ACTIVATION – The process of wetting the cell with electrolyte, followed by the charging or formation process to prepare the cell or battery for use.
ACTIVATION TIME – The time interval from the moment activation is initiated to the moment the desired operating voltage is obtained in a cell or battery.
ALKALINE CELL – An electrochemical cell that uses an alkaline solution, usually potassium hydroxide (KOH), as the electrolyte.
AMPERE-HOUR – A current of 1 ampere flowing for 1 hour. Multiplying the current in amperes by the time of flow in hours gives the total number of ampere-hours.
AMPERE-HOUR CAPACITY – A measure of the energy content of a battery. It is computed by multiplying the number of amperes flowing from a cell or battery on discharge, at a given temperature and down to a specified endpoint voltage, by the time in hours the cell or battery will deliver the amperes of current.
ANODE – The negative electrode of a non-rechargeable (primary) cell at which an oxidation reaction (loss of electrons) occurs. In rechargeable (secondary) cells, either electrode may become the anode, depending upon direction of current flow.
BAFFLE – A nonconductive barrier inserted in the cell above the plate pack and used as a reference for the electrolyte level. It also protects the top edges of the plates from objects dropped into the vent cap hole.
BATTERY – A combination of two or more chemical cells electrically connected to work together to produce electric energy. (Common usage permits this designation to be applied also to a single cell used independently.)
C-RATE – Discharge or charge current rate in amperes; numerically equal to rated capacity of a cell in ampere hours.
CADMIUM ELECTRODE – See NEGATIVE PLATE.
CAPACITY – See AMPERE-HOUR CAPACITY.
CAPACITY, FUNCTIONAL LOSS OF – Reduction in cell capacity due to nonstandard charging or discharging parameters such as cell temperature, current, and discharge voltage cutoff. See also FAILURE, FUNCTIONAL.
CAPACITY, NAMEPLATE – See CAPACITY, RATED.
CAPACITY, NOMINAL – See CAPACITY, RATED.
CAPACITY, PERMANENT LOSS OF – Reduction in cell capacity from .as new. value, under standard rating conditions, not recoverable by reconditioning. See also FAILURE, PERMANENT.
CAPACITY, RATED – A designation by the battery manufacturer which helps identify a particular cell model and also provides an approximation of capacity; usually expressed in ampere-hours at a given discharge current.
CAPACITY, RESIDUAL – Capacity remaining at a particular point in time after any set of operating conditions, usually including a partial discharge or long rest.
CAPACITY, RESTORABLE – See CAPACITY, TEMPORARY LOSS OF.
CAPACITY, TEMPORARY LOSS OF – Reduction in cell capacity that is recovered when the cell is subjected to several reconditioning cycles.
CAPACITY, USEFUL – See AMPERE-HOUR CAPACITY.
CAPACITY RECONDITIONING – See RECONDITIONING
CASE – The battery box or enclosure which contains the cells and associated connectors and hardware.
CASE LINERS – Sheets of nonconductive materials inserted between cells and battery case that serve as insulators.
CATHODE – The positive electrode of a non-rechargeable (primary) cell at which a reduction reaction (gain of electrons) occurs. In rechargeable (secondary) cells, either electrode may become the cathode, depending upon direction of current flow.
CELL – An electrochemical device composed of positive and negative plates, separator, and electrolyte which is capable of storing electrical energy. When encased in a container and fitted with terminals, it is the basic building block of the battery.
CELL PULLER – A specially-designed strap used to remove cells from a battery.
CELL REVERSAL – Reversing of polarity of terminals of a cell in a multi-cell battery due to excessive discharge.
CHARGE – The electrical energy stored in a battery or cell.
CHARGE, STATE OF – The condition of a storage cell or battery in terms of the remaining capacity.
CHARGE RETENTION – The tendency of a charged cell to resist self-discharge.
CHARGER – Device capable of supplying electrical energy to a battery.
CHARGING – The process of converting electrical energy to stored chemical energy.
CHARGING EFFICIENCY – Ratio of the capacity delivered on discharge, after being fully charged, to the capacity needed to restore full charge to the cell or battery.
CONNECTOR – An electrically conductive bar or wire which joins individual cells together in a battery.
CONSTANT CURRENT – Charging method in which current does not change appreciably in magnitude, regardless of battery voltage or temperature.
CONSTANT POTENTIAL – Charging method which applies a fixed voltage to a cell. Often abbreviated CP.
CONTAINER – The cell enclosure in which the plates, separator and electrolyte are held. It is made up of the cell jar and cover that are permanently joined.
CONTAMINANT – Undesirable element, usually in the electrolyte, which reduces the capability of the cell. In vented cells, contaminants can be introduced by use of tap water or operation without vent cap.
COULOMETER – Electrochemical or electronic device, capable of integrating current time, used for charge control.
COVER GASKET – The gasket that is attached to the inside of the battery cover. In many applications, it has raised portions to support the cells during axis inversion or vibration of the battery.
CURRENT DENSITY – The amount of electric current passing through a given cross-sectional area of a conductor in amperes per square inch, – i.e., the ratio of the current in amperes to the cross-sectional area of the conductor.
CUTOFF VOLTAGE – See END-POINT VOLTAGE.
CYCLE – One sequence of charge and discharge.
CYCLE LIFE – For secondary (rechargeable) cells or batteries, the total number of charge/discharge cycles before the cell or battery becomes inoperative.
CYLINDRICAL CELL – A cylinder-shaped sealed wound cell containing a high-pressure safety vent.
DEEP DISCHARGE – Withdrawal of all electrical energy to the end-point voltage before the cell or battery is recharged.
DEIONIZED WATER – Water which has been freed of ions by treatment with ion exchange resins.
DEPTH OF DISCHARGE – The proportion of the nominal capacity removed from a cell or battery during each discharge portion of a cycle, expressed in percent. Shallow depths of discharge are considered as less than 50 percent deep depths of discharge are considered greater than 50 percent.
DISCHARGE – The process of converting chemical energy into electrical energy.
DISCHARGE RATE – Current flow required to discharge a cell or battery to a specified cutoff or end-point voltage in a specified period of time. In general, it is the ratio of the nominal rated capacity divided by the specified time of discharge in hours and is expressed in amperes. (Campere-hours Thours = Iamperes).
DISTILLED WATER – Water which has been freed of ions by a process of vaporization and subsequent condensation.
DRAIN DISCHARGE – Withdrawal of all charge capacity from a cell or battery at a reduced current rate after the cell or battery has been partially discharged at a higher current rate.
DRY – Indication that the electrolyte in a cell is immobilized, either in the form of a paste or gel or absorbed in the separator material.
DRY CHARGE – Process by which the electrodes are formed and assembled in a cell in a charged state. The cell is activated when the electrolyte is added; after a soaking period, it is ready for discharge.
DRY SHELF LIFE – The period of time that a cell or battery can stand without electrolyte before deteriorating beyond a point where a specified capacity or voltage level can no longer be obtained, when packed and stored according to specifications.
DUTY CYCLE – The conditions and usage to which a battery is subjected during operation, consisting of charge, overcharge and discharge.
EFFECTIVE INTERNAL RESISTANCE, Re – The apparent opposition to current flow within a battery that manifests itself as a drop in battery voltage proportional to the discharge current. Its value depends on battery design, state of charge, temperature, and age.
ELECTRODE – Conducting body in which active materials are placed and through which current enters or leaves cell.
ELECTROLYTE – The chemical solution, usually acid or alkaline, that permits ionic conduction between anode and cathode or that takes part in the chemical reaction in the cell.
END-OF-DISCHARGE VOLTAGE – The voltage of the battery at termination of a discharge but before the discharge is stopped.
END-POINT VOLTAGE – Cell or battery voltage at which point rated discharge capacity has been delivered at a specified rate of discharge. Also used to specify the cell or battery voltage below which the connected equipment will not operate or below which operation is not recommended. Sometimes called cutoff voltage.
ENERGY – Cell or battery output capability, expressed as capacity times voltage, or watt-hours (W-hr).
ENERGY CONVERSION – The change from chemical to electrical energy within the cell, or the reverse.
ENERGY DENSITY – The ratio of cell or battery energy to either the weight (Wh/lb or Wh/kg) or the volume (Wh/L or Wh/cu.in.).
ENTRAINMENT – The process whereby gases generated in the cell carry electrolyte through the vent cap.
ENVIRONMENTAL CONDITIONS – External circumstances to which a cell or battery may be subjected, such as ambient temperature, humidity, shock, vibration, and altitude.
EQUALIZATION – See RECONDITIONING
EQUALIZATION CHARGE – A maintenance procedure consisting of a sustained constant current charge used to correct cell imbalance.
EQUALIZATION DISCHARGE – A maintenance procedure consisting of a deep discharge used to correct cell imbalance.
FAILURE, FUNCTIONAL – Condition in which the battery has caused the end-use device to fail to function at the performance level expected.
FAILURE, PERMANENT – A condition which does not permit a cell or battery to be reconditioned or restored to an acceptable performance level.
FAILURE, REVERSIBLE – Failure condition which may be corrected through the application of certain electrical procedures.
FAST CHARGING – Rapid return of energy to a battery at the C rate or more.
FLOAT CHARGING – The method of charging a cell or battery in which it is continuously connected to a constant voltage charging source that maintains the cell or battery in a fully charged condition.
FLOODED CELL – See VENTED CELL.
FLOODING – Filling of pores of a porous electrode with electrolyte solution, thereby preventing access of gases to electrode surface.
HARDWARE – A general term used to identify the screws, washers, nuts, etc., used for battery assembly.
HIGH-RATE DISCHARGE – Withdrawal of large amounts of current for short intervals of time from a cell or battery, usually at a rate that will completely discharge a cell or battery in less than 1 hour.
INTERNAL RESISTANCE – Opposition (ohmic resistance) to current flow within the cell or battery offered by the electrolyte, electrodes, and separator materials.
ION – In an electrolyte, an electrified component of a radical or molecule formed by the dissolution of an electrolyte forming positively charged cations and negatively charged anions.
JAR – The bottom portion of the cell container which mates with the cell cover.
KOH – See POTASSIUM HYDROXIDE.
LEAD-ACID – Type of cell or battery that utilizes lead and lead dioxide as the active plate materials in a dilute electrolyte solution of sulfuric acid and water. Nominal cell voltage about 2.0 volts.
LECLANCHE CELL – Often called a carbon-zinc cell, this is a commonly used primary cell having a zinc anode (negative) as the casing, a manganese-dioxide cathode (positive), and using ammonium chloride paste as the electrolyte plus other substances which include a depolarizing agent. A carbon rod serves as a current collector for the cathode.
LIFE – The duration of satisfactory performance, measured as usage in years or as the number of charge/discharge cycles.
LOW-RATE DISCHARGE – Withdrawal of small amounts of current for long periods of time from a cell or battery, usually longer than 1 hour.
MAINTENANCE – The care and procedures necessary to keep a battery in a usable condition, such as reconditioning and water addition to electrolyte of a vented cell.
MANUFACTURING VARIATIONS – Differences in performance characteristics between products of the same design, attributable to process deviations within expected tolerances.
MEMORY EFFECT – A phenomenon in which a nickel-cadmium battery, operated in successive cycles of identical depth of discharge, assumes the capacity customarily demanded of it, temporarily rendering the rest of its capacity inaccessible at a useful voltage level.
MERCURY CELL – A cell utilizing a zinc anode (negative), mercuric oxide (cathode), and an electrolyte solution of potassium-hydroxide and water saturated with zincate. Delivers nominal cell voltage of 1.35 volts.
MIGRATION – Directed movement of an ion of the electrolyte under the influence of an electric field.
NEGATIVE ELECTRODE – See NEGATIVE PLATE.
NEGATIVE PLATE – The plate which has an electrical potential below that of the other plate during normal cell operation.
NICKEL-CADMIUM CELL – A secondary cell utilizing nickel oxide and metallic cadmium as the positive and negative plates in an electrolyte solution of potassium hydroxide. Nominal cell voltage 1.2 to 1.3 volts.
NICKEL ELECTRODE – See POSITIVE PLATE.
NOMINAL CAPACITY – See CAPACITY, RATED.
NOMINAL VOLTAGE – Voltage of a fully charged cell or battery when delivering rated capacity at a specified discharge rate.
OPEN-CIRCUIT VOLTAGE – Voltage of a battery with no load.
OVERCHARGE CURRENT – The charging current supplied to a cell which is fully charged. Continuous, slow charge current rates are often applied to keep nickel-cadmium cells charged.
OVERCHARGING – Continuing the charge after the battery has accepted its maximum amount of charge. The result will be decomposition of water in the electrolyte into hydrogen and oxygen gas.
OXIDATION – The release of electrons by the cell’s active material to the external circuit. During discharge, the active material (e.g., cadmium of a nickel-cadmium cell) at the negative electrode is oxidized.
PERCENT POTASSIUM HYDROXIDE – The percent by weight of potassium hydroxide contained in a given amount of potassium hydroxide solution. May be determined by specific gravity measurement or by titration.
PLAQUE – A porous body of sintered metal used as a current collector and holder of electrode active materials.
PLATE – A grid or framework that gives mechanical support to the active materials of a cell. The combination is termed an electrode.
PLATE PACK – The stack of positive and negative plates into which the separator has been interleaved.
PLATE PACK ASSEMBLY – The plate pack onto which terminals have been attached. Also known as the plate pack and terminal assembly.
POLARITY – The electrical term used to denote the voltage relationship to a reference potential.
POSITIVE ELECTRODE – See POSITIVE PLATE.
POSITIVE PLATE – The plate which has an electrical potential higher than that of the other plate during normal cell operation.
POTASSIUM HYDROXIDE – A chemical compound which, when mixed with pure water in the correct proportions, is
the electrolyte solution used in nickel-cadmium cells.
POWER EFFICIENCY – The proportion, expressed in percent, of energy recovered from a storage system; i.e., output power divided by input power.
PRIMARY CELL – A cell designed to be used only once, then discarded. It is incapable of being recharged (returned to its original charged state by the application of current).
PRIMARY SYSTEM – Cell or battery that cannot be recharged efficiently or safely after any amount of discharge.
PSIA – Pounds per square inch measured relative to empty space, i.e., absolute pressure.
PSIG – Pounds per square inch measured as the difference in pressure between two spaces; i.e., relative pressure.
RATE – Amount of current, sometimes expressed as a fraction or decimal of the current necessary to discharge the cell in 1 hour, i.e., a fraction of the C. rate.
RATING – See CAPACITY, RATED CAPACITY.
RECHARGEABLE PRIMARY CELL OR BATTERY – A cell or battery which is ordinarily used in .one-shot service but which is capable of limited number of charge-discharge cycles (frequently 5 to 10). Term almost exclusively applied to silver-zinc missile batteries.
RECHARGEABLE SECONDARY CELL OR BATTERY – A cell or battery which can be recharged many times after being discharged without appreciable depreciation of capacity.
RECOMBINATION – The chemical reaction of gases at the electrodes to form a nongaseous product.
RECONDITIONING – The deep discharge, constant-current charge process used to correct any cell imbalance acquired during battery usage.
RECYCLABILITY – The capability of a battery system to be charged and discharged.
REDUCTION – The gain of electrons; in a cell, refers to the inward flow of electrons to the active material. During discharge, nickel-hydroxide at the positive plate of a nickel-cadmium cell is reduced to a lower oxidation state.
RESEALABLE – In a cell, pertains to a safety vent which is capable of closing after each pressure release, in contrast to the non-resealable ‘one-shot’ vent.
RESERVE PRIMARY CELLS – A primary cell that can be stored in a dry state for an extended period of time and then activated with electrolyte when needed.
REVERSIBLE REACTION – A chemical change which takes place in either direction, as in the reversible reaction for charging or discharging a secondary battery.
SEALED CELLS – Cells that are free from routine maintenance and can be operated without regard to position. Many sealed-cell models are designed with a high-pressure vent.
SECONDARY BATTERY – A system which is capable of repeated use by employing chemical reactions that are reversible, i.e., the discharged energy may be restored by supplying electrical current to recharge the cell.
SECONDARY SYSTEM – Cell or battery that can be recharged after being discharged.
SELF-DISCHARGE – The decrease in the state of charge of a cell or a battery over a period of time, due to internal electrochemical losses.
SEPARATOR – An insulating sheet or other device employed in a storage battery to prevent metallic contact between plates of opposite polarity within a cell.
SHELF LIFE – For a dry cell or battery, the period of time (measured from date of manufacture) at a specified storage temperature after which the cell or battery retains a specified percentage of its original energy content. (Also refer to WET SHELF LIFE.)
SHORTING CLIP – A metal spring designed to be placed between terminals to short the cell to zero volts.
SILVER-CADMIUM CELL – A cell utilizing silver and cadmium as the active materials of the cell plates in a dilute electrolyte solution of potassium hydroxide and water. Capable of high discharge rates at virtually constant terminal potential.
SILVER-OXIDE PRIMARY CELL – A cell using a silver-oxide cathode (positive) and zinc anode (negative) in a dilute solution of potassium hydroxide and water. This cell has a flat discharge characteristic, high energy capacity, and low cycle life. Nominal cell voltage is 1.5 volts.
SILVER-ZINC CELL – Same as SILVER-OXIDE CELL.
SINTERED PLATE – A cell plate prepared by placing active powdered material in a retaining grid or expanded metal and increasing temperature until the point contacts of the powder particles fuse together, making a highly porous, absorbent active material structure. Provides a much larger equivalent surface area and allows higher discharge rates with improved efficiency compared to other methods of impregnation with active materials. Usually applies to nickel-cadmium or silver-zinc batteries.
SOAK TIME – The time required for the electrolyte to be absorbed sufficiently into the active materials of the cells after activation to allow the battery or cell to be placed in service.
SPECIFIC ENERGY – The energy storage ability of a battery on a weight basis, usually expressed in watt-hours per pound (or kilogram); sometimes given on a volume basis in watt-hours per cubic foot (or liter).
SPECIFIC GRAVITY – The weight of a substance compared with the weight of the same volume of water at the same temperature
STARVED CELL – A cell containing little or no free fluid electrolyte solution; this enables gases to reach electrode surfaces readily and permits relatively high rates of gas recombination. See SEALED CELL.
STATE-OF-CHARGE – The available ampere-hours in a battery at any given time.
TAB – A battery terminal, often containing a hole for wire connection.
TEMPERATURE, AMBIENT – The average temperature of the battery’s surroundings.
TEMPERATURE, CELL – The average temperature of the battery’s components.
TERMINAL – An electrical conductor used in a cell to make external electrical connection to the cell plates.
THERMAL RUNAWAY – A chain reaction in which the heat generated within the battery by the overcharge current lowers the battery’s internal resistance. This, in turn, progressively increases the charging rate and the heat being generated. In the final stages, enough excess heat may be generated to destroy the battery.
TITRATION – A chemical method used to measure the quantity of a specific compound in a solution.
TRICKLE CHARGING – Method of charging in which a secondary cell or battery is either continuously or intermittently connected to a constant current charging source that maintains the cell in a fully charged condition.
VENT – A normally-sealed mechanism which allows the controlled escape of gases from within a cell.
VENT CAP – The plug on top of a cell that regulates the maximum internal pressure and prevents electrolyte spillage. It can be removed to allow for electrolyte level adjustment.
VENTED CELL – A heavy-duty cell design in which the vent operates at low pressures during the normal duty cycle to expel gases generated in overcharge. A vented cell plate pack contains flat plates, separated by a gas barrier and woven nylon separator, completely immersed in electrolyte. Often called “flooded” cell.
VOLTAGE LIMIT – In a charge-controlled battery, limit beyond which battery potential is not permitted to rise during or after the charging process.
WET – Term used to denote that the electrolyte in the cell or battery is liquid and free-flowing.
WET CHARGED STAND – Period of time that a wet secondary cell or battery can stand in charged condition without losing a specified small percentage of its capacity, when stored under specified conditions.
WET SHELF LIFE – Period of time that a wet secondary cell or battery can stand in a discharged condition before deteriorating to a point where it cannot be recharged to a normal state.
WOUND – The interior cell construction in which plates are coiled into a spiral.
