Battery Glossary

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A physical or chemical process in which something (atoms, molecules or ions) takes in another substance.


Alkaline Battery

A disposable, rechargeable battery with a high energy density that has storage longevity. Mostly used in consumer electronics such as remote controls, flashlights, etc.



Elements in a metallic matrix that make up a partial or complete solid solution.



Rotating machines or generators that use a form of electrical alternating current. Widely used in automotive or other combustion engines.


Ambient Humidity

The average humidity of the surroundings.


Ambient Temperature

The average temperature of the surroundings.



A unit of electric charge measured as 3600 amp-seconds of current of one amp for one hour.



The electrode by which current enters a battery. While discharging the battery, the negative electrode is the anode. When charging the battery, the positive electrode is the anode.


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A combination of electrochemical cells working together to produce voltage or electric current.


Battery Charger

A device forcing electric current into an alternate cell.



A cylinder shaped reel around which insulated wire is wound.


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Measured in amp-hours, capacity is a battery's ability to store an electrical charge.



A dry cell less expensive battery that is commonly packaged by manufacturers when selling products that include batteries. Labeled as ""General Purpose"" batteries, they are commonly used in clocks or remote controls where the power drain is typically lower.



 The opposite of the anode. While discharging the battery, the positive electrode is the cathode. When charging the battery, the negative electrode is the cathode.



The part of a battery used to extract electricity from a chemical reaction.


Closed-circuit Voltage (CCV)

The measurement of a battery in a discharging state.


Constant Current

A process by where the current drawn during the discharge of a battery remains the same.


Constant Power

A process by where the current during the discharge of a battery increases as the battery voltage decreases.


Constant Resistance

A process by where the resistance of the equipment load remains unchanging throughout discharge.


Continuous Test

A test in which a battery is discharged to a prescribed end point voltage without interruption.



A derived unit of electrical charge (SI). One coulomb = the amount of electric charge transferred in one second by a steady current of one amp.


Current Collector

Commonly used for trolley buses or trams, current collectors lead electrical current from lines or rails to the electrical equipment they power.


Current Density

The current per unit active area of the surface of an electrode.


Current Drain

The current withdrawn from a battery during discharge.


Cutoff Voltage

The low limit voltage at which a battery discharge is considered complete.


Cycle Life

The number of cycles (a sequence where a battery is discharged and recharged) under specified conditions that are available from a secondary battery.


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Depth of Discharge

The ratio of the quantity of electricity (usually in ampere-hours) removed from a battery to its rated capacity.



The opposite of absorption. A physical or chemical process in which something (atoms, molecules or ions) releases another substance.


Direct Current

Direct current or DC is a one directional flow of electrical charge.



The withdrawal of electrical energy into a load.


Discharge Rate

The amps at which electrical current is taken from a battery.


Dry Cell Battery

A cell with immobilized electrolyte. A battery with only enough moisture in it to allow current to flow.


Duty Cycle

The period of time in which the battery is in use.


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Discharge or charge power, in watts, expressed as a multiple of the rated capacity of a cell or battery that is expressed in watt-hours. For example, the E/10 rate for a cell or battery rated at 17.3 watt-hours is 1.73 watts.


Electric Current

The movement of electric flow along a conductor.



An electrochemical cell referred to as either an anode or cathode.



A conducting medium in which the flow of current is associated with the movement of ions.



Negatively charged particles that orbit the nucleus of an atom.


End Voltage Cutoff

The prescribed voltage at which the discharge (or charge, if end-of-charge voltage) of a battery may be considered complete.



Usually expressed in watt-hours, energy is the output of a battery or cell.


Energy Density

The ratio of the energy available from a battery to its volume (Wh/L) or weight (Wh/kg).


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Forced Discharge

Discharging a cell in a battery, by the other cells or an external power source, below zero volts into voltage reversal.



In an electrical system, a fuse is used to protect against excessive current.


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In a lead-acid battery, excessive charging will cause the emission of hydrogen and oxygen as water of the electrolyte is broken down by electrolysis. This is the process of gassing.



A machine that converts one form of energy into another.



A common return path for electric current. A connection between an electric circuit and the earth.


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Hazardous Waste

Any chemical or industrial by-product that is destructive to the environment.


Hertz (Hz)

The standard unit of frequency. The most common uses are to describe radio and audio frequencies.



A device used to measure the specific gravity of a liquid.


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Impedance Intermittent Test

A test during which a battery is subjected to alternate periods of discharge and rest according to a specified discharge regime.


Internal Resistance (IR)

The opposition exhibited by a circuit element to the flow of direct current (D.C.).


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Limiting Current

The maximum current where the battery will perform to its fullest potential under a continuous drain.


Lead Acid Battery

Invented in 1859, it is the oldest type of rechargeable battery. This battery has lead electrodes and sulphuric acid as the electrolyte. It's main application today is in the automobile industry.



Lithium, or Li, is a soft silver-white metal and is the lightest of all metals.


Lithium Ion (Li Ion) Battery

A very light, rechargeable battery commonly used in notebook computers, cell phones and camcorders. As one of the newer batteries out today, this battery can give 40% more capacity than a comparable sized NiCd battery.


Load Current

The discharge current provided by a battery.


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Manganese Dioxide

A black crystalline compound, MnO2, that is used as the cathode in standard and alkaline disposable batteries.


Memory Effect

Found in NiCd rechargeable batteries, it is the phenomenon that causes a battery to hold less of a charge than it's capable of. These batteries gradually lose their maximum capacity if they are repeatedly recharged after only being partially discharged.


Midpoint Voltage

The voltage of a battery midway in the discharge between the start of the discharge and the end voltage.



A unit of electric current. It's name is often shortened to amp and it is measured as one coulomb per second.


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A terminal or electrode which has an excess of electrons.


Nickel Cadmium Battery

NiCd is a type of rechargeable battery that uses nickel oxide hydroxide and cadmium as electrodes. Widely used in applications such as power tools, they have a high discharge rate but have low capacity compared to other rechargeable batteries.


Nickel Metal Hydride (NiMh) Battery

This battery uses a hydrogen absorbing alloy for the negative electrode instead of cadmium. They are interchangeable with most NiCd batteries, but NiMh batteries have a greater capacity and they are more environmentally friendly.


Nominal Voltage

The voltage given by a manufacturer as the recommended operating voltage for their specific product.


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A measure of resistance that causes one volt to produce a current of one ampere.


Open-Circuit Voltage

The supply voltage with the load disconnected or broken.


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Having component parts connected in parallel. i.e. a parallel circuit.



In electricity, the condition of being positive or negative.



Increasing the resistance of the cell, polarization is the deposit of gases on the electrodes of a cell.



A terminal or electrode which has a shortage of electrons.


Primary Battery

A primary battery is a disposable battery as opposed to a rechargeable battery.


Pulse Current

A periodic current drain of higher than normal drain rates.


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Rapid Charge

A charge time that is between slow charge and fast charge (typically 3 to 6 hours for a NiCd).


Rated Capacity

Usually specified by the battery manufacturer, it is the number of amp-hours a battery can supply under certain conditions.


Rechargeable Battery

As opposed to a disposable battery, a rechargeable battery can be recharged many times and used again, although the initial cost of a rechargeable battery may be sizable.



One or more deep discharge cycles below 1.0 volt/cell at a very low, controlled current. Recondition helps to revert large crystals to small desirable sized, often restoring the battery to it's fullest capacity.



Often measured in ohms, resistance is the measure to which an object opposes an electric current running through it.



The changing of the normal polarity of a battery.


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Safety Vent

A venting mechanism designed into a cell which activates under specific conditions of abuse to relieve internal pressure.


Secondary Battery

A battery that can be recharged and reused many times.



The capacity of a battery that is lost when it is not used or simply sitting on the shelf.


Service Life

The expected life time of a product.


Shelf Life

The duration of storage under specified conditions at the end of which the battery still retains the ability to give a specified performance.


Short Circuit

Often times called a short, it is a current that is allowed to travel on a different path than where it was originally intended. This can cause circuit damage, overheating or fire.


Slow Charge

A semi constant current that typically charges overnight 14-16 hours.


Smart Battery

A battery that offers communication between itself and the user to let you know when it's in need of charging.


Specific Energy

The energy per unit of mass.


Specific Gravity

The weight of the sulfuric acid electrolyte in a battery compared to water.



The use of batteries in which they are charged by an application to be ready for use if the primary power to the application fails. Also called float or backup.


State of Charge

The capacity remaining in a battery.



The process where a lead-acid battery loses its charge after it's been kept in a discharged state for too long.


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A device at the end of a cell or wire for joining electrical circuits together.



A resistor whose resistance varies with temperature.



A temperature sensitive switch.


Top-Up Charge

A low rate charge following the main charge, designed to ensure maximum capacity.


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The unit of measure of electrical potential. For short, often called a volt.


Voltage Depression

When the peak voltage of the battery drops more quickly than normal as it is being discharged or used.


Voltage Regulator

A device designed to automatically regulate and maintain a constant voltage level.


Volumetric Energy Density

The ratio of the energy output of a cell or battery to its volume (Wh/L).


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A measurement of energy. One watt = one joule of energy per second.


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Zinc/Air Battery

A non-rechargeable battery powered by oxidizing zinc and oxygen. Widely used in hearing aids and film cameras.


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