveral battery features that must be listed on abattery’s label. They are:

_ Manufacturer -- The name of the batterymanufacturer._ ANSI Number -- The ANSI/NEDAnumber of the battery._ Date -- The month and year that the batterywas manufactured or the month and year thatthe battery “expires” (i.e., is no longerguaranteed by the manufacturer)._ Voltage -- The nominal battery voltage.


4

_ Polarity -- The positive and negativeterminals. The terminals must be clearlymarked._ Warnings -- Other warnings and cautionsrelated to battery usage and disposal.

5

2. Available Battery Types

2.1 GENERAL

2.1.1 Acid vs. AlkalineBatteries are often classified by the type ofelectrolyte used in their construction. Thereare three common classifications: acid, mildlyacid, and alkaline.

Acid-based batteries often use sulphuric acidas the major component of the electrolyte.Automobile batteries are acid-based. Theelectrolyte used in mildly acidic batteries is farless corrosive than typical acid-based batteriesand usually includes a variety of salts thatproduce the desired acidity level. Inexpensivehousehold batteries are mildly acidic batteries.

Alkaline batteries typically use sodiumhydroxide or potassium hydroxide as the maincomponent of the electrolyte. Alkalinebatteries are often used in applications wherelong-lasting, high-energy output is needed,such as cellular phones, portable CD players,radios, pagers, and flash cameras.

2.1.2 Wet vs. Dry“Wet” cells refer to galvanic cells where theelectrolyte is liquid in form and is allowed toflow freely within the cell casing. Wetbatteries are often sensitive to the orientationof the battery. For example, if a wet cell isoriented such that a gas pocket accumulatesaround one of the electrodes, the cell will notproduce current. Most automobile batteries arewet cells.

“Dry” cells are cells that use a solid orpowdery electrolyte. These kind of electrolytesuse the ambient moisture in the air tocomplete the chemical process. Cells withliquid electrolyte can be classified as “dry” ifthe electrolyte is immobilized by somemechanism, such as by gelling it or by holdingit in place with an absorbent substance such aspaper.

In common usage, “dry cell” batteries willusually refer to zinc-carbon cells (Sec. 2.3.1)or zinc-alkaline-manganese dioxide cells(Sec. 2.3.2), where the electrolyte is oftengelled or held in place by absorbent paper.

Some cells are difficult to categorize. Forexample, one type of cell is designed to bestored for long periods without its electrolytepresent. Just before power is needed from thecell, liquid electrolyte is added.

2.1.3 CategoriesBatteries can further be classified by theirintended use. The following sections discussfour generic categories of batteries;“vehicular” batteries (Sec. 2.2), “household”batteries (Sec. 2.3), “specialty” batteries (Sec.2.4), and “other” batteries (Sec. 2.5). Eachsection will focus on the general properties ofthat category of battery.

Note that some battery types (acidic oralkaline, wet or dry) can fall into severaldifferent categories. For this guideline, batterytypes are placed into the category in which


6

Battery manufacturing is the singlelargest use for lead in the world.

PbO2�Pb�2H2SO4 �� 2PbSO4�2H2O

Equation 1. The chemical reaction in a lead-acid battery.

they are most likely to be found in commercialusage.

2.2 VEHICULAR BATTERIES

This section discusses battery types andconfigurations that are typically used in motorvehicles. This category can include batteriesthat drive electric motors directly or those thatprovide starting energy for combustionengines. This category will also include large,stationary batteries used as power sources foremergency building lighting, remote-sitepower, and computer back up.

Vehicular batteriesare usuallyavailable off-the-shelf in standarddesigns or can becustom built forspecificapplications.

2.2.1 Lead-AcidLead-acid batteries,developed in the late 1800s, were the firstcommercially practical batteries. Batteries ofthis type remain popular because they arerelatively inexpensive to produce and sell. Themost widely known uses of lead-acid batteriesare as automobile batteries. Rechargeablelead-acid batteries have become the mostwidely used type of battery in theworld—more than 20 times the use rate of itsnearest rivals. In fact, battery manufacturing isthe single largest use for lead in the world.1

Equation 1 shows the chemical reaction in alead-acid cell.

Lead-acid batteries remain popular becausethey can produce high or low currents over awide range of temperatures, they have goodshelf life and life cycles, and they arerelatively inexpensive to manufacture. Lead-

acid batteries areusuallyrechargeable.

Lead-acid batteriescome in all mannerof shapes and sizes,

from household batteries to large batteries foruse in submarines. The most noticeableshortcomings of lead-acid batteries are theirrelatively heavy weight and their fallingvoltage profile during discharge (Sec. 3.5).

2.2.2 Sealed vs. FloodedIn “flooded” batteries, the oxygen created atthe positive electrode is released from the celland vented into the atmosphere. Similarly, thehydrogen created at the negative electrode isalso vented into the atmosphere. The overallresult is a net loss of water (H2O) from thecell. This lost water needs to be periodicallyreplaced. Flooded batteries must be vented toprevent excess pressure from the build up ofthese gases. Also, the room or enclosurehousing the battery must be vented, since aconcentrated hydrogen and oxygenatmosphere is explosive.

1Encyclopedia of Physical Science andTechnology, Brooke Schumm, Jr., 1992.


7

In sealed batteries, however, the generatedoxygen combines chemically with the lead andthen the hydrogen at the negative electrode,and then again with reactive agents in theelectrolyte, to recreate water. The net result isno significant loss of water from the cell.

2.2.3 Deep-Cycle BatteriesDeep-cycle batteries are built in configurationssimilar to those of regular batteries, exceptthat they are specifically designed forprolonged use rather than for short bursts ofuse followed by a short recycling period. Theterm “deep-cycle” is most often applied tolead-acid batteries. Deep-cycle batteriesrequire longer charging times, with lowercurrent levels, than is appropriate for regularbatteries.

As an example, a typical automobile battery isusually used to provide a short, intense burstof electricity to the automobile’s starter. Thebattery is then quickly recharged by theautomobile’s electrical system as the engineruns. The typical automobile battery is not adeep-cycle battery.

A battery that provides power to a recreationalvehicle (RV), on the other hand, would beexpected to power lights, small appliances,and other electronics over an extended periodof time, even while the RV’s engine is notrunning. Deep-cycle batteries are moreappropriate for this type of continual usage.

2.2.4 Battery Categories for VehicularBatteries

Vehicular, lead-acid batteries are furthergrouped (by typical usage) into three differentcategories:

8 Starting-Lighting-Ignition (SLI) --Typically, these batteries are used for short,quick-burst, high-current applications. Anexample is an automotive battery, which isexpected to provide high current, occasionally,to the engine’s starter.8 Traction -- Traction batteries must providemoderate power through many deep dischargecycles. One typical use of traction batteries isto provide power for small electric vehicles,such as golf carts. This type of battery use isalso called Cycle Service.8 Stationary -- Stationary batteries musthave a long shelf life and deliver moderate tohigh currents when called upon. Thesebatteries are most often used for emergencies.Typical uses for stationary batteries are inuninteruptable power supplies (UPS) and foremergency lighting in stairwells and hallways.This type of battery use is also called Standbyor Float.

2.3 “H OUSEHOLD” BATTERIES

“Household” batteries are those batteries thatare primarily used to power small, portabledevices such as flashlights, radios, laptopcomputers, toys, and cellular phones. Thefollowing subsections describe thetechnologies for many of the formerly usedand presently used types of householdbatteries.

Typically, household batteries are small, 1.5 Vcells that can be readily purchased off theshelf. These batteries come in standard shapesand sizes as shown in Table 2. They can alsobe custom designed and molded to fit any sizebattery compartment (e.g., to fit inside acellular phone, camcorder, or laptopcomputer).


8

Size Shape and Dimensions Voltage

D Cylindrical, 61.5 mmtall, 34.2 mm diameter.

1.5 V

C Cylindrical, 50.0 mmtall, 26.2 mm diameter.

1.5 V

AA Cylindrical, 50.5 mmtall, 14.5 mm diameter.

1.5 V

AAA Cylindrical, 44.5 mmtall, 10.5 mm diameter

1.5 V

9 Volt Rectangular, 48.5 mmtall, 26.5 mm wide,

17.5 mm deep.

9 V

Note: Three other standard sizes of householdbatteries are available, AAAA, N, and 6-V (lantern)batteries. It is estimated that 90% of portable,battery-operated devices require AA, C, or Dbattery sizes.

Table 2. Various Popular Household-BatterySizes

Zn�2MnO2�2NH4Cl ��

Zn(NH3)2Cl2�2MnOOH

Equation 2. The chemical reaction in aLeclanché cell.

Most of the rest of this guideline will focus ondesigns, features, and uses of householdbatteries.

2.3.1 Zinc-carbon (Z-C)Zinc-carbon cells, also known as “Leclanchécells” are widely used because of theirrelatively low cost. Equation 2 shows thechemical reaction in a Leclanché cell. Theywere the first widely available householdbatteries. Zinc-carbon cells are composed of amanganese dioxide and carbon cathode, a zincanode, and zinc chloride (or ammoniumchloride) as the electrolyte.

Generally, zinc-carbon cells are notrechargeable and they have a slopingdischarge curve (i.e., the voltage leveldecreases relative to the amount of discharge).Zinc-carbon cells will produce 1.5 V, and theyare mostly used for non-critical uses such assmall household devices like flashlights andportable personal radios.

One notable drawback to these kind ofbatteries is that the outer, protective casing ofthe battery is made of zinc. The casing servesas the anode for the cell and, in some cases, ifthe anode does not oxidize evenly, the casingcan develop holes that allow leakage of themildly acidic electrolyte which can damagethe device being powered.

2.3.2 Zinc-Manganese Dioxide AlkalineCells (“Alkaline Batteries”)

When an alkaline electrolyte—instead of themildly acidic electrolyte—is used in a regularzinc-carbon battery, it is called an “alkaline”battery. An alkaline battery can have a usefullife of five to six times that of a zinc-carbonbattery. One manufacturer estimates that 30%of the household batteries sold in the world


9

Cd�2H2O�2NiOOH ��

2Ni(OH)2�Cd(OH)2

Equation 3. The chemical reaction in anickel-cadmium battery.

today are zinc-manganese dioxide (i.e.,alkaline) batteries.2,3

2.3.3 Rechargeable Alkaline BatteriesLike zinc-carbon batteries, alkaline batteriesare not generally rechargeable. One majorbattery manufacturer, however, has designed a“reusable alkaline” battery that they market asbeing rechargeable “25 times or more.”4

This manufacturer states that its batteries donot suffer from memory effects as the Ni-Cdbatteries do, and that their batteries have ashelf life that is much longer than Ni-Cdbatteries—almost as long as the shelf life ofprimary alkaline batteries.

Also, the manufacturer states that theirrechargeable alkaline batteries contain notoxic metals, such as mercury or cadmium, tocontribute to the poisoning of theenvironment.

Rechargeable alkaline batteries are mostappropriate for low- and moderate-powerportable equipment, such as hand-held toysand radio receivers.

2.3.4 Nickel-Cadmium (Ni-Cd)Nickel-cadmium cells are the most commonlyused rechargeable household batteries. Theyare useful for powering small appliances, suchas garden tools and cellular phones. The basicgalvanic cell in a Ni-Cd battery contains acadmium anode, a nickel hydroxide cathode,and an alkaline electrolyte. Equation 3 showsthe chemical reaction in a Ni-Cd cell. Batteriesmade from Ni-Cd cells offer high currents atrelatively constant voltage and they aretolerant of physical abuse. Nickel-cadmiumbatteries are also tolerant of inefficient usagecycling. If a Ni-Cd battery has incurredmemory loss (Sec. 3.4), a few cycles ofdischarge and recharge can often restore thebattery to nearly “full” memory.

Unfortunately, nickel-cadmium technology isrelatively expensive. Cadmium is anexpensive metal and is toxic. Recentregulations limiting the disposal of wastecadmium (from cell manufacturing or fromdisposal of used batteries) has contributed tothe higher costs of making and using thesebatteries.

These increased costs do have one unexpectedadvantage. It is more cost effective to recycleand reuse many of the components of a Ni-Cdbattery than it is to recycle components ofother types of batteries. Several of the majorbattery manufacturers are leaders in suchrecycling efforts.

2The Story of Packaged Power, DuracellInternational, Inc., July, 1995.

3Certain commercial companies, equipment,instruments, and materials are identified in this reportto specify adequately the technical aspects of thereported results. In no case does such identificationimply recommendation or endorsement by the NationalInstitute of Justice, or any other U.S. Governmentdepartment or agency, nor does it imply that thematerial or equipment identified is necessarily the bestavailable for the purpose.

4Household Batteries and the Environment,Rayovac Corporation, 1995.


10

Lithium will ignite or explode oncontact with water.

2.3.5 Nickel-Metal Hydride (Ni-MH)Battery designers have investigated severalother types of metals that could be usedinstead of cadmium to create high-energysecondary batteries that are compact andinexpensive. The nickel-metal-hydride cell is awidely used alternative.

The anode of a Ni-MH cell is made of ahydrogen storage metal alloy, the cathode ismade of nickel oxide, and the electrolyte is apotassium hydroxide solution.

According to one manufacturer, Ni-MH cellscan last 40% longer than the same size Ni-Cdcells and will have a life-span of up to 600cycles.5 This makes them useful for high-energy devices suchas laptopcomputers, cellularphones, andcamcorders.

Ni-MH batterieshave a high self-discharge rate and arerelatively expensive.

2.3.6 Nickel-Iron (Ni-I)Nickel-iron cells, also known as the Edisonbattery, are much less expensive to build andto dispose of than nickel-cadmium cells.Nickel-iron cells were developed even beforethe nickel-cadmium cells. The cells are ruggedand reliable, but do not recharge veryefficiently. They are widely used in industrialsettings and in eastern Europe, where iron andnickel are readily available and inexpensive.

2.3.7 Nickel-Zinc (Ni-Z)Another alternative to using cadmiumelectrodes is using zinc electrodes. Althoughthe nickel-zinc cell yields promising energyoutput, the cell has some unfortunateperformance limitations that prevent the cellfrom having a useful lifetime of more than 200or so charging cycles. When nickel-zinc cellsare recharged, the zinc does not redeposit inthe same “holes” on the anode that werecreated during discharge. Instead, the zincredeposits in a somewhat random fashion,causing the electrode to become misshapen.Over time, this leads to the physicalweakening and eventual failure of theelectrode.

2.3.8 Lithium andLithium Ion

Lithium is apromising reactantin batterytechnology, due toits high electro-

positivity. The specific energy of somelithium-based cells can be five times greaterthan an equivalent-sized lead-acid cell andthree times greater than alkaline batteries.6

Lithium cells will often have a starting voltageof 3.0 V. These characteristics translate intobatteries that are lighter in weight, have lowerper-use costs, and have higher and more stablevoltage profiles. Equation 4 shows thechemical reaction in one kind of lithium cell.

5The Story of Packaged Power, DuracellInternational, Inc., July, 1995.

6Why Use Energizer AA Lithium Batteries?,Eveready Battery Company, Inc., 1993.


11

Li�MnO2 �� LiMnO2

Equation 4. The chemical reaction in alithium-manganese dioxide cell.

Unfortunately, the same feature that makeslithium attractive for use in batteries—its highelectrochemical potential—also can causeserious difficulties in the manufacture and useof such batteries. Many of the inorganiccomponents of the battery and its casing aredestroyed by the lithium ions and, on contactwith water, lithium will react to createhydrogen which can ignite or can createexcess pressure in the cell. Many fireextinguishers are water based and will causedisastrous results if used on lithium products.Special D-class fire extinguishers must beused when lithium is known to be within theboundaries of a fire.7

Lithium also has a relatively low meltingtemperature for a metal, 180 (C (356 (F). Ifthe lithium melts, it may come into directcontact with the cathode, causing violentchemical reactions.

Because of the potentially violent nature oflithium, the Department of Transportation(DOT) has special guidelines for the transportand handling of lithium batteries. Contactthem to ask for DOT Regulations 49 CFR.

Some manufacturers are having success withlithium-iron sulfide, lithium-manganesedioxide, lithium-carbon monoflouride,lithium-cobalt oxide, and lithium-thionyl cells.

In recognition of the potential hazards oflithium components, manufacturers of lithium-based batteries have taken significant steps toadd safety features to the batteries to ensuretheir safe use.

Lithium primary batteries (in small sizes, forsafety reasons) are currently being marketedfor use in flash cameras and computermemory. Lithium batteries can last three timeslonger than alkaline batteries of the samesize.8 But, since the cost of lithium batteriescan be three times that of alkaline batteries,the cost benefits of using lithium batteries aremarginal.

Button-size lithium batteries are becomingpopular for use in computer memory back-up,in calculators, and in watches. In applicationssuch as these, where changing the battery isdifficult, the longer lifetime of the lithiumbattery makes it a desirable choice.

One company now produces secondarylithium-ion batteries with a voltage of 3.7 V,“four times the energy density of Ni-Cdbatteries,” “one-fifth the weight of Ni-Cdbatteries,” and can be recharged 500 times.9

In general, secondary (rechargeable) lithium-ion batteries have a good high-powerperformance, an excellent shelf life, and abetter life span than Ni-Cd batteries.Unfortunately, they have a very high initial

7Battery Engineering Web Site,http://www.batteryeng.com/, August 1997.

8Navy Primary and Secondary Batteries.Design and Manufacturing Guidelines, NAVSO P-3676, September 1991.

9Battery Engineering Web Site,http://www.batteryeng.com/, August 1997.


12

cost and the total energy available per usagecycle is somewhat less than Ni-Cd batteries.

2.4 SPECIALTY BATTERIES (“B UTTON” AND

MINIATURE BATTERIES )

“Button” batteries are the nickname given tothe category of batteries that are small andshaped like a coin or a button. They aretypically used for small devices such ascameras, calculators, and electronic watches.

Miniature batteries are very small batteriesthat can be custom built for devices, such ashearing aids and electronic “bugs,” whereeven button batteries can be too large. Industrystandardization has resulted in five to tenstandard types of miniature batteries that areused throughout the hearing-aid industry.

Together, button batteries and miniaturebatteries are referred to as specialty batteries.

Most button and miniature batteries need avery high energy density to compensate fortheir small size. The high energy density isachieved by the use of highly electro-positive—and expensive—metals such assilver or mercury. These metals are not costeffective enough to be used in larger batteries.

Several compositions of specialty batteries aredescribed in the following sections.

2.4.1 Metal-Air CellsA very practical way to obtain high energydensity in a galvanic cell is to utilize theoxygen in air as a “liquid” cathode. A metal,such as zinc or aluminum, is used as theanode. The oxygen cathode is reduced in aportion of the cell that is physically isolatedfrom the anode. By using a gaseous cathode,

more room is available for the anode andelectrolyte, so the cell size can be very smallwhile providing good energy output. Smallmetal-air cells are available for applicationssuch as hearing aids, watches, and clandestinelistening devices.

Metal-air cells have some technicaldrawbacks, however. It is difficult to build andmaintain a cell where the oxygen acting as thecathode is completely isolated from the anode.Also, since the electrolyte is in direct contactwith air, approximately one to three monthsafter it is activated, the electrolyte will becometoo dry to allow the chemical reaction tocontinue. To prevent premature drying of thecells, a seal is installed on each cell at the timeof manufacture. This seal must be removed bythe customer prior to first use of the cell.Alternately, the manufacturer can provide thebattery in an air-tight package.

2.4.2 Silver OxideSilver oxide cells use silver oxide as thecathode, zinc as the anode, and potassiumhydroxide as the electrolyte. Silver oxide cellshave a moderately high energy density and arelatively flat voltage profile. As a result, theycan be readily used to create specialtybatteries. Silver oxide cells can providehigher currents for longer periods than mostother specialty batteries, such as thosedesigned from metal-air technology. Due tothe high cost of silver, silver oxide technologyis currently limited to use in specialtybatteries.

2.4.3 Mercury OxideMercury oxide cells are constructed with azinc anode, a mercury oxide cathode, andpotassium hydroxide or sodium hydroxide asthe electrolyte. Mercury oxide cells have a


13

high energy density and flat voltage profileresembling the energy density and voltageprofile of silver oxide cells. These mercuryoxide cells are also ideal for producingspecialty batteries. The component, mercury,unfortunately, is relatively expensive and itsdisposal creates environmental problems.

2.5 OTHER BATTERIES

This section describes battery technology thatis not mature enough to be available off-the-shelf, has special usage limitations, or isotherwise impractical for general use.

2.5.1 Nickel-Hydrogen (Ni-H)Nickel-hydrogen cells were developed for theU.S. space program. Under certain pressuresand temperatures, hydrogen (which is,surprisingly, classified as an alkali metal) canbe used as an active electrode opposite nickel.Although these cells use an environmentallyattractive technology, the relatively narrowrange of conditions under which they can beused, combined with the unfortunate volatilityof hydrogen, limits the long-range prospects ofthese cells for terrestrial uses.

2.5.2 Thermal BatteriesA thermal battery is a high-temperature,molten-salt primary battery. At ambienttemperatures, the electrolyte is a solid, non-conducting inorganic salt. When power isrequired from the battery, an internalpyrotechnic heat source is ignited to melt thesolid electrolyte, thus allowing electricity to begenerated electrochemically for periods from afew seconds to an hour. Thermal batteries arecompletely inert until the electrolyte is meltedand, therefore, have an excellent shelf life,require no maintenance, and can tolerate

physical abuse (such as vibrations or shocks)between uses.

Thermal batteries can generate voltages of 1.5 V to 3.3 V, depending on the battery’scomposition. Due to their rugged constructionand absence of maintenance requirements,they are most often used for militaryapplications such as missiles, torpedoes, andspace missions and for emergency-powersituations such as those in aircraft orsubmarines.

The high operating temperatures and shortactive lives of thermal batteries limit their useto military and other large-institutionapplications.

2.5.3 Super CapacitorThis kind of battery uses no chemical reactionat all. Instead, a special kind of carbon (carbonaerogel), with a large molecular surface area,is used to create a capacitor that can hold alarge amount of electrostatic energy.10 Thisenergy can be released very quickly, providinga specific energy of up to 4000 Watt-hours perkilogram (Wh/kg), or it can be regulated toprovide smaller currents typical of manycommercial devices such as flashlights, radios,and toys. Because there are no chemicalreactions, the battery can be rechargedhundreds of thousands of times withoutdegradation. Other potential advantages of thiskind of cell are its low cost and widetemperature range. One disadvantage,however, is its high self-discharge rate. Thevoltage of some prototypes is approximately2.5 V.

10PolyStor Web Page, http://www.polystor.com/, August, 1997.


14

2.5.4 The Potato BatteryOne interesting science experiment involvessticking finger-length pieces of copper andzinc wire, one at a time, into a raw potato tocreate a battery. The wires will carry a veryweak current which can be used to power asmall electrical device such as a digital clock.

One vendor sells a novelty digital watch that ispowered by a potato battery. The wearer mustput a fresh slice of potato in the watch everyfew days.

2.5.5 The Sea BatteryAnother interesting battery design uses a rigidframework, containing the anode and cathode,which is immersed into the ocean to use seawater as the electrolyte. This configurationseems promising as an emergency battery formarine use.

2.5.6 Other DevelopmentsScientists are continually working on newcombinations of materials for use in batteries,as well as new manufacturing methods toextract more energy from existingconfigurations.

15

Figure 2. Energy densities, W#h/kg, of variousbattery types (adapted from NAVSO P-3676).

3. Performance, Economics and Tradeoffs

3.1 ENERGY DENSITIES

The energy density of a battery is a measure ofhow much energy the battery can supplyrelative to its weight or volume. A battery withan energy density twice that of another batteryshould, theoretically, have an active lifetimetwice as long.

The energy density of a battery is mainlydependent on the composition of its activecomponents. A chemist can use mathematicalequations to determine the theoreticalmaximum voltage and current of a proposedcell, if the chemical composition of the anode,cathode, and electrolyte of the cell are allknown. Various physical attributes, such aspurity of the reactants and the particulars ofthe manufacturing process can cause themeasured voltage, current, and capacity to belower than their theoretical values.

3.2 ENERGY PER MASS

Figure 2 compares the gravimetric energydensities of various dry cell systemsdischarged at a constant rate for temperatures between -40 (C (-40 (F) and 60 (C (140 (F).

Of the systems shown, the zinc-air cellproduces the highest gravimetric energydensity. Basic zinc-carbon cells have thelowest gravimetric energy density.

3.3 ENERGY PER VOLUME

Figure 3 compares the volumetric energydensities of various dry cell systemsdischarged at a constant rate for temperaturesbetween -40 (C (-40 (F) and 60 (C (140 (F).

Of the systems shown, the zinc-air cellproduces the highest volumetric energydensity. Basic zinc-carbon cells have thelowest volumetric energy density. The curvesfor secondary battery cells are not shown inthe tables.


16

Figure 3. Energy densities, W#h/L, of variousbattery types (adapted from NAVSO P-3676).

Of the major types of secondary cells, Ni-Cdbatteries and wet-cell lead-acid batteries haveapproximately the same volumetric energydensity. Ni-MH batteries have approximatelytwice the volumetric energy density of Ni-Cdbatteries.

3.4 MEMORY EFFECTS

As a rechargeable battery is used, recharged,and used again, it loses a small amount of itsoverall capacity. This loss is to be expected inall secondary batteries as the active compo-nents become irreversibly consumed.

Ni-Cd batteries, however, suffer an additionalproblem, called the memory effect. If a Ni-Cdbattery is only partially discharged beforerecharging it, and this happens several times ina row, the amount of energy available for thenext cycle will only be slightly greater than theamount of energy discharged in the cell’smost-recent cycle. This characteristic makes itappear as if the battery is “remembering” how

much energy is needed for a repeatedapplication.

The physical process that causes the memoryeffect is the formation of potassium-hydroxidecrystals inside the cells. This build up ofcrystals interferes with the chemical process ofgenerating electrons during the next battery-use cycle. These crystals can form as a resultof repeated partial discharge or as a result ofovercharging the Ni-Cd battery.

The build up of potassium-hydroxide crystalscan be reduced by periodically reconditioningthe battery. Reconditioning of a Ni-Cd batteryis accomplished by carefully controlled powercycling (i.e., deeply discharging and thenrecharging the battery several times). Thispower cycling will cause most of the crystalsto redissolve back into the electrolyte. Severalcompanies offer this reconditioning service,although battery users can purchase areconditioner and recondition their ownbatteries. Some batteries can be reconditionedwithout a special reconditioner by completelydraining the battery (using the battery powereddevice itself or a resistive circuit designed tosafely discharge the battery) and charging it asnormal.

3.5 VOLTAGE PROFILES

The voltage profile of a battery is the relation-ship of its voltage to the length of time it hasbeen discharging (or charging). In mostprimary batteries, the voltage will dropsteadily as the chemical reactions in the cellare diminished. This diminution leads to analmost-linear drop in voltage, called a slopingprofile. Batteries with sloping voltage profilesprovide power that is adequate for many


17

Figure 4. Flat discharge curve vs. slopingdischarge curve.

applications such as flashlights, flash cameras,and portable radios.

Ni-Cd batteries provide a relatively flatvoltage profile. The cell’s voltage will remainrelatively constant for more than E of itsdischarge cycle. At some point near the end ofthe cycle, the voltage drops sharply to nearlyzero volts. Batteries with this kind of profileare used for devices that require a relativelysteady operating voltage.

One disadvantage of using batteries with a flatvoltage profile is that the batteries will need tobe replaced almost immediately after a drop involtage is noticed. If they are not immediatelyreplaced, the batteries will quickly cease toprovide any useful energy.

Figure 4 shows the conceptual differencebetween a flat discharge rate and a slopingdischarge rate.

Figure 5 (Sec. 5) shows actual voltageprofiles for several common battery types.

3.6 SELF-DISCHARGE RATES

All charged batteries (except thermal batteriesand other batteries specifically designed for anear-infinite shelf life) will slowly lose theircharge over time, even if they are notconnected to a device. Moisture in the air andthe slight conductivity of the battery housingwill serve as a path for electrons to travel tothe cathode, discharging the battery. The rateat which a battery loses power in this way iscalled the self-discharge rate.

Ni-Cd batteries have a self-discharge rate ofapproximately 1% per day. Ni-MH batterieshave a much higher self-discharge rate ofapproximately 2% to 3% per day. These highdischarge rates require that any such battery,which has been stored for more than a month,be charged before use.

Primary and secondary alkaline batteries havea self-discharge rate of approximately 5% to10% per year, meaning that such batteries canhave a useful shelf life of several years.Lithium batteries have a self-discharge rate ofapproximately 5% per month.

3.7 OPERATING TEMPERATURES

As a general rule, battery performancedeteriorates gradually with a rise intemperature above 25 (C (77 (F), andperformance deteriorates rapidly attemperatures above 55 (C (131 (F). At verylow temperatures -20 (C (-4 (F) to 0 (C (32 (F), battery performance is only a fractionof that at 25 (C (77 (F). Figure 2 and Figure3 show the differences in energy density as afunction of temperature.

At low temperatures, the loss of energycapacity is due to the reduced rate of chemical


18

reactions and the increased internal resistanceof the electrolyte. At high temperatures, theloss of energy capacity is due to the increaseof unwanted, parasitic chemical reactions inthe electrolyte.

Ni-Cd batteries have a recommendedtemperature range of +17 (C (62 (F) to 37 (C(98 (F). Ni-MH have a recommendedtemperature range of 0 (C (32 (F) to 32 (C(89 (F).

3.8 CYCLE L IFE

The cycle life of a battery is the number ofdischarge/recharge cycles the battery cansustain, with normal care and usage patterns,before it can no longer hold a useful amountof charge.

Ni-Cd batteries should have a normal cyclelife of 600 to 900 recharge cycles. Ni-MHbatteries will have a cycle life of only 300 to400 recharge cycles. As with all rechargeablebatteries, overcharging a Ni-Cd or Ni-MHbattery will significantly reduce the number ofcycles it can sustain.

3.9 CAPACITY TESTING

Many battery manufacturers recommend theconstant-load test to determine the capacity ofa battery. This test is conducted by connectinga predetermined load to the battery and thenrecording the amount of time needed todischarge the battery to a predetermined level.

Another recommended test is the intermittent-or switching-load test. In this type of test, apredetermined load is applied to the battery fora specified period and then removed foranother period. This load application andremoval is repeated until the battery reaches a

predetermined level of discharge. This kind of test simulates the battery usage of a portableradio.

A comparison of these two kinds of tests wasperformed on five commonly available typesof batteries.11 The data shows that the fivetested batteries all had a constant-loadduration of 60 to 80 minutes, which indicatesthat the five batteries had similar capacities.

But, intermittent-load testing of those samefive batteries showed that the duration of thebatteries ranged from 8.5 hours to 12 hours. There was no correlation of the results of thetwo tests, meaning that batteries thatperformed best under constant-load testing didnot necessarily perform well underintermittent-load testing. The study concludedthat the ability of a battery to recover itselfbetween heavy current drains cannot be madeapparent through a constant-load test.

3.10 BATTERY TECHNOLOGY COMPARISON

Table 3 shows a comparison of some of theperformance factors of several commonbattery types.

The initial capacity of a battery refers to theelectrical output, expressed in ampere-hours,which the fresh, fully charged battery candeliver to a specified load. The rated capacityis a designation of the total electrical output ofthe battery at typical discharge rates; e.g., foreach minute of radio transceiver operation, 6seconds shall be under a transmit current

11Batteries Used with Law EnforcementCommunications Equipment: Chargers and ChargingTechniques, W. W. Scott, Jr., U.S. Department ofJustice, LESP-RPT-0202.00, June 1973.


19

(See Sec. 3.10) Ni-Cd Ni-MH PrimaryAlkaline

SecondaryAlkaline

Initial Capacity r || NNNN qqq

Rated Capacity NNNN qqq || r

Self-Discharge || r NNNN NNNN

Cycle Life NNNN NNNN r qqq

Initial Cost* || r NNNN qqq

Life-Cycle Cost* qqq qqq r qqq

Worst Performance = r, Low Performance = ||,Good Performance= qqq, Best Performance =NNNN*A better performance ranking means lower costs.

Table 3. Battery Technology Comparison (adapted fromDesign Note: Renewable Reusable Alkaline Batteries)

drain, 6 seconds shall be under a receivecurrent drain and 48 seconds shall be under astandby current drain.

The self-discharge rate is the rate at which thebattery will lose its charge during storage orother periods of non-use. The cycle life is thenumber of times that the rechargeable batterycan be charged and discharged before itbecomes no longer able to hold or deliver anyuseful amount of energy.

The initial cost is the relative cost ofpurchasing the battery. The life-cycle cost isthe per-use relative cost of the battery.

Table 4 shows a more detailed comparison ofmany of the available battery types.

New

Tech

no

logy B

atteries Gu

ide

20

Cell Type* BasicType**

Anodematerial

CathodeMaterial

MainElectrolyteMaterial

VoltsperCell

Advantages &Applications

Disadvantages

Carbon-Zinc(“Leclanché”)

P Zinc Manganesedioxide

Ammoniumchloride, zinc

chloride

1.5 Low cost, good shelflife. Useful forflashlights, toys, andsmall appliances.

Output capacitydecreases as itdrains; poorperformance atlow temperatures.

Zinc Chloride P Zinc Manganesedioxide

Zinc Chloride 1.5 Good service at highdrain, leak resistant,good low-temperatureperformance. Useful forflashlights, toys, andsmall appliances.

Relativelyexpensive fornovelty usage.

“Alkaline”(Zinc-

ManganeseDioxide)

P or S Zinc Manganesedioxide

Potassiumhydroxide

1.5 High efficiency undermoderate, continuousdrains, long shelf life,good low-temperatureperformance. Useful forcamera flash units,motor-driven devices,portable radios.

Primary cells areexpensive fornovelty usage.Secondary cellshave a limitednumber ofrecharge cycles.

Car Battery(Lead-Acid)

S Lead Lead dioxide Sulfuric acid 2 Low cost, spill resistant(sealed batteries). Usefulfor automobiles andcordless electric lawnmowers.

Limited low-temperatureperformance.Vented cellsrequiremaintenance.Cells are relativelyheavy.

* -- Common name, ** -- P=Primary, S=Secondary (Rechargeable)

Table 4. A Comparison of Several Popular Battery Types

New

Tech

no

logy B

atteries Gu

ide

21


Anodematerial

CathodeMaterial


VoltsperCell


Disadvantages

“Ni-Cd” (Nickel-Cadmium)

S Cadmium Nickelhydroxide

Potassiumhydroxide

1.25 Excellent cycle life; flatdischarge curve; goodhigh- and low-temperatureperformance; highresistance to shock andvibration. Useful forsmall appliances thathave intermittent usage,such as walkie-talkies,portable hand tools, tapeplayers, and toys. Whenbatteries are exhausted,they can be rechargedbefore the next neededuse.

High initial cost;only fair chargeretention;memory effect.

Mercuric Oxide P Zinc Mercuricoxide

Potassiumhydroxide

1.35 Relatively flat dischargecurve; relatively highenergy density; goodhigh-temperatureperformance; goodservice maintenance.Useful for criticalappliances, such aspaging, hearing aids, andtest equipment.

Poor low-temperatureperformance insome situations.


Table 4 (continued)

New

Tech

no

logy B

atteries Gu

ide

22


Anodematerial

CathodeMaterial


VoltsperCell


Disadvantages

“Ni-MH”(Nickel-Metal

Hydride)

S Hydrogenstorage metal

Nickel oxide Potassiumhydroxide

1.5 No memory effects (suchas Ni-Cd has), goodhigh-powerperformance, good low-temperatureperformance. Useful forportable devices wherethe duty cycle variesfrom use to use.

High initial cost,relatively highrate of self-discharge.

Silver Oxide P or S Zinc Silver oxide Potassiumhydroxide

1.5 High energy density; flatdischarge curve. Usefulfor very small appliancessuch as calculators,watches, and hearingaids.

Silver is veryexpensive; poorstorage andmaintenancecharacteristics.Rechargeablecells have a verylimited number ofcycles.

Zinc-Air P Zinc Oxygen Potassiumhydroxide

1.25 High energy density insmall cells. Flatdischarge rate.

Dries out quickly.

Lithium P Lithium Iron sulfide Lithium saltsin ether

1.0 -3.6

Good energy density. Limited high-ratecapacities; safetyconcerns.


Table 4 (continued)

23

Figure 5. Performance comparison of primary andsecondary alkaline and Ni-Cd batteries (adapted fromDesign Note: Renewable Reusable Alkaline Batteries).

4. Selecting the Right Battery for theApplication

Batteries come in many different shapes, sizes,and compositions. There is no one “ideal”battery that can satisfy all possiblerequirements equally. Different batterytechnologies have been developed that willoptimize certain parameters for specificbattery uses.

In general, theenergy outputof a battery isrelated only toits size andmaterialcomposition.Differentbattery designsand differentmanufacturingmethods (forthe same type,size, andcomposition ofbattery) will, ingeneral, lead toonly minordifferences inthe batteries’ electrical output. Battery-industry standards have contributed to the factthat batteries (of the same type, composition,and size) from different manufacturers arequite interchangeable.

However, the small differences that do existbetween batteries made by differentmanufacturers, can be significant when using amulti-cell array of matched cells. In thesecases, potential replacement cells must begraded to see if the cells properly match thecapacity of the existing cells.

Even for non-matched, multi-cellapplications,such asflashlights,portable radios,etc., it is still agood rule ofthumb to avoidmixing batteriesfrom differentmanufacturerswithin onedevice. Smallvariances involtage andcurrent,between

different brands of battery, can slightly shortenthe useful life span of all of the batteries.

Do not mix batteries of different types (e.g.,do not mix rechargeable alkaline batteries withNi-Cd batteries) within a single device orwithin an array of batteries.


24

Figure 5 shows some discharge curves forseveral popular AA size battery types. Two ofthe curves (secondary alkaline [1st use] and[25th use]) show that secondary alkalinebatteries rapidly lose their capacity as they areused and recharged. Only one Ni-Cd curve isshown, since its curve remains essentially thesame throughout most its life span.

4.1 BATTERY PROPERTIES

Battery applications vary, as do considerationsfor selecting the correct battery for eachapplication. Some of the important factors thatcustomers might consider when selecting theright battery for a particular application arelisted below:

Chemistry -- Which kind ofbattery chemistry is best for the application?Different chemistries will generate differentvoltages and currents.

Primary or Secondary -- Primarybatteries are most appropriate for applicationswhere infrequent, high-energy output isrequired. Secondary batteries are mostappropriate for use in devices that see steadyperiods of use and non-use (pagers, cellularphones, etc.).

Standardization andAvailability -- Is there an existing batterydesign that meets the application needs? Willreplacement batteries be available in thefuture? Using existing battery types is almostalways preferable to specifying a custom-madebattery design.

Flexibility -- Can the batteryprovide high or low currents over a wide rangeof conditions?

Temperature Range -- Can thebattery provide adequate power over the

expected temperature range for theapplication?

Good Cycle Life -- How manytimes can the rechargeable battery bedischarged and recharged before it becomesunusable?

Costs -- How expensive is thebattery to purchase? Does the battery requirespecial handling?

Shelf Life -- How long can thebattery be stored without loss of a significantamount of its power?

Voltage -- What is the voltage ofthe battery? [Most galvanic cells producevoltages of between 1.0 and 2.0 V.]

Safety -- Battery componentsrange from inert, to mildly corrosive, to highlytoxic or flammable. The more hazardouscomponents will require additional safetyprocedures.

Hidden Costs -- Simplermanufacturing processes result in lower costbatteries. However, if a battery contains toxicor hazardous components, extra costs will beincurred to dispose of the battery safely afterits use.

Table 5 shows a short list of different batterytypes and the kinds of application that areappropriate for each.

4.2 ENVIRONMENTAL CONCERNS

All battery components, when discarded,contribute to the pollution of the environment.Some of the components, such as paperboardand carbon powder, are relatively organic andcan quickly merge into the ecosystem withoutnoticeable impact. Other components, such assteel, nickel, and plastics, while not actively


25

BatteryType

DeviceDrain Rate

Device UseFrequency

PrimaryAlkaline

High Moderate

SecondaryAlkaline

Moderate Moderate

PrimaryLithium

High Frequent

SecondaryNi-Cd

High Frequent

Primary Zn-C(“HeavyDuty”)

Moderate Regular

Primary Zn-C(“Standard”)

Low Occasional

Table 5. Recommended Battery Types forVarious Usage Conditions

Many of the major battery manufacturershave put significant efforts into therecycling of discarded batteries.

toxic to the ecosystem, will add to the volumeof a landfill, since they decompose slowly.

Of most concern,however, are theheavy-metal batterycomponents,which, whendiscarded, can betoxic to plants,animals, andhumans. Cadmium, lead, and mercury are theheavy-metal components most likely to be thetarget of environmental concerns.

Several of the major battery manufacturershave taken steps to reduce the amount of toxicmaterials in their batteries. One manufacturerreports the reduction of the mercury content oftheir most-popular battery from 0.75%, in

1980, to 0.00%, in 1996.12 Othermanufacturers report that their current batteryformulas contain no mercury. The U.S.Department of Mines, in 1994, estimated that,for the U.S. production of household batteries,mercury usage had fallen from 778 tons in1984 to (a projected) 10 tons in 1995.13

Many of the major battery manufacturers haveput significant efforts into the recycling ofdiscarded batteries. According to onemanufacturer, it takes six to ten times moreenergy to recycle a battery than to create thebattery components from virgin materials.Efforts are underway that could improve therecycling technology to make recyclingbatteries much more energy efficient and costeffective.14

The use of secondary (rechargeable) batteriesis more cost efficient than the use of primarybatteries. Such use will reduce the physicalvolume of discarded batteries in landfills,because the batteries can be recharged andreused 25 to 1000 times before they must be

discarded.

12Eveready and the Environment, EvereadyBattery Company, Inc., 1995.




26

The most popular secondary batteries,however, contain cadmium. Manymanufacturers, responding to customerrequests and legislative demands, aredesigning nickel-metal hydride, lithium-ion,and rechargeable-alkaline secondary batteriesthat contain only trace amounts of cadmium,lead, or mercury.

4.3 STANDARDIZATION

Existing off-the-shelf batteries are oftenpreferred to batteries that require specialdesign and manufacturing. Some benefits ofusing off-the-shelf batteries are listed below:

The use of a proven design canreduce the risk of the battery not workingproperly.

The use of tested technologyeliminates costly and time-consumingdevelopment efforts.

The use of a proven design reducesunit production costs because of competitive,multi-source availability.

The use of tested technologyreduces operations and support costs throughcommonality of training, documentation, andreplacement efforts.

4.4 TESTING CAPACITIES

One method of estimating battery capacityrequirements for a specific battery-powereddevice is to calculate the current drawn duringthe typical duty cycle for the device.

Standard duty cycles for battery service lifeand capacity determinations are defined inEIA/TIA Standard 60315 for land mobile radiocommunications and NIJ Standard-0211.0116

for hand-held portable radio applications.Specifically, in an average 1 minute period ofmobile-radio usage, 6 seconds (10%) is spentreceiving, 6 seconds (10%) is spenttransmitting and 48 seconds (80%) is spent inthe idle mode. Table 8 provides an exampleof a transceiver drawing an average current of8.0 + 6.2 + 32.5 = 46.7 mA. For a typical dutycycle composed of 8 hours of operation(followed by 16 hours of rest) a minimumbattery capacity of 374 mAh is required. Onemanufacturer of portable communicationsequipment recommends that batteries bereplaced if they fail to deliver 80% or more oftheir original rated capacity. Below 80%batteries are usually found to deterioriatequickly. Because a minimum requirement of374 mAh is 75% of the rated capacity of a 500mAh battery, the latter should adequatelyprovide power for the entire duty described.17

15Land Mobile FM or PM CommunicationsEquipment, Measurement and Performance Standard,Electronics Industry Association/TelecommunicationsIndustry Association, Publication EIA/TIA 603, 1993.

16Rechargeable Batteries for Personal/Portable Transceivers, National Institute of Justice,NIJ Standard-0211.01, 1995.

17Batteries Used with Law EnforcementCommunications Equipment: Chargers and ChargingTechniques, W.W. Scott, Jr., National Institute ofJustice, LESP-RPT-0202.00, June 1973.


27

StandbyMode

ReceiveMode

TransmitMode

Percent ofDuty Cycle

80%(48 minutes

of eachhour)

10%(6 minutes

of eachhour)

10%(6 minutes ofeach hour)

CurrentDrain for Mode

10 mA 62 mA 325 mA

AverageCurrent forMode

8.0 mA 6.2 mA 32.5 mA

Table 6. Typical Usage of PortableTelecommunications Equipment.

Similar calculations can be performed for anybattery in any battery-powered device by usingthe data relevant to the device and theproposed battery. The manufacturers shouldeither provide such appropriate informationwith the batteries and devices, or they shouldbe able to provide those data on request.

4.5 MOBILE RADIOS

As reported above, mobile radios have atypical duty cycle of 10% transmit, 10%receive, and 80% standby. The maximumcurrent drain will occur during the transmitcycle. Each radio, typically, will have a dailycycle of 8 hours of use and 16 hours of non-use. The non-use hours may be used to chargethe radio’s batteries.

Most commercial, off-the-shelf mobile-radiounits include a battery. But, since many radiounits are in service 7 days a week, 52 weeks ayear, and since the batteries are discharged andrecharged daily, each set of batteries shouldwear out approximately once every two years(~700 recharge cycles). Replacement batteries

should be purchased as directed by the usermanual for the unit.

4.6 CELLULAR PHONES AND PCS PHONES

Most commercial, off-the-shelf cellularphones contain a battery when purchased. Charging units may be supplied with thephone or may be purchased separately.

Typical usage for cellular telephones will varysignificantly with user, but, the estimate formobile radio usage (10% of the duty cycle isspent in transmit mode, 10% in receive mode,and 80% in standby mode) is also a reasonableestimate for cellular phone usage. At the endof each usage cycle, the user places the battery(phone) on a recharging unit that will chargethe battery for the next usage cycle. This usagepattern is appropriate for Ni-Cd or Ni-MHbatteries. Ni-Cd batteries should becompletely discharged between uses toprevent memory effects created by a recurringduty cycle.

When a replacement or spare battery isneeded, only replacements, recommended bythe phone manufacturer should be used.

Batteries and battery systems from othermanufacturers may be used if the batteries arecertified to work with that particular brand andmodel of phone. Damage to the phone mayresult if non-certified batteries are used.

Several battery manufacturers makereplacement battery packs that are designed towork with a wide variety of cellular phones. Because of the variety of phones available,battery manufacturers must design and sellseveral dozen different types of batteries to fitthe hundreds of models of cellular phones


28

from dozens of different manufacturers.18 Theuser is advised to check battery inter-operability charts before purchasing areplacement battery.

One battery manufacturer offers a batteryreplacement system that allows a phone ownerto use household primary batteries, insertedinto a special housing (called a refillablebattery pack), to replace the phone’s regularrechargeable battery pack. This refillable pack,says the manufacturer, is designed for light-use customers, who require that their phone’sbatteries have the long shelf life of primarybatteries. This refillable pack can also be usedin emergencies, for example, where thephone’s rechargeable battery pack isexhausted and no recharged packs areavailable. Primary household batteries can bereadily purchased (or borrowed from otherdevices), inserted into the refillable pack, andused to power the phone.19

4.7 LAPTOP COMPUTERS

Most commercial, off-the-shelf laptopcomputers have a built-in battery system. Inaddition to the battery provided, most laptopswill have a battery adapter that also serves as abattery charger.

The expected usage of a laptop computer isthat the operator will use it several times aweek, for periods of several hours at a time. The computer will drain the battery at amoderate rate when the computer is running,

and at the self-discharge rate when thecomputer is shut off. Quite often, the user willuse the computer until the “low battery” alarmsounds. At this point, the battery will bedrained of 90% of its charge before the userrecharges it. The computer will also registerregular periods of non-use, during which thebattery can be recharged. Secondary Ni-Cdbatteries are most appropriate for this usagepattern.

When a laptop-computer battery reaches theend of its life cycle, it should be replaced witha battery designed specifically for that laptopcomputer. Using other types of batteries maydamage the computer. The user’s manual forthe laptop computer will list one or morebattery types and brands that may be used. Ifin doubt, the user is advised to contact themanufacturer of the laptop computer and askfor a battery-replacement recommendation.

4.8 CAMCORDERS

Almost all commercial, off-the-shelfcamcorders come with a battery and arecharging unit when purchased.

The camcorder is typically operatedcontinuously for several minutes or hours (toproduce a video recording of some event).This use will require that the battery provideapproximately 2 hours of non-stop recordingtime. The electric motor driving the recordingtape through the camcorder requires amoderately high amount of power throughoutthe entire recording period.

Rechargeable Ni-Cd or Ni-MH batteries orprimary lithium batteries are usually the onlychoice for camcorder use. Several batterymanufacturers produce Ni-Cd or Ni-MH

18Easy to Choose, Easy to Use, EvereadyBattery Corporation, 1997.

19Cellular Duracell Rechargeable Batteries,Duracell, 1996.


29

batteries that are specially designed for use incamcorders. Due to the lack of sufficientstandardization for these kind of batteries, thebattery manufacturers must design and sellapproximately 20 different camcorderbatteries to fit at least 100 models ofcamcorders from over a dozenmanufacturers.20

Camcorder batteries are usually designed toprovide 2 hours of service, but larger batteriesare available that can provide up to 4 hours ofservice.

Lithium camcorder batteries can provide three to five times the energy of a single cycle ofsecondary Ni-Cd batteries. These lithiumbatteries, however, are primary batteries andmust be properly disposed of at the end oftheir life cycle. Secondary lithium-ioncamcorder batteries are being developed.

4.9 SUMMARY

There are six varieties of batteries in use, eachwith its own advantages and disadvantages.Below is a short summary of each variety:

_ Lead-Acid -- Secondary lead-acidbatteries are the most popular worldwide.Both the battery product and themanufacturing process are proven,economical, and reliable._ Nickel-Cadmium -- Secondary Ni-Cdbatteries are rugged and reliable. They exhibita high-power capability, a wide operatingtemperature range, and a long cycle life. Theyhave a self-discharge rate of approximately1% per day.

_ Alkaline -- The most commonly usedprimary cell (household) is the zinc-alkalinemanganese dioxide battery. They providemore power-per-use than secondary batteriesand have an excellent shelf life._ Rechargeable Alkaline -- Secondaryalkaline batteries have a long shelf life and areuseful for moderate-power applications. Theircycle life is less than most other secondarybatteries._ Lithium Cells -- Lithium batteries offerperformance advantages well beyond thecapabilities of conventional aqueouselectrolyte battery systems. However, lithiumbatteries are not widely used because of safetyconcerns._ Thermal Batteries -- These are specialbatteries that are capable of providing veryhigh rates of discharge for short periods oftime. They have an extremely long shelf life,but, because of the molten electrolyte and highoperating temperature, are impractical formost household uses.

20Camcorder Battery Pocket Guide, EvereadyBattery Company, 1996.


30

31

5. Battery Handling and Maintenance

The following guidelines offer specific adviceon battery handling and maintenance. Thisadvice is necessarily not all inclusive. Usersare cautioned to observe specific warnings onindividual battery labels and to use commonsense when handling batteries.

5.1 BATTERY DANGERS

8 To get help, should someone swallow abattery, immediately call The NationalBattery Ingestion Hot Line collect at(202) 625-3333. Or, call 911 or astate/local Poison Control Center.

8 Batteries made from lead (or other heavymetals) can be very large and heavyand can cause damage to equipment orinjuries to personnel if improperlyhandled.

8 When using lithium batteries, a “Lith-X”or D-Class fire extinguisher shouldalways be available. Water-basedextinguishers must not be used onlithium of any kind, since water willreact with lithium and release largeamounts of explosive hydrogen.

� Before abusively testing a battery, contactthe manufacturer of the battery toidentify any potential dangers.

8 Vented batteries must be properlyventilated. Inadequate ventilation mayresult in the build up of volatile gases,

which may result in an explosion orasphyxiation.

� Do not attempt to solder directly onto aterminal of the battery. Attempting todo so can damage the seal or the safetyvent.

� When disconnecting a battery from thedevice it is powering, disconnect oneterminal at a time. If possible, firstremove the ground strap at itsconnection with the device’sframework. Observing this sequencecan prevent an accidental short circuitand also avoid risking a spark at thebattery. In most late-model, domesticautomobiles, the battery terminallabeled “negative” is usually connectedto the automobile’s framework.

� Do not attempt to recharge primarybatteries. This kind of battery is notdesigned to be recharged and mayoverheat or leak if recharging isattempted.

8 When recharging secondary batteries, use acharging device that is approved forthat type of battery. Using an approvedcharging device can preventovercharging or overheating thebattery. Many chargers have specialcircuits built into them for correctlycharging specific types of batteries and


32

will not work properly with othertypes.

� Do not use secondary (rechargeable)batteries in smoke detectors.Secondary batteries have a high self-discharge rate. Primary batteries have amuch longer shelf life and are muchmore dependable in emergencies.Consult the smoke detector’s usermanual for the recommended batterytypes.

� Do not attempt to refill or repair a worn-outor damaged battery.

� Do not allow direct bodily contact withbattery components. Acidic or alkalineelectrolyte can cause skin irritation orburns. Electrode materials such asmercury or cadmium are toxic.Lithium can cause an explosion if itcomes into contact with water. Othercomponents can cause a variety ofshort-term (irritation and burns) orlong-term (nerve damage) maladies.

� Do not lick a 9 V battery to see if it ischarged. You will, of course, be able todetermine whether or not the battery ischarged, but such a test may result in aburn that may range from simplyuncomfortable to serious.

� Do not dispose of batteries in a fire. Themetallic components of the battery willnot burn and the burning electrolytemay splatter, explode, or release toxicfumes. Batteries may be disposed of,however, in industrial incinerators thatare approved for the disposal ofbatteries.

� Do not carry batteries in your pocket. Coins, keys, or other metal objects canshort circuit a battery, which can causeextreme heat, acid leakage, or anexplosion.

� Do not wear rings, metal jewelry, or metalwatchbands while handling chargedcells. Severe burns can result fromaccidentally short circuiting a chargedcell. Wearing gloves can reduce thisdanger.

� Do not use uninsulated tools near chargedcells. Do not place charged cells onmetal workbenches. Severe arcing andoverheating can result if the battery’sterminals are shorted by contact withsuch metal objects.


33

The Straight Dopeby Cecil Adams, The Chicago Reader

Is it true that refrigerating batteries willextend shelf life? If so, why does a cold carbattery cause slower starts? The answerwill help me sleep better. — Kevin C.,Alexandria, Virginia

Whatever it takes, dude. Refrigeratingbatteries extends shelf life because batteriesproduce electricity through a chemicalreaction. Heat speeds up any reaction, whilecold slows it down. Freeze your [carbattery] and you’ll extend its life becausethe juice won’t leak away—but it’ll alsomake those volts a little tough to use rightaway. That accounts for the beliefoccasionally voiced by mechanics that if abattery is left on the garage floor for anextended period, the concrete will “suckout the electricity.” It does nothing of thekind, but a cold floor will substantiallyreduce a battery’s output. The cure: warmit up first.

(Reprinted, with permission, from Return of the Straight Dope.©1994 Chicago Reader, Inc.)

5.2 EXTENDING BATTERY L IFE

8 Read the instructions for the device beforeinstalling batteries. Be sure to orientthe battery’s positive and negativeterminals correctly when insertingthem.

8 In a device, use only the type of batterythat is recommended by themanufacturer of the device.

8 To find a replacement battery that workswith a given device, call themanufacturer of the device or ask theretailer to check the manufacturer’sbattery cross-reference guide.

8 Store batteries in a cool, dark place. Thishelps extend their shelf life.Refrigerators are convenient locations.Although some battery manufacturerssay that refrigeration has no positiveeffect on battery life, they say it has nonegative effect either. Do not storebatteries in a freezer. Always letbatteries come to room temperaturebefore using them.

8 Store batteries in their original boxes orpackaging materials. The batterymanufacturer has designed thepackaging for maximum shelf life.

8 When storing batteries, remove any load orshort circuit from their terminals.

8 When storing battery-powered devices forlong periods (i.e., more than a month),remove the batteries. This can preventdamage to the device from possiblebattery leakage. Also, the batteries canbe used for other applications while thebatteries are still “fresh.”


34

8 Use a marking pen to indicate, on thebattery casing, the day and year that thebattery was purchased. Also, keeptrack of the number of times thebattery has been recharged. Avoidwriting on or near the batteryterminals.

8 Do not mix batteries from differentmanufacturers in a multi-cell device(e.g., a flashlight). Small differences involtage, current, and capacity, betweenbrands, can reduce the average usefullife of all the batteries.

8 When using secondary batteries in a multi-cell device (e.g., a flashlight), try touse batteries of the same age andsimilar charging histories. This kind ofmatching will make it more likely thatall the batteries will discharge at thesame rate, putting less stress on anyindividual battery.

8 When using single-cell rechargeable Ni-Cdbatteries, be sure to discharge the cellcompletely before recharging it, thuscounteracting the “memory” effect.

8 Secondary Ni-Cd batteries can sometimesbe reconditioned to reduce the impactof “memory” effects. Completelydischarge the battery and recharge itseveral times.

� Do not use batteries in high-temperaturesituations (unless the battery isdesigned for that temperature range).Locate batteries as far away from heatsources as possible. The electricalpotential of the battery will degraderapidly if it is exposed to temperatures

higher than those recommended by themanufacturer.

35

Description Charge Rate(Amperes)

Nominal ChargeTime (Hours)

Standby(Trickle)

0.01 C to 0.03 C 100 to 33

Slow(Overnight)

0.05 C to 0.1 C 20 to 10

Quick 0.2 C to 0.5 C 5 to 2

Fast 1 C and more 1 and less

“C” is the theoretical current needed to completelycharge the fully discharged battery in one hour.

Table 7. Charge Rate Descriptions

6. Battery Chargers and Adapters

6.1 BATTERY CHARGERS

Secondary (rechargeable) batteries require abattery charger to bring them back to fullpower. The charger will provide electricity tothe electrodes (opposite to the direction ofelectron discharge), which will reverse thechemical process within the battery,converting the applied electrical energy intochemical potential energy.

Batteries should only be recharged withchargers that are recommended, by themanufacturer, for that particular type ofbattery. In general, however, battery-industrystandards ensure that any off-the-shelf batterycharger, specified for one brand, size, and type

of battery, will be able to charge correctly anybrand of battery of that same size and type.

Do not, however, use a charger designed forone type of battery to charge a different type ofbattery, even if the sizes are the same. Forexample, do not use a charger designed forcharging “D”-sized Ni-Cd batteries to charge“D”-sized rechargeable alkaline batteries. If in

doubt, use only the exact chargerrecommended by the batterymanufacturer.

Recharging a battery without arecommended charger isdangerous. If too much current issupplied, the battery may overheat,leak, or explode. If not enoughcurrent is applied, the battery maynever become fully charged, sincethe self-discharge rate of thebattery will nullify the chargingeffort.

It is not recommended that batteryusers design and build their owncharging units. Many low-costchargers are available off-the-shelf

that do a good job of recharging batteries.Specific, off-the-shelf chargers are identifiedand recommended, by each of the majorbattery manufacturers, for each type ofsecondary battery they produce.


36

The key issue in charging a batteryis knowing when to stop charging.

6.2 CHARGE RATES

The current that a charger supplies to thebattery is normally expressed as a fraction ofthe theoretical current (for a given battery)needed to charge the battery completely in1 hour. This theoretical current is called thenominal battery capacity rating and isrepresented as “C.” For example, a current of0.1 C is that current which, in 10 hours,theoretically, would recharge the battery fully.Table 7 shows some common charging ratesfor various styles of recharging.

6.3 CHARGING TECHNIQUES

In general, lower charge rates will extend theoverall life of the battery. A battery can bedamaged or de-graded if too muchcurrent is appliedduring the chargingprocess. Also,when a battery is inthe final stages ofcharging, the current must be reduced toprevent damage to the battery. Many chargersoffer current-limiting devices that will shut offor reduce the applied current when the batteryreaches a certain percent of its chargedpotential.

Slow charge rates (between 0.05 C and 0.1 C)are the most-often recommended charge rate,since a battery can be recharged in less than aday, without significant probability ofdamaging or degrading the battery. Slowcharge rates can be applied to a battery for anindefinite period of time, meaning that thebattery can be connected to the charger fordays or weeks with no need for special shut-off or current-limiting equipment on thecharger.

Trickle chargers (charge rates lower than0.05 C) are generally insufficient to charge abattery. They are usually only applied after abattery is fully charged (using a greater chargerate) to help offset the self-discharge rate ofthe battery. Batteries on a trickle charger willmaintain their full charge for months at a time.It is usually recommended that batteries on atrickle charger be fully discharged andrecharged once every 6 to 12 months.

Quick and fast charging rates (over 0.2 C) canbe used to charge many kinds of secondarybatteries. In such cases, however, damage ordeterioration can occur in the battery if thesehigh charge rates are applied after the batteryhas approximately 85% of its charge restored.

Many quick andfast chargers willhave current-limiters built intothem that willslowly reduce thecurrent as the

battery is charged, thereby preventing most ofthis deterioration.

The recharge times shown in Table 7 may besomewhat lower than the actual times requiredto recharge batteries at the associated chargerates. Various elements, such as temperature,humidity, initial charge state, and the rechargehistory of the cell, will each act to extend thetime needed to charge the cell fully.

6.4 CHARGING LEAD-ACID BATTERIES

Constant potential charging, with currentlimiting, is usually recommended for sealedlead-acid cells. Due to the sloping voltageprofile of a lead-acid battery, the voltage ofthe battery is a reliable indicator of its state of


37

charge. Current limiting may be accomplishedthrough the use of a current-limiting resistor.One manufacturer uses a miniature light bulbas a current-limiting resistor. The brightnessof the bulb will provide a visual indication ofthe state of charge of the battery. In modernpractice, however, current limiting isaccomplished with integrated circuits.

6.5 CHARGING NI-CD BATTERIES

During their recharge cycle, nickel-cadmiumbatteries react in a manner different from otherbatteries. Nickel-cadmium batteries willactually absorb heat during the first 25% ofthe charge cycle (as opposed to mostsecondary batteries, which generate heat allthrough their recharge cycle). Beyond that firstquarter of the charge cycle, a Ni-Cd batterywill generate heat. If constant current isapplied past the point when the battery reachesapproximately 85% of its fully charged state,the excess heat will cause “thermal runaway”to occur. Under thermal runaway conditions,the excess heat in the battery will cause itsvoltage to drop. The drop in voltage will causethe charge rate to increase (according toOhm’s Law), generating more heat andaccelerating the cycle. The temperature andinternal pressure of the battery will continue torise until permanent damage results.

When using trickle or slow chargers to chargeNi-Cd batteries, the heat build-up is minimaland is normally dissipated by atmosphericconvection before thermal runaway can occur.Most chargers supplied with, or as a part of,rechargeable devices (sealed flashlights, mini-vacuums, etc.) are slow chargers.

Quick or fast battery chargers, designedespecially for Ni-Cd batteries, will usually

have a temperature sensor or a voltage sensorthat can detect when the battery is nearingthermal-runaway conditions. When near-runaway conditions are indicated, the chargerwill reduce or shut off the current entering thebattery.

6.6 TIMED -CHARGE CHARGING

Most charging methods, described so far inthis guide, allow the user to begin charging acell regardless of its current state of charge.One additional method can be used to chargeNi-Cd cells, but only if the cell is completelydischarged. It is called the timed-chargedmethod.

One characteristic of Ni-Cd cells is that theycan accept very large charge rates (as high as20 C), provided that the cell is not forced intoan overcharge condition.

The timed-charge charger will provide high-rate current to the cell for a very specificperiod. A timer will then cut off the chargingcurrent at the end of that period. Some cellscan be charged completely in as little as 10minutes (as opposed to 8 hours on a slowcharger).

Great care should be exercised when using atimed-charge charger, because there is noroom for error. If the cell has any charge in itat all at the beginning of the charge cycle, or ifthe cell’s capacity is less than anticipated, thecell can quickly reach the fully charged state,proceed into thermal-runaway conditions, andcause the explosion or destruction of the cell.

Some timed-charge chargers have a specialcircuit designed to discharge the cellcompletely before charging it. These are


38

called dumped timed-charge chargers, sincethey dump any remaining charge beforeapplying the timed charge.

6.7 PULSED CHARGE-DISCHARGE

CHARGERS

This method of charging Ni-Cd cells applies arelatively high charge rate (approximately 5 C)until the cell reaches a voltage of 1.5 V. Thecharging current is then removed and the cellis rapidly discharged for a brief period of time(usually a few seconds). This actiondepolarizes the cell components and dissipatesany gaseous buildup within the cell. The cell isthen rapidly charged back to 1.5 V. Theprocess is repeated several more times untilthe cell’s maximum charge state is reached.

Unfortunately, this method has somedifficulties. The greatest difficulty is that themaximum voltage of a Ni-Cd cell will varywith several outside factors such as the cell’srecharge history and the ambient temperatureat the charger’s location. Since the cell’smaximum potential voltage is variable, thelevel to which it must be charged is alsovariable. Integrated circuits are beingdesigned, however, that may compensate forsuch variations.

6.8 CHARGING BUTTON BATTERIES

Secondary cylindrical (household) cells willusually have a safety seal or vent built intothem to allow excess gases, created during thecharging process, to escape. Secondary,button-type batteries do not have such sealsand are often hermetically sealed.

When cylindrical cells are overcharged, excessgases are vented. If a button battery isinadvertently overcharged, the excess gases

cannot escape. The pressure will build up andwill damage the battery or cause an explosion.Care should be taken not to overcharge asecondary button battery.

6.9 INTERNAL CHARGERS

For some applications, the charger may beprovided, by the battery manufacturer, as anintegral part of the battery itself. This designhas the obvious advantage of ensuring that thecorrect charger is used to charge the battery,but this battery-charger combination mayresult in size, weight and cost penalties for thebattery.

6.10 BATTERY TESTERS

A battery tester is a device that contains asmall load and attaches across the terminals ofa battery to allow the user to see if the batteryis sufficiently charged. A simple battery testercan be made from a flashlight bulb and twopieces of wire. Flashlight bulbs are ideal fortesting household batteries, since the voltageand current required to light the bulb is thesame as that of the battery. This kind offlashlight-bulb tester can also be used to draina secondary battery safely before fullycharging it.

Some off-the-shelf household batteries aresold with their own testers. These testers areattached to the packaging material or to thebattery itself. The active conductor in thetester is covered by a layer of heat-sensitiveink. As the ends of the tester are pressedagainst the battery terminals, a small amountof current will flow through the material underthe ink, heating it. The heating will cause theink to change color, indicating that the batterystill has energy.


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Using a simple battery tester to test a Ni-Cdbattery can be somewhat misleading, since aNi-Cd battery has a flat voltage profile. Thetester will indicate near-maximum voltagewhether the battery is 100% charged or 85%discharged.

6.11 “SMART ” BATTERIES

Many battery-powered devices require the useof multi-cell battery packs (i.e., severalordinary battery cells strapped together to beused as a single unit). The individual cellscannot be charged or measured separately,without destroying the battery pack.

A new development in rechargeable batterytechnology is the use of microelectronics inbattery-pack cases to create “intelligent”battery packs. These “smart” battery packscontain a microprocessor, memory, andsensors that monitor the battery’s temperature,voltage, and current. This information can berelayed to the device (if the device is designedto accept the information) and used tocalculate the battery’s state of charge at anytime or to predict how much longer the devicecan operate. The microprocessor on a batterypack may also record the history of the batteryand display the dates and number of times thatit has been charged.

To get the maximum potential from asecondary battery, the user must adopt a strictregimen of noting certain information aboutthe battery and acting upon that information.For example, if a battery is already partiallydischarged, using it in a device will obviouslynot allow the device to be used for its entireduty cycle. Attempting to charge a batterywhen the ambient temperature is too high isanother example of suboptimal battery usage,

since the battery will not hold as much chargeas it would have had it been charged at therecommended temperature.

Most battery users are not sufficiently diligentin matters of battery maintenance. “Smart”batteries allow the battery itself to record allpertinent information and make it available tothe user at a glance.

6.12 END OF L IFE

All secondary batteries will eventually fail dueto age, expended components, or physicaldamage. A battery, when properly maintained,will fail through gradual loss of capacity. Tothe user, this gradual failure will appear as afrequent need to change and charge thebatteries. Sudden failure, usually due tophysical abuse, will prevent the battery fromholding any charge at all.

The physical manifestations of a gradualfailure of the battery can be seen as adegradation of the separator material, dendriticgrowth or other misshapening of theelectrodes, and permanent material loss of theactive components.

The physical manifestations of a suddenfailure, can be seen as the destruction of thebattery components. Open-circuit failure canbe induced by an applied shock to or excessvibration of the battery. As a result, theinternal components of the battery maybecome loose or detached, causing a gap in theelectrical circuit.

Short-circuit failure can be caused by anapplied shock. It can also be caused byoverheating or overcharging the battery. In ashort-circuit failure, some part of one of the


40

electrodes pierces (caused by shock) or growsthrough (caused by overcharging) theseparator material in the electrolyte. Thispiercing effect will cause the electrical path tobe shorted.

If a battery and its replacements seem to besuffering repeated premature failures, inreoccurring and similar circumstances, thefailed batteries should be sent to a laboratoryfor dissection and analysis. The problem maylie in faulty equipment, inappropriate batteryusage, or in physical abuse to the device andits batteries. Resolution of the problem willsave time and money in future battery designsand applications.

6.13 BATTERY ADAPTERS

A battery adapter is a device that can be usedinstead of a battery to provide current to abattery-powered device.

Most battery adapters will convert 60 Hz, 110 V, alternating current (i.e., typical housecurrent) into direct current (dc) for use bybattery-powered devices. Other adapters aredesigned to be powered by 12 V automobilebatteries, usually by insertion of a plug intothe automobile’s cigarette lighter.

An adapter will usually have a dc-output plugthat is inserted into the battery-powered deviceto provide dc current to the device.

Usually, manufacturers of the more expensivebattery-powered devices (e.g., cellular phones,laptop computers) will provide the customerwith a battery adapter designed especially forthat device. The adapter will plug into aspecial connector in the device to provide itpower. If designed to do so, the battery adapterwill charge the device’s batteries as well.

Other manufacturers make generic batteryadapters. These adapters will have a battery-shaped appendage that plugs into a battery-powered device in place of a real battery andwill provide energy equivalent to a realbattery. While this kind of adapter has someadvantages (it can be used for any batterypowered device, it can be used when nocharged batteries are available, etc.), thoseadvantages are usually outweighed by thedisadvantages (the power cord is inconvenientand negates the portability of the device, thebattery cover cannot be replaced while thecord is attached, a multiple-battery devicewould require multiple adapters, etc.).

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Battery Manufacturers Web Address

Battery Engineering http://www.batteryeng.com/

Duracell Batteries http://www.duracell.com/

Eveready Batteries http://www.eveready.com/

Kodak Corporation http://www.kodak.com/

NEXcell http://www.battery.com.tw/

Panasonic Batteries http://www.panasonic-batteries.be/home.html

PolyStor Corporation http://www.polystor.com/

Radio Shack http://www.radioshack.com/

Rayovac Batteries http://www.rayovac.com/

Sony Corporation http://www.sel.sony.com/SEL/rmeg/batteries/

Battery Distributors Web Address

Battery-Biz, Inc. http://www.battery-biz.com/battery-biz/

Battery Depot http://www.battery-depot.com/

Battery Network http://batnetwest.com/

Batteries Plus http://www.spromo.com/battplus/

E-Battery http://e-battery.com/

Powerline http://www.powerline-battery.com/

All Web information was verified in August, 1997.

Table 8. Some On-Line Information Available via the World Wide Web

7. Products and Suppliers

Batteries andbatterymanufacturers andsuppliers listed ormentioned in thissection, andelsewhere in thisguideline, are listed for the convenienceof the reader. Thename of a specificproduct orcompany does notimply that theproduct orcompany is,necessarily, the bestfor any particularapplication ordevice. The listsare, necessarily, notall-inclusive. Thelist of Web pageswas compiledfollowing a Websearch performed inAugust, 1997. NewWeb pages mayhave appearedsince then andsome which appear in this list may no longerbe available. Other Web pages, that were notlisted in the Web-search database at that time,will also not appear in this list.

7.1 BATTERY MANUFACTURERS

The battery manufacturers listed below aresome of the manufacturers of householdbatteries. They are presented in alphabetical


42

order. All information was verified in August,1997.

7.1.1 Battery EngineeringPostal Address:

Battery Engineering, Inc.100 Energy DriveCanton, MA 02001

Phone Number:(617) 575-0800

Web Page:http://www.batteryeng.com

Email Address:[email protected]

7.1.2 DuracellPostal Address:

Duracell, Inc.Berkshire Corp ParkBethel, CT 06801

Phone Number:1 (800) 551-2355

Web Page:http://www.duracell.com/

7.1.3 EvereadyPostal Address:

Eveready Battery Company, Inc.Checkerboard SquareSt. Louis, MO 63164-0001

Phone Number:1 (800) 383-7323

Web Page:http://www.eveready.com/


7.1.4 RayovacPostal Address:

Rayovac CorporationP.O. Box 44960Madison, WI 53744-4960

Phone Number:1 (800) 237-7000

Web Page:http://www.rayovac.com/


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8. A Glossary of Battery Terms

2 Ampere-Hour -- One ampere-hour isequal to a current of one ampereflowing for one hour. A unit-quantityof electricity used as a measure of theamount of electrical charge that may beobtained from a storage battery beforeit requires recharging.

2 Ampere-Hour Capacity -- The number ofampere-hours which can be deliveredby a storage battery on a singledischarge. The ampere-hour capacityof a battery on discharge is determinedby a number of factors, of which thefollowing are the most important: finallimiting voltage; quantity ofelectrolyte; discharge rate; density ofelectrolyte; design of separators;temperature, age, and life history of thebattery; and number, design, anddimensions of electrodes.

2 Anode -- In a primary or secondary cell,the metal electrode that gives upelectrons to the load circuit anddissolves into the electrolyte.

2 Aqueous Batteries -- Batteries with water-based electrolytes.

2 Available Capacity -- The total batterycapacity, usually expressed in ampere-hours or milliampere-hours, availableto perform work. This depends onfactors such as the endpoint voltage,quantity and density of electrolyte,

temperature, discharge rate, age, andthe life history of the battery.

2 Battery -- A device that transformschemical energy into electric energy.The term is usually applied to a groupof two or more electric cells connectedtogether electrically. In common usage,the term “battery” is also applied to asingle cell, such as a householdbattery.

2 Battery Types -- There are, in general,two type of batteries: primary batteries,and secondary storage or accumulatorbatteries. Primary types, althoughsometimes consisting of the sameactive materials as secondary types, areconstructed so that only onecontinuous or intermittent dischargecan be obtained. Secondary types areconstructed so that they may berecharged, following a partial orcomplete discharge, by the flow ofdirect current through them in adirection opposite to the current flowon discharge. By recharging afterdischarge, a higher state of oxidation iscreated at the positive plate orelectrode and a lower state at thenegative plate, returning the plates toapproximately their original chargedcondition.

2 Battery Capacity -- The electric output ofa cell or battery on a service test


44

delivered before the cell reaches aspecified final electrical condition andmay be expressed in ampere-hours,watt-hours, or similar units. Thecapacity in watt-hours is equal to thecapacity in ampere-hours multiplied bythe battery voltage.

2 Battery Charger -- A device capable ofsupplying electrical energy to a battery.

2 Battery-Charging Rate -- The currentexpressed in amperes at which astorage battery is charged.

2 Battery Voltage, final -- The prescribedlower-limit voltage at which batterydischarge is considered complete. Thecutoff or final voltage is usuallychosen so that the useful capacity ofthe battery is realized. The cutoffvoltage varies with the type of battery,the rate of discharge, the temperature,and the kind of service in which thebattery is used. The term “cutoffvoltage” is applied more particularly toprimary batteries, and “final voltage”to storage batteries. Synonym:Voltage, cutoff.

2 Ci -- The rated capacity, in ampere-hours,for a specific, constant dischargecurrent (where i is the number of hoursthe cell can deliver this current). Forexample, the C5 capacity is theampere-hours that can be delivered bya cell at constant current in 5 hours. Asa cell’s capacity is not the same at allrates, C5 is usually less than C20 for thesame cell.

2 Capacity -- The quantity of electricitydelivered by a battery under specifiedconditions, usually expressed inampere-hours.

2 Cathode -- In a primary or secondary cell,the electrode that, in effect, oxidizesthe anode or absorbs the electrons.

2 Cell -- An electrochemical device,composed of positive and negativeplates, separator, and electrolyte,which is capable of storing electricalenergy. When encased in a containerand fitted with terminals, it is the basic“building block” of a battery.

2 Charge -- Applied to a storage battery, theconversion of electric energy intochemical energy within the cell orbattery. This restoration of the activematerials is accomplished bymaintaining a unidirectional current inthe cell or battery in the oppositedirection to that during discharge; acell or battery which is said to becharged is understood to be fullycharged.

2 Charge Rate -- The current applied to asecondary cell to restore its capacity.This rate is commonly expressed as amultiple of the rated capacity of thecell. For example, the C/10 charge rateof a 500 Ah cell is expressed as,

C/10 rate = 500 Ah / 10 h = 50 A.

2 Charge, state of -- Condition of a cell interms of the capacity remaining in thecell.


45

2 Charging -- The process of supplyingelectrical energy for conversion tostored chemical energy.

2 Constant-Current Charge -- A chargingprocess in which the current of astorage battery is maintained at aconstant value. For some types of lead-acid batteries this may involve tworates called the starting and finishingrates.

2 Constant-Voltage Charge -- A chargingprocess in which the voltage of astorage battery at the terminals of thebattery is held at a constant value.

2 Cycle -- One sequence of charge anddischarge. Deep cycling requires thatall the energy to an end voltageestablished for each system be drainedfrom the cell or battery on eachdischarge. In shallow cycling, theenergy is partially drained on eachdischarge; i.e., the energy may be anyvalue up to 50%.

2 Cycle Life -- For secondary rechargeablecells or batteries, the total number ofcharge/discharge cycles the cell cansustain before it becomes inoperative.In practice, end of life is usuallyconsidered to be reached when the cellor battery delivers approximately 80%of rated ampere-hour capacity.

2 Depth of Discharge -- The relativeamount of energy withdrawn from abattery relative to how much could bewithdrawn if the battery weredischarged until exhausted.

2 Discharge -- The conversion of thechemical energy of the battery intoelectric energy.

2 Discharge, deep -- Withdrawal of allelectrical energy to the end-pointvoltage before the cell or battery isrecharged.

2 Discharge, high-rate -- Withdrawal oflarge currents for short intervals oftime, usually at a rate that wouldcompletely discharge a cell or batteryin less than one hour.

2 Discharge, low-rate -- Withdrawal ofsmall currents for long periods of time,usually longer than one hour.

2 Drain -- Withdrawal of current from acell.

2 Dry Cell -- A primary cell in which theelectrolyte is absorbed in a porousmedium, or is otherwise restrainedfrom flowing. Common practice limitsthe term “dry cell” to the Leclanchécell, which is the common commercialtype.

2 Electrochemical Couple -- The system ofactive materials within a cell thatprovides electrical energy storagethrough an electrochemical reaction.

2 Electrode -- An electrical conductorthrough which an electric currententers or leaves a conducting medium,whether it be an electrolytic solution,solid, molten mass, gas, or vacuum.For electrolytic solutions, many solids,and molten masses, an electrode is an


46

electrical conductor at the surface ofwhich a change occurs fromconduction by electrons to conductionby ions. For gases and vacuum, theelectrodes merely serve to conductelectricity to and from the medium.

2 Electrolyte -- A chemical compoundwhich, when fused or dissolved incertain solvents, usually water, willconduct an electric current. Allelectrolytes in the fused state or insolution give rise to ions whichconduct the electric current.

2 Electropositivity -- The degree to whichan element in a galvanic cell willfunction as the positive element of thecell. An element with a largeelectropositivity will oxidize fasterthan an element with a smallerelectropositivity.

2 End-of-Discharge Voltage -- The voltageof the battery at termination of adischarge.

2 Energy -- Output capability; expressed ascapacity times voltage, or watt-hours.

2 Energy Density -- Ratio of cell energy toweight or volume (watt-hours perpound, or watt-hours per cubic inch).

2 Float Charging -- Method of rechargingin which a secondary cell iscontinuously connected to a constant-voltage supply that maintains the cellin fully charged condition.

2 Galvanic Cell -- A combination ofelectrodes, separated by electrolyte,

that is capable of producing electricalenergy by electrochemical action.

2 Gassing -- The evolution of gas from oneor both of the electrodes in a cell.Gassing commonly results from self-discharge or from the electrolysis ofwater in the electrolyte duringcharging.

2 Internal Resistance -- The resistance tothe flow of an electric current withinthe cell or battery.

2 Memory Effect -- A phenomenon inwhich a cell, operated in successivecycles to the same, but less than full,depth of discharge, temporarily losesthe remainder of its capacity at normalvoltage levels (usually applies only toNi-Cd cells).

2 Negative Terminal -- The terminal of abattery from which electrons flow inthe external circuit when the celldischarges. See Positive Terminal.

2 Nonaqueous Batteries -- Cells that do notcontain water, such as those withmolten salts or organic electrolytes.

2 Ohm’s Law -- The formula that describesthe amount of current flowing througha circuit.Voltage = Current × Resistance.

2 Open Circuit -- Condition of a batterywhich is neither on charge nor ondischarge (i.e., disconnected from acircuit).


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2 Open-Circuit Voltage -- The difference inpotential between the terminals of acell when the circuit is open (i.e., a no-load condition).

2 Oxidation -- A chemical reaction thatresults in the release of electrons by anelectrode’s active material.

2 Parallel Connection -- The arrangementof cells in a battery made byconnecting all positive terminalstogether and all negative terminalstogether, the voltage of the group beingonly that of one cell and the currentdrain through the battery being dividedamong the several cells. See SeriesConnection.

2 Polarity -- Refers to the charges residingat the terminals of a battery.

2 Positive Terminal -- The terminal of abattery toward which electrons flowthrough the external circuit when thecell discharges. See NegativeTerminal .

2 Primary Battery -- A battery made up ofprimary cells. See Primary Cell .

2 Primary Cell -- A cell designed toproduce electric current through anelectrochemical reaction that is notefficiently reversible. Hence the cell,when discharged, cannot be efficientlyrecharged by an electric current.Note: When the available energy dropsto zero, the cell is usually discarded.Primary cells may be further classifiedby the types of electrolyte used.

2 Rated Capacity -- The number of ampere-hours a cell can deliver under specificconditions (rate of discharge, endvoltage, temperature); usually themanufacturer’s rating.

2 Rechargeable -- Capable of beingrecharged; refers to secondary cells orbatteries.

2 Recombination -- State in which the gasesnormally formed within the battery cellduring its operation, are recombined toform water.

2 Reduction -- A chemical process thatresults in the acceptance of electronsby an electrode’s active material.

2 Seal -- The structural part of a galvaniccell that restricts the escape of solventor electrolyte from the cell and limitsthe ingress of air into the cell (the airmay dry out the electrolyte or interferewith the chemical reactions).

2 Secondary Battery -- A battery made upof secondary cells. See StorageBattery; Storage Cell.

2 Self Discharge -- Discharge that takesplace while the battery is in an open-circuit condition.

2 Separator -- The permeable membranethat allows the passage of ions, butprevents electrical contact between theanode and the cathode.

2 Series Connection -- The arrangement ofcells in a battery configured byconnecting the positive terminal of


48

each successive cell to the negativeterminal of the next adjacent cell sothat their voltages are cumulative. SeeParallel Connection.

2 Shelf Life -- For a dry cell, the period oftime (measured from date ofmanufacture), at a storage temperatureof 21(C (69(F), after which the cellretains a specified percentage (usually90%) of its original energy content.

2 Short-Circuit Current -- That currentdelivered when a cell is short-circuited(i.e., the positive and negativeterminals are directly connected with alow-resistance conductor).

2 Starting-Lighting-Ignition (SLI)Battery -- A battery designed to startinternal combustion engines and topower the electrical systems inautomobiles when the engine is notrunning. SLI batteries can be used inemergency lighting situations.

2 Stationary Battery -- A secondary batterydesigned for use in a fixed location.

2 Storage Battery -- An assembly ofidentical cells in which theelectrochemical action is reversible sothat the battery may be recharged bypassing a current through the cells inthe opposite direction to that ofdischarge. While many non-storagebatteries have a reversible process,only those that are economicallyrechargeable are classified as storagebatteries. Synonym: Accumulator;Secondary Battery. See SecondaryCell.

2 Storage Cell -- An electrolytic cell for thegeneration of electric energy in whichthe cell after being discharged may berestored to a charged condition by anelectric current flowing in a directionopposite the flow of current when thecell discharges. Synonym: SecondaryCell. See Storage Battery.

2 Taper Charge -- A charge regimedelivering moderately high-ratecharging current when the battery is ata low state of charge and tapering thecurrent to lower rates as the batterybecomes more fully charged.

2 Terminals -- The parts of a battery towhich the external electric circuit isconnected.

2 Thermal Runaway -- A conditionwhereby a cell on charge or dischargewill destroy itself through internal heatgeneration caused by high overchargeor high rate of discharge or otherabusive conditions.

2 Trickle Charging -- A method ofrecharging in which a secondary cell iseither continuously or intermittentlyconnected to a constant-current supplythat maintains the cell in fully chargedcondition.

2 Vent -- A normally sealed mechanism thatallows for the controlled escape ofgases from within a cell.

2 Voltage, cutoff -- Voltage at the end ofuseful discharge. (See Voltage, end-point.)


49

2 Voltage, end-point -- Cell voltage belowwhich the connected equipment willnot operate or below which operationis not recommended.

2 Voltage, nominal -- Voltage of a fullycharged cell when delivering ratedcurrent.

2 Wet Cell -- A cell, the electrolyte of whichis in liquid form and free to flow andmove.


50

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9. Bibliography

American National Standard Specification forDry Cells and Batteries, AmericanNational Standards Institutes, Inc.ANSI C18.1M-1992.

Application Notes & Product Data Sheet:Primary Batteries—Alkaline, HeavyDuty & General Purpose, RayovacCorporation, January 1996.

Batteries Used with Law EnforcementCommunications Equipment: Chargersand Charging Techniques, W.W.Scott, Jr., U.S. Department of Justice,LESP-RPT-0202.00, June 1973.

Batteries Used with Law EnforcementCommunications Equipment:Comparison and PerformanceCharacteristics, R.L. Jesch and I.S.Berry, U.S. Department of Justice,LESP-RPT-0201.00, May 1972.

Battery Engineering Web Site,http://www.batteryeng.com, August1997.

Battery Selection & Care, Eveready BatteryCorporation, 1995.

Camcorder Battery Pocket Guide, EvereadyBattery Corporation, Inc., 1996.

Cellular Duracell Rechargeable Batteries,Duracell, 1996.

Design Note: Renewal Reusable AlkalineBatteries Applications and SystemDesign Issues For Portable ElectronicEquipment, Rayovac Corporation,presented at: Portable by DesignConference, 1995.

Duracell Batteries Web Site,http://www.duracell.com, August1997.

Easy to Choose, Easy to Use, EvereadyBattery Corporation, 1997.

Encyclopedia of Physical Science andTechnology, Brooke Schumm, Jr.,1992.

Eveready and the Environment, EvereadyBattery Company, Inc., 1995.

Eveready Batteries Web Site,http://www.eveready.com, August1997.

Household Batteries and the Environment,Rayovac Corporation, 1995.

How to Choose, Use, Care For, and Disposeof Batteries, Electronics IndustriesAssociation Consumer ElectronicsGroup, 1992.


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Land Mobile FM or PM CommunicationsEquipment, Measurement andPerformance Standard, ElectronicsIndustry Association/Telecommunications IndustryAssociation, Publication EIA/TIA 603,1993.

Minimum Standards for Portable/PersonalLand Mobile Communications FM orPM Equipment 25-470 MC,Electronics Industries Association,EIA/TIA-316-C-1989.

Navy Primary and Secondary Batteries.Design and Manufacturing Guidelines,NAVSO P-3676, September 1991.

Panasonic Batteries Web Site,http://www.panasonic-batteries.be/home.html, August 1997.

PolyStor Web Page, http://www.polystor.com, August,1997.

Rayovac Batteries Web Site,http://www.rayovac.com, August1997.

Rechargeable Batteries for Personal/PortableTransceivers, National Institute ofJustice, NIJ Standard-0211.01,September, 1995.

Return of the Straight Dope, Cecil Adams,Chicago Reader, 11 East IllinoisStreet, Chicago, IL 60611, 1994.

Supervisory ICs Empower Batteries to TakeCharge, Bill Schweber, EDN, CahnersPublishing Company, 8773 SouthRidgeline Blvd., Highlands Ranch, CO80126-2329, September 1, 1997.

Telephony’s Dictionary, second edition, April1986. Graham Langley, TelephonyPublishing Corp.

The Eveready Battery Story, Eveready BatteryCompany, Inc., 1995.

The Story of Packaged Power, DuracellInternational, Inc., July, 1995.

Van Nostrand’s Scientific Encyclopedia, SixthEdition, Douglas M Considine, Editor,1983.

What is a Battery?, Rayovac Corporation,1995.

Why Use Energizer AA Lithium Batteries?,Eveready Battery Company, Inc., 1993.

Documents

JUST I C E National Institute of Justice