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Battery Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z  

A ………………………………………………………………………………………………………………………….

Alkaline: A primary battery (non-rechargeable) often used in electronics applications requiring heavy currents for long periods of time (i.e.: CD players, radios, etc.). Alkaline batteries can deliver 50-100% more total energy than conventional Carbon/Zinc batteries of the same size, hence their popularity in consumer applications.
Ampere-Hour: It is an unit to measure battery capacity of at different current for different durations.
Ampere-Hour Capacity: It measures the electricity stored in a battery.
Anode: The electrode in an electrochemical cell where oxidation takes place. During discharge, the negative electrode of the cell is the anode. During charge, the positive electrode is the anode. In a primary or secondary cell, the metal electrode that gives up electrons to the load circuit and dissolves into the electrolyte.
Available Battery Capacity: The available capacity from a battery at working conditions. It depends on several factors such as usage history, discharge rate, using condition, and end-point voltage.
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Battery: A energy storage device that can turn chemical energy into electrical energy.
Battery Capacity: The total electric output of a battery can deliver. It is usually expressed in ampere-hours or watt-hours. You can convert the ampere-hours capacity into watt-hours by multiplying the former by battery voltage.
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C …………………………………………………………………………………………………………………………..

C-Rate (also see Hourly Rate): Discharge or charge current, in amperes, expressed in multiples of the rated capacity. For example, C/10 discharge current for a battery rated at 1.5 Ah is: 1.5 AH/I 0 = 150 mA (A cell's capacity is not the same at all discharge rates and usually increases with decreasing rate.)
Capacity: The total number of ampere-hours or watt-hours that can be withdrawn from a fully charged cell or battery under specified conditions of discharge.
Capacity Offset: A correction factor applied to the rating of a battery if discharged under different C-rates from the one rated.
Capacity Retention (or Charge Retention): The fraction of the fall capacity available from a battery under specified conditions of discharge after it has been stored for a period of time
Carbon/Zinc: A primary battery (non-rechargeable) commonly used in low drain consumer applications (i.e.: clocks, calculators, garage door openers, etc.). Available in the same sizes as the Alkaline and Manganese Dioxide (“AA”, “AAA”, 9 volt, “C”, “D”) the Carbon/Zinc is one of the most widely used dry primary batteries because of its low cost and reliable performance.
Charge: The process of converting electrical energy into chemical energy.
Charge Rate: The charging current applied to a rechargeable battery. Expressed as a multiple of the rated capacity of the Battery. For example, a C5 charge rate of a 50 Ah cell is expressed as, C5 rate = 50 Ah / 5 h = 10 A.
Cathode: The electrode in an electrochemical cell where reduction takes place. During discharge, the positive electrode of the cell is the cathode. During charge in a rechargeable battery, the negative electrode is the cathode.
Cell: The basic electrochemical unit used to generate or store electrical energy.
Cell Mismatch: Cells within a battery pack that contain different capacity and voltage levels.
Cell Reversal: The stronger cells of a battery (several cells connected in series) impose a voltage of reverse polarity across a weaker cell during a deep discharge.
Charger: A device capable of supplying electrical energy to a battery.
Charge Control: Technique for effectively terminating the charging of a rechargeable battery.
Conditioning: A process that utilizes a series of heavy discharges and recharges on a battery to assure optimum performance.
Constant Current: A battery discharge regime whereby the current drawn during the discharge remains constant.
Constant Power: A battery discharge regime whereby the current during the discharge increases as the battery voltage decreases.
Constant Resistance: A battery discharge regime whereby the resistance of the equipment load remains constant throughout discharge.
Continuous Test: A test in which a battery is discharged to a prescribed end point voltage without interruption.
Coulomb: The amount of electricity transported by a current of one ampere flowing for one second.
Current Collector: An inert structure of high electrical conductivity used to conduct current from or to an electrode during discharge or charge.
Current Density: The current per unit active area of the surface of an electrode.
Current Drain: The current withdrawn from a battery during discharge.
Current Limiting Chargers: A charger that keeps the charge current constant during the charge process but allows the voltage to Fluctuate (typically used on NiCd and NiMH chargers).
Cutoff Voltage: The battery voltage at which the discharge is terminated. The cutoff voltage is specified by the battery manufacturer and is generally a function of discharge rate.
Cycle: A sequence where a charged battery is discharged and recharged.
Cycle Life: The number of cycles under specified conditions that are available from a secondary battery before it fails to meet specified criteria as to performance.
Cylindrical Cell: The positive and negative plates are rolled up and placed into a cylindrical container (as opposed to stacking the plates in a prismatic cell design).
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D …………………………………………………………………………………………………………………………..

Deep Discharge: Withdrawal of all electrical energy to the end-point voltage before the cell or battery is recharged.
Depth of Discharge: The ratio of the quantity of electricity (usually in ampere-hours) removed from a battery to its rated capacity.
Direct Current: Electrical current that flows in one direction only. Batteries produce direct current as the current flows from a negative to a positive source.
Discharge: The conversion of the chemical energy of a battery into electrical energy, and the withdrawal of the electrical energy into a load.
Discharge Rate: The rate, usually expressed in amperes, at which electrical current is taken from the battery.
Drain: The current withdrawn from a battery during discharge.
Dry Cell: A cell with immobilized electrolyte.
Dumb Battery: Straight battery pack without internal circuits enabling communication between the battery and the user.
Duty Cycle: The operating regime of a battery including factors such as charge and discharge rates, depth of discharge, cycle duration, and length of time in the standby mode.
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E …………………………………………………………………………………………………………………………..

E-Rate: 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. (This is similar to the method for calculating C-Rate.)
Electric Current: The movement of electrons along a conductor.
Electrochemical Equivalent: Weight of a substance that is deposited at an electrode when the quantity of electricity which is passed is one coulomb
Electrolyte: The medium which provides the ion transport mechanism between the positive and negative electrodes of a cell.
End-point Voltage: The prescribed voltage at which the discharge (or charge, if end-of-charge voltage) of a battery may be considered complete.
End Voltage Cutoff: same as End Point Voltage.
Energy Density: The ratio of the energy available from a battery to its volume (Wh/L) or weight (Wh/kg).
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F …………………………………………………………………………………………………………………………..

Fast Charge: Typical fast charge time for a NiCd is 1 to 3 hours. The fast-charger detects the state of charge and switches to trickle charge when full-charge is reached.
Final Battery Voltage: Same as Cutoff voltage, it the bottom limit voltage when the battery is completely discharged. It depends on battery types, discharge rate and other use conditions.
Float: 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 standby or backup.
Float Charge: Similar to trickle charge. Compensates for the self-discharge on a SLA battery
Forced Discharge: Discharging a cell in a battery, by the other cells or an external power source, below zero volts into voltage reversal.
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G …………………………………………………………………………………………………………………………..

Gravimetric Energy: The ratio of the energy output of a cell or battery to its weight (Wh/kg). This term is used interchangeably with specific energy.
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H …………………………………………………………………………………………………………………………..

High-rate Discharge: Withdrawal of large currents for short intervals of time, usually at a rate that would completely discharge a cell or battery in less than one hour.
Hourly Rate: A discharge rate, in amperes, of a battery which will deliver the specified hours of service to a given cutoff voltage.
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I …………………………………………………………………………………………………………………………..

Impedance Intermittent Test: Used in terms of the battery's internal resistance a test during which a battery is subjected to alternate periods of discharge and rest according to a specified discharge regime.
Internal Impedance: The opposition exhibited by a circuit element (cell or battery) to the flow of an alternating current (a/c.) of a particular frequency as a result of resistance, induction and capacitance.
Internal Resistance (IR): The opposition exhibited by a circuit element to the flow of direct current (D.C.). In a cell, the internal resistance is the sum of the ionic and electronic resistances of the cell components.
IR Drop: A voltage drop associated with the electrical resistance (R) of a battery or current flow (I). The voltage drop is the product of the current (in amperes) and the resistance (in ohms).
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L …………………………………………………………………………………………………………………………..

Limiting Current: The maximum current drain under which the particular battery will perform adequately under a continuous drain. The rate is based on whatever drain rate reduces the running voltage to 1.1 volts.
Lithium Ion (Li Ion): One of the newer rechargeable battery technologies, Li Ion batteries can deliver 40% more capacity than comparably sized NiCd batteries and are one of the lightest rechargeable batteries available today. Li Ion batteries are the batteries of choice in notebook computers, wireless telephones and many camcorder models. They are also one of the more expensive rechargeable technologies.
Lead Acid: Still the most popular battery used today its main application is for the automobile industry, although it has a growing number of other applications. Its advantages are low cost, high voltage per cell and good capacity life. Disadvantages are poor low temperature characteristics, it is relatively heavy, and it cannot be left in a discharged state for too long without being damaged. Related Batteries: Absorbent Glass Matt (AGM) Gel/Gel Cell Sealed Lead Acid
Lithium: A primary battery (non-rechargeable) that is quickly entering mainstream electronic designs, particularly in consumer, portable equipment and non-volatile memory back up applications where small size, long life and low cost are the primary requirements. Lithium batteries have superior cold temperature performance and a shelf life of 5-10 years.
Lithium Ion (Li Ion): One of the newer rechargeable battery technologies, Li Ion batteries can deliver 40% more capacity than comparably sized NiCd batteries and are one of the lightest rechargeable batteries available today. Li Ion batteries are the batteries of choice in notebook computer, wireless telephones and many camcorder models. They are also one of the more expensive rechargeable technologies.
Load Current: The discharge current provided by a battery, or drawn by a battery powered device.
Low-rate Discharge: Withdrawal of small currents for long periods of time, usually longer than one hour.
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M …………………………………………………………………………………………………………………………..

Manganese Dioxide: A primary battery (non-rechargeable) similar to that of the alkaline battery though not as strong in total energy. Available in the same size as Alkaline and Carbon/Zinc ("AA", "AAA", "C", "D", 9volt) the Manganese Dioxide chemistry is noted for its ability to retain its charge while being stored at high temperatures and operates well at temperatures as low as -40°C with little loss of capacity.
Memory Effect: Typically only seen in Ni-Cd batteries. It refers to the fact if a rechargeable battery is used in successive cycles, but not to the full capacity at each cycle, can lose rest of its capacity at normal voltage level.
Metal Hydride: An inter-metallic compound or alloy in which hydrogen has been absorbed-, also, the negative electrode in a nickel-metal hydride battery.
Midpoint Voltage: The voltage of a battery midway in the discharge between the start of the discharge and the end voltage.
mAh: Refers to battery capacity. A 1/1000th of an amp-hour, e.g.: 1.0Ah = 1000mAh.
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N …………………………………………………………………………………………………………………………..

Nickel Cadmium (NiCd): One of the most proven and historically most widely used rechargeable batteries. Very dependable and "robust" but contain cadmium and have relatively low capacity when compared to other rechargeable systems. Very good high rate discharge capabilities make them very popular in high drain applications such as power tools.
Nickel Metal Hydride (NiMH): Interchangeable with most NiCd batteries, nickel metal hydride (NiMH) batteries generally deliver 10-25% greater capacity than NiCds and are environmentally friendlier than NiCds since they do not contain cadmium. Used in many wireless phone and camcorders.
Nominal Voltage: The characteristic operating voltage or rated voltage of a battery.
Non-aqueous Batteries: Cells that do not contain water, such as those with molten salts or organic electrolytes.
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O …………………………………………………………………………………………………………………………..

Open Circuit: Condition of a battery which is neither on charge nor on discharge (i.e., disconnected from a circuit).
Overcharge: The forcing of current through a cell after all the active material has been converted to the charged state that is, continued charging after reaching 100 percent state-of-charge.
Overdischarge: The process of discharging a cell or battery beyond its cutoff voltage and possibly into voltage reversal.
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P …………………………………………………………………………………………………………………………..

Passivation: The phenomenon by which a metal, although in conditions of thermodynamic instability, remains indefinitely unattacked because of modified or altered surface conditions.
Polarization: The lowering of the potential of a cell or electrode from its equilibrium value caused by the passage of an electric current.
Positive: A terminal or electrode which has a shortage of electrons.
Positive Temperature: A thermally reactive device which becomes highly resistive at a specific Coefficient (PTC) temperature or current.
Primary Battery: A battery which is not intended to be recharged and is discarded when the battery has delivered all of its electrical energy.
Prismatic Cell: The positive and negative plates are stacked rather than rolled as done in a cylindrical cell.
Pulse Current: A periodic current drain of higher than normal drain rates.
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R …………………………………………………………………………………………………………………………..

Rapid Charge: A charge time that is between slow charge and fast charge (typically 3 to 6 hours for a NiCd).
Rated Capacity: The number of ampere-hours a battery can deliver under specific conditions such as rate of discharge, end voltage, temperature. It is usually specified by the battery manufacturer.
Rechargeable battery: A galvanic battery which, after discharge, may be restored to the fully charged state by the passage of an electrical current through the cell in the opposite direction to that of discharge.
Recondition: 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 its full capacity.
Recombination: State in which the gasses normally formed within the battery cell during its operation, are recombined to form water.
Reversal: The changing of the normal polarity of a battery due to over discharging.
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S …………………………………………………………………………………………………………………………..

Safety Vent: A venting mechanism designed into a cell which activates under specific conditions of abuse to relieve internal pressure.
Seal: The structural part of a galvanic cell that restricts the escape of solvent or electrolyte from the cell and limits the ingress of air into the cell (the air may dry out the electrolyte or interfere with the chemical reactions).
Secondary Battery: A battery that can be recharged and reused many times.
Self Discharge: The loss of useful capacity of a battery on storage due to internal chemical action (local action).
Service Life: The period of useful life of a battery before a predetermined end-point voltage is reached.
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.
Slow Charge: Typically an over-night charge lasting abut 14 hours at a charge current of 0.1C. Battery does not require instant removal when fully charged.
Smart Battery: Battery with internal circuit enabling some communication between the battery and the user. Some batteries feature a capacity indicator only, others offer an external bus to interface with the equipment the battery power and the intelligent charger.
Soft Cell: A cell whose voltage rises above its defined boundaries during charging. This voltage rise may be caused by high cell impedance as a result of prolonged battery storage, very cold battery temperature or lack of electrolyte.
Spiral Wound: An electrode structure of high surface area created by winding the electrodes and separator into a spiral-wound jelly-roll configuration.
Standby: 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.
Starting Lighting Ignition (SLI) Battery: A battery designed to start internal combustion engines and to power the electrical systems in automobiles when the engine is not running. SLI batteries can be used in emergency lighting situations.
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T …………………………………………………………………………………………………………………………..

Taper Charge: Changing charge current depends on the status of battery charging. Closer the battery to its full capacity, lower the charging current.
Temperature Cutoff: A protective or safety device (e.g., thermostat, PTC, etc.) which senses temperature in a battery and opens or cuts off the electrical circuit if the specified temperature is exceeded, thus preventing a further rise in temperature due to the charge or discharge of a battery.
Thermal Runaway: A phenomena that generate lots of internal heat, caused by high rate charging, overcharging or other conditions, which can hurt or destroy a battery.
Thermistor: A temperature sensitive resistor usually made from specially processed oxides that are used to sense end of charge temperature rises and terminates high rate charging.
Thermostat: A temperature sensitive switch.
Top Up Charge: A low rate charge following the main charge, designed to ensure maximum capacity.
Trickle Charge: A charge at a low rate, balancing losses through local action and/or periodic discharge, to maintain a cell or battery in a fully charged condition.
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V …………………………………………………………………………………………………………………………..

Vent: A sealed mechanism that allows the escape of gases produced during charging and discharging to escape the battery.
Voltage: A unit of measuring electrical pressure, all batteries is rated in volts DC (Direct Current).
Voltage Depression: An abnormal drop in voltage below expected values during the discharge of a battery.
Voltage Delay: Time delay for a battery to deliver the required operating voltage after it is placed under load.
Voltage-Keyed: A system that incorporates a mechanical identifier on batteries and devices to ensure only batteries of the correct voltage are connected to the device.
Voltage Regulator: A device that regulates the output of a generator or alternator by controlling the current and voltage.
Voltage Reversal: The changing of the normal polarity of a battery due to over discharging.
Volumetric Energy Density: The ratio of the energy output of a cell or battery to its volume (Wh/L).
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W …………………………………………………………………………………………………………………………..

Wall-less Design: A battery design where the structural support for the cells is formed by an open plastic framework.
Watt Hours: A common measurement of energy produced in a given amount of time, arrived at by multiplying the voltage by the amp hours.
Wet Cell: A cell, the electrolyte of which is in liquid form and free to flow and move.
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Z …………………………………………………………………………………………………………………………..

Zinc/Air: A primary battery (non-rechargeable) that was commonly used for applications such as watches and hearing aids. In relation to their physical size, Zinc/Air batteries store more energy per unit of weight (in terms of 220 Wh/kg) than any other primary type.
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