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Aircraft Battery Glossary

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.
Active Material -electrode material which produces electricity during its chemical conversion.
Ampere -Unit of electrical current. (Volts/Watts=Amps or V/W=A)
Ampere Hour (Ah) -The capacity of a storage battery is measured in ampere-hours. One ampere hour is defined as a current flow of one ampere for a period of one hour. Five ampere-hours means a current flow of one ampere for five hours, a current flow of 2 1/2 ampere for 2 hours, or any multiple of current and time that will result in five. This relationship can be expressed as follows: Capacity (In ampere hours)= I*T. Where I is the current (in amperes) and T is the time (in hours). The capacity of a storage battery is usually based on a given discharge rate, since the capacity will vary with the rate of discharge. The capacity of an aircraft battery is usually based on a one hour discharge rate. A 17 ampere hour battery will supply a current of approximately 17 amperes for a period of one hour. A 34 ampere battery will deliver twice that amount of current over the same period of time. If a very heavy load is applied to the battery, it may become discharged in a few minutes.
Battery -A combination of two or more chemical cells electronically connected together to produce electric energy.(Common usage permits this designation to be applied also to a single cell used independently.)
Boost Charge -A charge applied to a battery which is already near a state of full charge, usually of short duration.
C1 Rate -Discharge or current rate in amperes; numerically equal to rated capacity of a cell in ampere-hours.
Capacity -The quantity of electricity delivered by a battery under specified conditions, usually expressed in ampere-hours.
Capacity Reconditioning -See Reconditioning.
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, 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 -See Nominal Capacity.
Capacity, Residual -Capacity remaining at 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.
Case -The battery box or enclosure which contains the cells and associated connectors and hardware.
CB Series -as pertaining to Concorde Battery Corporation
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 Reversal -Reversing of polarity within a cell in a multi-cell battery due to over discharge.
Charge -The conversion of electrical energy from an external source, into chemical energy within a cell or battery.
Charge Rate -The rate at which current is applied to a secondary cell or battery to restore its capacity.
Charge Retention -The tendency of a charged cell or battery to resist self-discharge.
Charge, State of -The condition of a storage cell or battery in terms of the remaining capacity.
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.
Concavo-Concave -RG batteries have one-way cell vent valves designed to relieve excess positive internal pressure. Occasionally, when the atmospheric pressure is greater than the internal pressure of the battery, caused by rapid decrease in altitude, the battery case may become temporarily concave.
Connector -An electrically conducive bar or wire which joins individual cells together in a battery.
Constant Current (CI) Charge -Charging technique where the output current of the charge source is held constant. Warning! This procedure may damage the battery if performed on a repetitive basis.
Constant Potential (CP) Charge -Charging technique where the output voltage of the charge source is held constant and the current is limited only by the resistance of the battery.
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 reduced 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.
Counter EMF -Voltage or a cell or battery opposing the voltage of the charging source.
Current -The rate of flow of electricity. The movement of electrons along a conductor. It is comparable to the flow of a stream of water. The unit of measurement is an ampere.
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.
Cut Off Voltage -Battery voltage reached at the termination of a discharge. Also known as end point voltage or EPV.
Cycle -On 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.
Deep Discharge -Withdrawal of 50% or more of the rated capacity of a cell or battery.
Deionized Water -Water which has been freed of ions by treatment with ion exchange resins.
Depth Of Discharge -The portion of the nominal capacity from a cell or battery taken out during each discharge cycle, expressed in percent. Shallow depth of discharge is considered as 10% or less, deep depth of discharge is considered 50% or more.
Discharge -The conversion of the chemical energy of a cell or battery into electrical energy and withdrawal of the electrical energy into a load.
Discharge rate -The rate of current flow from a cell or battery.
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 of battery has been partially discharged at a higher current rate.
Dry Charge -Process by which the electrodes are formed and assembled in a charged state. The cell or battery is activated when the electrolyte is added.
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 accord to specifications.
Duty Cycle -The conditions and usage to which a battery is subjected during operation, consisting of charge, overcharge, and discharge.
Electrode -Conducting body in which active materials are placed and through which current enters or leaves cell.
Electrolyte -In a lead-acid battery, the electrolyte is sulfuric acid diluted with water. It is a conductor and is also a supplier of hydrogen and sulfate ions for the reaction.
Electromotive Force (EMF) -Potential causing electricity to flow in a closed circuit.
Electron -That part of an atom having a negative charge.
End Of Discharge Voltage -The voltage of the battery at the termination of a discharge but before the discharge is stopped. See End Point Voltage (EPV).
End Of Life -The stage at which the battery or cell meet specific failure criteria.
End Point Voltage -Cell or battery voltage at which point the rated discharge capacity had 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 or voltage end point.
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 with 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/
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.
External Power -A device that is used to supply electrical power via a cable and plug to the airframe external power receptacle. External power is used to prevent the aircraft batteries from being discharged during maintenance or often used for electrical power during engine starting. Some airframe external power electrical systems are designed to bypass the battery buss to prevent the batteries from being overcharged. To prevent the batteries from being overcharged, we recommend that the batteries be disconnected if the airframe external power electrical system design does not bypass the battery buss when external power is on in excess of four hours. External power should not be set higher than 2.38 volts per cell, 14.2 for 12 volt batteries and 28.5 DCV for 24 volt batteries.
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 charge -A method of maintaining a cell or battery in a charged condition by continuous, long-term, constant voltage charging at level sufficient to balance self-discharge.
Flooded cell -A cell design which incorporates an excess amount of electrolyte, also see Vented Cell.
Gassing -The evolution of gas from one or more of the electrodes in a cell. Gassing commonly results from local action (self discharge) or from the electrolysis of water in the electrolyte during charging.
Ground -In aircraft use, the result of attaching one battery cable to the body or airframe which is used as a path for completing a circuit in lieu of a direct wire from a component.
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.
Hydrometer -A float type instrument used to determine the state-of-charge of a battery by measuring the specific gravity of the electrolyte (i.e. the amount of sulfuric acid in the electrolyte).
Internal Impedance -The opposition to the flow of an alternating current at a particular frequency in a cell or battery at a specified state-of-charge and temperature.
Internal Resistance -The opposition or resistance to the flow of a direct electric current within a cell or battery; the sum of the ionic and electronic resistance of the cell components. Its value may vary with the current, state-of-charge, temperature, and age. With an extremely heavy load, such as an engine starter, the cell voltage may drop to approximately 1.6. This voltage drop is due to the internal resistance of the cell. A cell that is partly discharged has a higher internal resistance than a fully charged cell, hence it will have a greater voltage drop under the same load. This internal resistance is due to the accumulation of lead sulfate on the plates. The lead sulfate reduces the amount of active material exposed to the electrolyte, hence it deters the chemical action and interferes with the current flow.
Ion -Part of a molecule or group of atoms, positively or negatively charged, which transports electricity through the electrolyte.
Joules -Unit of energy, equal to a watt/second (newton/meter).
Lead Acid -Terms used in conjunction with a cell or battery that utilizes lead and lead peroxide as the active plate materials in a diluted electrolyte solution of sulfuric acid and water. Nominal cell voltage about 2.1 volts.
Lead Dioxide -A higher oxide of lead present in charged positive plates and frequently referred to as lead peroxide.
Lead Sulfate -A lead salt formed by the action of sulfuric acid on lead oxide during paste mixing and formation. It is also formed electrochemically when a battery is discharged.
Life -The duration of satisfactory performance, measured as usage in years or as the number of charge/discharge cycles.
Lithium Ion Aircraft Battery -Main aircraft battery built with safest chemistry in Lithium ion batteries, a cathode material of lithium iron phosphate which inhibits oxygen generation. Lithium ion aircraft batteries must be integrated into the control software and electronics of the aircraft system with redundant built in safety features.
Load Tester -An instrument which measures the battery voltage with an electrical load on the battery to determine its overall condition and its ability to perform under engine starting conditions or essential power requirements.
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 usable condition, such as reconditioning and water addition to electrolyte of a vented cell.
Manifold -A portion of the battery case enclosing the vent caps or vent valves. Sometimes with ports that can be connected overboard for ventilation.
Manufacturing Variations -Differences in performance characteristics between products of the same design, attributable to process deviations within expected tolerances.
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 call operation.
Nominal Capacity -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.
Nominal Voltage -Voltage of a fully charged cell or battery when delivering rated capacity at a specified discharge rate.
Open Circuit Voltage -The voltage of a battery when it is not delivering or receiving power.
Overcharge -The forcing of current through a cell after all the active material has been converted to the charged state. In other words, charging continued after 100% state-of-charge is achieved. The result will be the decomposition of water in the electrolyte into hydrogen and oxygen gas.
Oxygen recombination -The process by which oxygen generated at the positive plate during charge reacts with the pure lead material of the negative plate and in the presence of sulfuric acid and reforms water.
Parallel connection -A circuit in which battery poles of like polarity are connected to a common conductor.
Plate -A grid or framework that gives mechanical support to the active materials of a cell. The combination is termed an electrode.
Platinum Series -As pertaining to Concorde Battery Corporation
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.
Power -Rate at which energy is released or consumed (expressed in watts).
Power Efficiency -The proportion, expressed in percent, of energy recovered from a storage system, i.e: output power divided by input power.
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.
Rated Capacity -The number of Ahs a battery can deliver under specific conditions (rate of discharge, end voltage, temperature).
Rating -See Capacity, Rated Capacity.
Rechargeable Secondary
Cell or Battery
A cell or battery which can be recharged many times after being discharged without appreciable depreciation of capacity.
Recombination -State in which the hydrogen and oxygen gases normally formed within the battery cell during charging are recombined to form water.
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.
Resealable -In a cell, pertains to a safety vent valve which is capable of closing after each pressure release, in contrast to the non resealable vent cap.
Reversible Reaction -A chemical change which takes place in either direction, as in the reversible reaction for charging or discharging a secondary battery.
S or SS -as pertaining to Concorde Battery Corporation
Sealed Cells -Cells that are free from routine maintenance and can be operated without regard to position.
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.
Self Discharge -The decrease in the state-of-charge of a cell or a battery, over a period of time, due to the internal electro-chemical 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).
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 (S.G.) -The weight of the electrolyte is compared to the weight of an equal volume of pure water, used to measure the strength or percentage of sulfuric acid in the electrolyte.
Starved Cell -A cell containing little or no free fluid electrolyte solution; this enables gases to reach electrode surfaces readily, and permits relative high rates of recombination.
State Of Charge (SOC) -The available ampere-hours in a battery at any given time. State-of-charge is determined by the amount of sulfuric acid remaining in the electrolyte (S.G.) at the time of testing or by the stabilized open-circuit voltage.
Sulfation -In its common usage, the term refers to the formation of lead sulfate of such physical properties that it is extremely difficult, if not impossible, to reconvert it to active material.
Swelling -RG Battery cases swell or bulge when the cell vent valves maintain an internal pressure that is greater than the outer (atmospheric) pressure.
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.
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.
TSO - Technical Standard Order -FAA approval authorizing a manufacturer to produce a product or part to a certain minimum standard. In Concorde's case this is TSO C173 - aircraft batteries.
Vent Cap -The plug on top of a cell. It can be removed to allow for electrolyte level adjustments.
Vent Valve -A normally sealed mechanism which allows the controlled escape of gases from within a cell.
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 a 'flooded cell.'
Venting -A release of gas either controlled (through a vent) or accidental.
Volt -Unit of electromotive force, voltage or potential. The volt is the voltage between two points of a conductor carrying a constant current of one ampere, when the power dissipated between these points is one watt.
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.
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