GLOSSARY

Analogue/Digital Converter. A device which converts continuously varying analogue signals into a binary coded digital form.

The electrolyte in a battery is absorbed in an Absorbent Glass Mat between the plates to ensure that there is no free liquid electrolyte to spill or leak from the cell. The battery using this technology is typically referred to as an AGM battery.

A blotter-type separator used between the plates in an AGM battery. The absorbent glass mat separator absorbs the entire free liquid electrolyte, thus immobilizing the electrolyte.

An electric current that reverses direction continuously at regular intervals, most often at a frequency of 50 or 60 Hz. AC appears as a sinusoidal trace on an oscilloscope screen.

An electrical circuit which generates a sine-wave output (regulated and without breaks) using the DC current supplied by the rectifier-charger or the battery. The primary elements of the inverter are the DC/AC converter, a regulation system and an output filter.

A proton donor. A compound containing hydrogen which dissociates in aqueous solution producing positively charged hydrogen ions (H+). An acidic solution has a pH less than 7.0.

The chemically reactive materials in an energy cell which react with each other converting from one chemical composition to another while generating electrical energy or accepting electric current from an external circuit.

Permanent loss of capacity with frequent use or the passage of time due to unwanted irreversible chemical reactions in the cell.

Underwriters' Laboratory (UL), Canadian Standards Association (CSA) and TUV Rheinland Group are safety agencies that test specifications such as component spacing, HI-pot insulation, leakage currents, circuit board flammability and temperature ratings.

A lead acid battery using a glass mat to promote recombination of the gases produced by the charging process.

A compound which dissolves in water producing negatively charged hydroxide ions. Alkaline solutions are strongly basic and neutralize acids forming a salt and water.

A battery which uses an aqueous alkaline solution for its electrolyte.

Two or more forms of the same element in the same physical state (solid, liquid, or gas) that differ from each other in their physical, and sometimes chemical properties. The term allotropy applies to elements only, not compounds. The more general term, used for any crystalline material, is polymorphism. See also isotope.

The average temperature surrounding the battery, typically air.

Without definite shape or structure, without crystalline structure.

The unit of current flow equal to one coulomb per second.

The unit of measure used for comparing the capacity or energy content of a battery with the same output voltage. For automotive (Lead Acid) batteries the SAE defines the Ampere hour capacity as the current delivered for a period of 20 hours until the cell voltage drops to 1.75 V.

Strictly - One Ampere hour is the charge transferred by one amp flowing for one hour. 1Ah = 3600 Coulombs.

A battery in which the electrolyte is stored in a separate chamber from the cell electrodes until the battery is needed.

An electronic circuit in which an electrical value (usually voltage or current, but sometimes frequency, phase) represents something in the physical world. The magnitude of the electrical value varies with the intensity of an external physical quantity.

Also - An electrical circuit which provides a continuous quantitative output (as opposed to a digital output which may be a series of pulses or numbers) in response to its input.

A room whose walls do not reflect either electromagnetic or acoustic waves.

Particles in the electrolyte of a galvanic cell carrying a negative charge and moving toward the anode during operation of the cell. See also cation

Showing differences of property or of effect in different directions.

The electrode in an electrochemical cell where oxidation takes place, releasing electrons. During discharge the negative electrode of the cell is the anode. During charge the situation reverses and the positive electrode of the cell is the anode.

The American National Standards Institute publish standards for batteries jointly with NEMA. (See below)

Chemical components in liquid or gel form.

The relationship between the rate at which a chemical reaction proceeds and its temperature. In general terms, heat speeds up the chemical action.

A battery composed of two or more cells.

The number of nucleons (protons and neutrons) in the atomic nucleus.

Specific to individual elements - represents the number of protons in the atomic nucleus. The same as the number of electrons.

Similar to ESCA but does not provide information on the chemical state (oxidation etc.) of the elements.

Verification that an item is from an approved source and/or that it is able to meet its declared specification.

The number of atoms in 12grams of Carbon-12 (definition) = 6.022 x 1023. By extension, the number of particles in 1 mole of a substance.

A proton acceptor. A compound containing hydrogen which dissociates in aqueous solution producing negatively charged hydroxide (OH-) or other ions. Alkalis are bases and a basic solution has a pH greater than 7.0

Two or more electrochemical energy cells connected together to provide electrical energy.

A power supply system in which, if the AC line fails, a battery will provide input energy to keep the DC outputs from failing.

Electronic circuits designed to monitor the battery and keep it within its specified operating conditions and to protect it from abuse during both charging and discharging.

Sometimes confused with BMS (above) of which it is an essential part, these circuits monitor the key operating parameters (current, voltage, temperature, SOC, etc.) of the battery and provide information to the user.

A cylindrical cell design utilizing an internal cylindrical electrode and an external electrode arranged as a sleeve inside the cell container.

To do something seemingly impossible using only the available resources. In the context of DC battery power circuits it means generating a DC voltage higher than the battery voltage.

A unit of heat energy defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. One Btu is equal to about 252 calories, or 778 foot pounds, or 1.055 kilojoules or 0.293 watt hours.

A switching regulator which incorporates a step down DC-DC converter. A transformerless design in which the lower output voltage is achieved by chopping the input voltage with a series connected switch (transistor) which applies pulses to an averaging inductor and capacitor.

Used by cell designers to predict the current which will flow in a battery. It is the sum of the anodic and cathodic contributions and is directly proportional to the surface area of the electrodes, increasing exponentially with temperature.

Miniature cylindrical cell with a characteristic disc shape.

The preferred programming language for embedded software used in many battery management applications. Robust, fast and powerful, it allows low level access to information and commands while still retaining the portability and syntax of a high level language.

C is a value which expresses the rated current capacity of a cell or battery. A cell discharging at the C rate will deliver its nominal rated capacity for 1 hour. Charging and discharging currents are generally expressed as multiples of C. The time to discharge a battery is inversely proportional to the discharge rate.

• NC is a charge or discharge rate which is N times the rated current capacity of the battery where N is a number (fraction or multiple)
• C_N is the battery capacity in Ampere Hours which corresponds to complete discharge of the battery in N hours (N is usually a subscript). Also written as the N-Hour rate.

Discharge or charge current, in amperes, expressed in multiples of the rated capacity. For example, C/10 discharge current for a cell rated at 1.2 Ah is: 1.2 Ah/10, or 120 mA.

The expected life time duration of a cell whether it is active use or in storage

A device or chamber for measuring the heat generated by objects placed inside it.

Controller Area Network The automotive industry standard for on-board vehicle communications. It is a two wire, serial communications bus which is used for networking intelligent sensors and actuators

A measure of the ability of a device to store charge per unit of voltage applied across the device. C=Q/V Farads. The capacitance of a parallel plate capacitor is given by C = ε A/d where e is the permittivity of the dielectric, A is the area of the plates (electrodes) and d the distance between them.

1 Farad = 1 Coulomb per Volt. (Q / V) The current through the capacitor is given by the relationship i =C ^d/_dtV(t)

A passive electrical device that stores energy in an electric field.

The electric energy content of a battery expressed in "Watt hours". Batteries with the same output voltage also use "Ampere hours" for comparing capacities.

A correction factor applied to the rating of a battery if discharged under different C-rates from the one rated.

A chemical agent which promotes or influences a chemical reaction without itself being permanently changed by the reaction. Used in recombinant cells and fuel cells.

The electrode in an electrochemical cell where reduction takes place, gaining electrons. During discharge the positive electrode of the cell is the cathode. During charge the situation reverses and the negative electrode of the cell is the cathode.

Particles in the electrolyte of a galvanic cell carrying a positive charge and moving towards the cathode during operation of the cell. See also anion

A measure used to specify the cold cranking capability of automotive SLI batteries. For Lead Acid batteries it is the constant current a battery can deliver during a continuous discharge over a period of 30 seconds at -18°C without the terminal voltage dropping below a minimum of 1.2 Volts/cell.

The CE marking indicates that the product has been designed and manufactured in conformity with the essential requirements of all relevant EU directives, and submitted to the relevant conformity assessment procedure.

A closed electrochemical power source. The minimum unit of a battery.

The process used during charging to ensure that every cell is charged to the same state of charge. Also called "Equalization".

The active materials used in the energy cell.

A condition which may occur in multi cell series chains in which an over discharge of the battery can cause one or more cells to become completely discharged. The subsequent volt drop across the discharged cell effectively reverses its normal polarity.

The process of replenishing or replacing the electrical charge in a rechargeable cell or battery. See also Electric charge.

The ability of a secondary cell to convert the active material to a dischargeable form. A charge acceptance of 90% means that only 90% of the energy can become available for useful output. Also called Coulombic Efficiency or Charge Efficiency. See alternative definition below.

The particle carrying the electrical charge during the flow of electrical current. In metallic conductors the charge carriers are electrons, while ions carry the charges in electrolyte solutions.

The ability of a battery to retain its charge in zero current conditions. Charge retention is much poorer at high temperatures. See also Self Discharge.

The ratio (expressed as a percentage) between the energy removed from a battery during discharge compared with the energy used during charging to restore the original capacity. Also called the Coulombic Efficiency or Charge Acceptance. See alternative definition above.

A power supply which uses capacitors instead of inductors to store and transfer energy to the output. A voltage doubler or tripler.

The current at which a cell or battery is charged. Generally expressed as a function of rated capacity C.

The movement of electrical charge from one part of the system to another, occurring through the drift of ions under the influence of electrical potential difference. Also called Electromigration.

The available or remaining capacity of a battery expressed as a percentage of the rated capacity.

Atoms, molecules, molecular fragments, ions, etc., as entities being subjected to a chemical process or to a measurement.

A small mechanical switch which interrupts the current through an energy cell if the internal pressure exceeds a predetermined limit. Usually applied in small cells only.

Small cylindrical cell with a disc shape.

Cycle charging and discharging to ensure that formation (see below) is complete when a cell enters service or returns to service after a period of inactivity.

Strictly speaking the Conductance applies to resistive circuits and is the reciprocal of the Resistance. Battery manufacturers have their own definition which applies to the frequency dependent elements of the circuit, that is - C= I/E where C is the conductance, I is the test current applied to a component (the cell) and E is the in phase component of the ac voltage E producing it.(Compare with Ohm's Law R=E/I) Measuring the conductance of a battery gives a good indication of its state of health.

Plastic materials which have some of the properties of metals. Used as solid electrolytes in batteries. Also used in the construction of fuel cell membranes, capacitor electrodes and in applications requiring anti-static plastics. See also Polymer below.

A charging scheme which maintains the current through the cell at a constant value.

A charging scheme which maintains the voltage across the battery terminals at a constant value.

The battery output terminals.

The percentage of the input energy of a process that is converted to energy of the desired type.

An electrical circuit which accepts a DC input and generates a DC output of a different voltage, usually achieved by high frequency switching action employing inductive and capacitive filter elements.

A unit of electric charge. One coulomb (1C) is equal to the charge transferred by a current of one ampere in one second.

A method of determining the state of charge of a battery by integrating the ingoing and outgoing discharge currents of a battery over time.

The ratio (expressed as a percentage) between the energy removed from a battery during discharge compared with the energy used during charging to restore the original capacity. Also called Charge Efficiency or Charge Acceptance.

A dramatic initial voltage drop when a battery is suddenly called upon to supply a heavy load. The voltage recovers after a short time once the electro-chemical discharge process stabilizes.

The temperature below which a superconducting material must be cooled in order to exhibit the property of superconductivity. See below.

The Canadian Standards Association is a not-for-profit membership-based association serving business, industry, government and consumers in Canada and the global marketplace.

The temperature above which a ferromagnets and some other materials undergo a sharp change in their magnetic properties losing their ability to possess a net spontaneous or remanent magnetization in the absence of an external magnetic field.

The flow of electricity expressed in amperes. Current refers to the quantity or intensity of electricity flow, whereas voltage refers to the pressure or force causing the electrical flow.

The maximum current drain under which the particular battery will perform adequately under a continuous drain.

A current shunt is an low value resistance, whose value is accurately known, placed in series between the battery and the load. The voltage drop across the shunt is used to determine the value of the current using Ohm's Law. Used in series, it is not a shunt in the literal sense of the word. Its name derives from the fact that early ammeters could not handle high currents and the shunt was used to bypass most of the current around the meter.

The specified voltage at which the discharge of a cell is considered complete. See also End Voltage and Termination Voltage.

Constant Voltage Transformer

A single charge and discharge of a battery.

The number of cycles a battery can perform before its nominal capacity falls below 80% of its initial rated capacity. See also Float life below.

A cell in which the electrodes are rolled up in a spiral and placed into a cylindrical container.

A device which converts a digitally coded signal into an equivalent analogue signal.

Direct Current. Electrical current that flows in one direction.

An electronic circuit which takes a DC input voltage and converts it to a different, desired DC output voltage.

A battery designed to be discharged to below 80% Depth of Discharge. Used in marine, traction and EV applications.

Discharge of at least 80% of the rated capacity of a battery.

The voltage drop which occurs in some cells, notably NiCd, which indicates that the cell is fully charged.

The formation from small crystals in the electrolyte of tree like structures which degrade the performance of the cell.

The ratio of the quantity of electricity or charge removed from a cell on discharge to its rated capacity.

The expected lifetime of a power supply during which it will operate to its published specifications.

The property of a substance which is repelled instead of attracted by a magnet. A diamagnetic material will be repelled from a magnet no matter what pole it is near. It is exhibited by all common materials, but is very weak and often swamped by stronger paramagnetic or ferromagnetic effects. Metals such as bismuth, copper, gold, silver and lead, as well as many nonmetals such as graphite, water and most organic compounds are diamagnetic. See also Ferromagnetism and Paramagnetism.

A nonconductor of electricity, such as an insulator, or a substance in which an electric field can be maintained with a minimum loss of power. The material used between two conducting plates to form a capacitor. When a dielectric or insulator is placed in an electric field, electric charges do not flow through the material but shift only slightly from their average equilibrium positions causing the dielectric to become polarized with a positive charge on one side and a negative charge on the other.

Used to determine the ability of an insulator to store electrical energy. The dielectric constant is the ratio of the capacitance induced by two metallic plates with an insulator between them to the capacitance of the same plates with air or a vacuum between them.

The change from chemical energy within the cell into electrical energy to operate a external circuit.

The amount of energy taken from the battery when discharged at the rated current and ambient temperature until the discharge end voltage is reached. Generally expressed in units of Watt hours (or Ampere hours for batteries with the same voltage).

The current delivered by the cell during discharging. Expressed in Amperes or multiples of the C rate.

The voltage between the terminals of a cell or battery under load, during discharge.

Declaration of Conformity, in which a manufacturer declares that a product conforms to a specific standard.

Depth of Discharge (see above)

In a voltage regulator, the lower limit of the AC input voltage where the power supply just begins to experience insufficient input to maintain regulation. The dropout voltage for linears is quite load dependent. For most switchers it is largely design dependent, and to a smaller degree, load dependent.

A Leclanché cell with a gel electrolyte.

Dynamic Stress Test. Accelerated battery life tests specified by the USABC. Cycling down to 80% DOD twice per day at different temperatures.

The rate of change of temperature with time. The rapid rate of temperature rise is used to detect the end of the charging cycle in NiMH batteries.

The load current or power a battery is expected to supply for specified time periods.

Discharge or charge power, in watts, expressed as a multiple of the rated capacity of a cell or battery which is expressed in watt-hours. For example, the E/10 rate for a cell or battery rated at 23.4 watt-hours is 2.34 watts. (This is similar to the method for calculating C-Rate.)

The United Nations Economic Commission for Europe specification for urban driving cycle simulation.

The ratio of total output power to input power, expressed as a percentage. This is normally specified at a full load and nominal voltage.

elastic or plastic materials that resemble rubber which resume their original shape when a deforming force is removed.

The electrostatic equivalent of the permanent magnet. Dielectric materials that have been permanently electrically charged or polarized.

physical property of matter which causes it to experience a force when near other electrically charged matter. The charge may be positive or negative. Similar charges repel each other while opposite charges attract each other. The unit of electric charge is the Coulomb (C).

the flow of electrons through conductive materials and devices.

The weight of a substance which is deposited by the passage of one coulomb of current.

Conducting element within a cell in which an electrochemical reaction occurs.

The voltage developed by a single electrode, determined by its propensity to gain or lose electrons.

Chemical modifications, oxidation and reduction produced by passing an electric current through an electrolyte. See also Faraday's Law of Electrolysis

A substance which dissociates into ions (charged particles) when in aqueous solution or molten form and is thus able to conduct electricity. It is the medium which transports the ions carrying the charge between the electrodes during the electrochemical reaction in a battery.

The ability of an electrical source to deliver energy. It is the difference of potentials which exists between the two electrodes of opposite polarity in an electrochemical cell. Also known as the Cell Voltage. The unit of EMF is the Volt.

A special-purpose computer system, which is completely encapsulated within the device it controls, usually performing a limited range of specific pre-determined tasks. This allows the use of simpler or cheaper dedicated microprocessors providing only the minimum functionality required by the application, or alternatively the entire processing power of the microprocessor can be focused on a single task. Battery Management Systems will normally be implemented with an embedded system.

Electromagnetic compatibility (EMC) is the ability of electronic and electrical equipment and systems to operate without adversely affecting other electrical or electronic equipment or being affected by other sources of electromagnetic interference. (RFI)

Electromagnetic interference. EMI is unwanted noise present on a power line.

The prescribed voltage that indicates that the discharge is complete. (see also Cut-off voltage)

Describes a chemical action in which heat is absorbed.

The output capability of a cell/battery, usually expressed in watt-hours.

The absolute amount of energy stored in a battery expressed in Wh or Joules.

The amount of energy stored in a battery. It is expressed as the amount of energy stored per unit volume or per unit weight (Wh/L or Wh/kg).

The amount of energy released or absorbed by a chemical reaction. The "Free Enthalpy" (also called the " Change in Gibbs Free Energy") in a reaction is the maximum amount of chemical energy available from a system that can be converted into electrical or mechanical energy and vice versa. (Discharge and Charge respectively.)

A measure of the disorder of a system. Used as a measure of heat content.

Electronically Erasable Programmable Read-Only Memory. Re-writable memory that does not lose data if power is lost to the system (non-volatile). Available in three types:

OTP One Time Programmable non-erasable.

Windowed (ultraviolet light erasable) used for prototyping and development work.

EEPROM Electronically Erasable Programmable Read-Only memory.

The process of bringing every cell in a battery chain to the same state of charge (SOC).

Electron Spectroscopy for Chemical Analysis. Equipment using x-ray irradiation to identify the presence of individual chemical elements particularly for surface coatings and thin films where it can be used for selected element depth profiling. A machine typically costs about $750,000.

Electrostatic Discharge

Extra Urban Driving Cycle. European additional specification for urban driving cycle simulation.

The Association of European Storage Battery Manufacturers. (Mainly Lead Acid)

A mixture in such proportions that the melting-point is as low as possible, the constituents melting simultaneously.

Electric Vehicle

Commonly describes the discharging to one volt per cell and subsequent charging. Used to maintain or condition NiCad and NiMH cells.

Describes a chemical action in which heat is produced.

The charge in Coulombs necessary to change the potential between the plates of a capacitor by 1 volt.1 Farad = 1 Coulomb per Volt. (Q / V)

An enclosure with no apertures (holes, slits, windows or doors) made of a perfectly conducting material. No electric fields are produced within the Faraday cage by the incidence of external fields upon it or by currents flowing on the perfect conductor such that the perfectly conducting enclosure is a perfect electromagnetic shield.

The magnitude of electric charge per mole of electrons or protons. It is equal to Avogadro's Number times the charge on the electron. F= N_A.e

The mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electrical charge (measured in Coulombs) transferred at that electrode.

The induced EMF in a closed circuit is proportional to the rate of change of the magnetic flux through the circuit. See also Inductance.

Charging in less than one hour at about 1.0C rate. Needs special charger.

The Federal Communications Commission is an independent United States government agency charged with regulating interstate and international communications by radio, television, wire, satellite and cable.

A statement of compliance with US FCC class "B" limits of radio frequency emission, which is issued by the FCC and accompanied by a FCC "registration" or "ID" number. Certified equipment must be marked with the ID number.

The property of a substance which is attracted to a magnet. Iron, cobalt, nickel, gadolinium, dysprosium and alloys containing these elements are ferromagnetic. See also Diamagnetism and Paramagnetism.

A semiconductor device designed for fast, current switching applications.

Instructions programmed into a micro-controller that controls its operation. A combination of hardware and software.

A fault tolerant, high speed data communications bus designed for complex automotive control applications.

An arrangement in which the battery and the load are permanently connected in parallel across the DC charging source, so that the battery will supply power to the load if the charger fails. Compensates for the self-discharge of the battery.

The expected lifetime in hours of a battery when used in a float charge application. See also Cycle life above.

In "flooded" batteries, the oxygen created at the positive electrode is released from the cell and vented into the atmosphere. Similarly, the hydrogen created at the negative electrode is also vented into the atmosphere. This can cause an explosive atmosphere in an unventilated battery room. Furthermore the venting of the gasses causes a net loss of water from the cell. This lost water needs to be periodically replaced. Flooded batteries must be vented to prevent excess pressure from the build-up of these gasses. See also Sealed Lead Acid (SLA) Cells which overcome these problems.

A battery in which the electrolyte flows or is pumped through the electrodes.

A flywheel stores kinetic energy in a high speed (up to 100,000 rpm) rotating cylinder and is "charged" and "discharged" via an integral motor/generator. High power availability but low capacity.

Electrochemical processing of a cell electrode (or plate) between manufacturing and first discharge, which transforms the active material into its useable form.

Field Programmable Gate Array. A microchip which can be made with thousands of programmable logic gates. Often used for prototype or custom designs, they permit short development times and low production costs.

Federal Urban Driving Schedule specification for urban driving cycle simulation.

An electrochemical generator in which the reactants are stored externally and may be supplied continuously to a cell.

An indication of the State of Charge (SOC) or how much charge is remaining in a battery. Also called a Gas Gauge.

A method of deriving precise answers from vague data.

An electrolytic cell in which chemical energy is converted to electrical energy on demand.

The separation and identification of individual chemical components from a sample. A typical machine costs over $250,000.

An electrical circuit which indicates the amount of charge remaining in a battery.

The generation of a gaseous product at one or both electrodes as a result of the electrochemical action. In Lead Acid batteries gassing produces hydrogen and oxygen.

A battery which uses gelled electrolyte, an aqueous electrolyte that has been fixed by the addition of a gelling agent.

See Enthalpy

A spintronic effect that produces a large change in resistance of the conducting layers that occurs when thin stacked layers of ferromagnetic and nonmagnetic materials are exposed to a magnetic field. "Giant" refers to its very large electrical signal. The technology is used to manufacture current and magnetic sensors.

The energy output per unit weight of a battery.

The power output per unit weight of a battery.

Electrical ground in an AC power system is a wire that is connected to the earth. It is intended to protect users of electrical equipment from shock hazards.

An unintentionally induced feedback loop or crosstalk caused by two or more circuits sharing a common electrical ground.

The electrochemical reaction between the electrode and the electrolyte.

When a fixed conductor carrying an electric current is placed in an external magnetic field perpendicular to the current there is voltage drop across the conductor at right angles to the current which is proportional to the magnetic field. Used to measure magnetic field strength.

An ill-defined battery characteristic. See Battery Performance.

The unit of inductance. The inductance L in a circuit =1 Henry if the rate of change of the current of 1 Ampre per second in the circuit produces an EMF of 1 Volt. 1 Henry = 1 Weber per Amp (Wb / A)

The standard unit of frequency of one cycle per second.

Hybrid Electric Vehicle (See below)

A state in which the status of the various functions of a circuit has been saved in memory and the circuit has been switched off save energy. When power is reapplied, data taken from the memory is used to restore the circuit to the status it had before switch off. See also "Standby State" below.

An ill-defined battery characteristic. See Battery Performance.

Discharge at a current of 2C or more.

The rate of doing work. 1 Hp = 746 Watts or 550 foot pounds per second.

A vehicle which has two forms of motive power one of which is electric.

A device used for measuring the specific gravity of a fluid. In the case of lead acid batteries the specific gravity provides a measure of the state of charge of the cell.

An instrument for measuring humidity. Often confused with a hydrometer.

A property of physical and chemical systems that do not instantly follow the forces applied to them, but react slowly, or do not return completely to their original state. In the case of magnetic systems, when an external magnetic field is applied to a magnetic material, the material becomes magnetized absorbing some of the external field. When the external field is removed the material remains magnetized to some extent, retaining some magnetic field. See also hysteresis in batteries.

The energy generated or lost as heat due to the internal resistance of the battery. Also known as the Joule Heating Effect.

The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes international standards for all electrical, electronic and related technologies.

Insulated Gate Bipolar Transistor. It has the output switching and conduction characteristics of a bipolar power transistor but is voltage controlled like the MOSFET giving the high current carrying capability of the bipolar transistor but the ease of control of the MOSFET.

A construction technique used in lead-acid batteries. The electrolyte (the acid) is held in place against the plates instead of being a free-flowing liquid. The two most common techniques are Gel Cell and Absorbed Glass Mat.

A measure of the response of an electric circuit to an electric current. The actual value is frequency dependent. The current is opposed by the capacitance, inductance and resistance of the circuit.

Determination of the battery's internal impedance by measuring the voltage drop across a cell when it carries a sample alternating current.

A measure of the ability of a device to store magnetic flux per unit of rate of change of current passing through the device. Measured in Henries. 1 Henry = 1 Weber per Amp (Wb / A) See also Faraday's Law of Induction. The voltage across the inductor is given by the relationship v = - L ^d/_dtI(t)

A charger in which the charging current is induced by an external induction coil into a secondary transformer winding housed within the battery together with rectifying and charge control circuits.

A passive electrical device that stores energy in a magnetic field.

The spectrum of the heat radiated by a warm body.

A substance added to the electrolyte to prevent or slow down an unwanted electrochemical process. Used to prevent corrosion of the electrodes or the formation of dendrites.

Plastic parts containing metal inserts used to simplify product assembly and reduce costs. Inserts made from metal or other materials are placed in the mould prior to the injection of plastic. The plastic flows around the inserts and fixes their position.

Battery containing circuitry enabling some communication between the battery and the application or with the charger.

Charger which is able to react to inputs from an intelligent battery to control or optimize the charging process.

A system for reducing the demands that power hungry applications place on the battery.

This insertion of ions into the crystalline lattice of a host electrode without changing its crystal structure.

Resistance to the flow of AC current within a cell. It takes into account the capacitive effect of the plates forming the electrodes.

Resistance to the flow of DC electric current within a cell, causing a voltage drop across the cell in closed circuit proportional to the current drain from the cell. A very low internal impedance is usually required for a high rate (high power) cell.

An electrical circuit which generates a sine-wave output (regulated and without breaks) using the DC current supplied by the rectifier-charger or the battery. The primary elements of the inverter are the DC/AC converter, a regulation system and an output filter.

An atom or group of atoms which is electrically charged. Depending on how they were created - through release or absorption of electrons - ions can be either positively charged (Cations) or negatively charged (Anions). See also Ionization.

Ingress Protection Rating. It consists of the letters IP followed by two digits. The first digit represents the degree of protection against dust and solids. The second digit represents the degree of protection against moisture and water.

The voltage drop across a battery due to its internal impedance. See also Ohmic loss below.

A network of national standards institutes from 148 countries working in partnership with international organizations, governments, industry, business and consumer representatives.

Atoms of the same element with the same atomic number ( the same number of protons) but with different numbers of neutrons an hence different weights. See also allotrope.

The flow of electric current through nonconductive material when placed between two superconductors. Used to detect very weak magnetic fields.

"J" A measure of work, energy or cell capacity. For electrical energy, one Joule is one Amp at one Volt for one Second, or one Watt-second. 1 Wh = 3.6kJ. For mechanical energy one Joule is a force of one Newton acting over one metre i.e. One newton metre.

The I²R loss or heating effect of a current I flowing through a resistance R.

A mathematical technique for deriving accurate information from inaccurate data.

An electrical circuit for measuring very low impedances such as battery internal impedance, contact resistance and resistance of circuit elements such as wires and cables. Also known as the Kelvin Connection for voltage sensing.

Plug and socket pairs with a unique mechanical profile which can only be mated with each other in a particular orientation and which do not allow mating with connectors of a different design.

An LDO is a type of linear regulator. Dropout voltage is the minimum input to output voltage differential required for the regulator to sustain an output voltage within 100mV of its nominal value.

The escape of electrolyte to the outer surface of the battery or cell.

A zinc carbon or zinc chloride cell.

The total amount of energy in Watt Hours which can be taken out of a rechargeable battery over all the cycles in its lifetime before its capacity reduces to 80% of its initial capacity when new.

Local Interconnect Network An automotive industry standard for on-board vehicle communications. It is a single wire, serial communications bus which is used for networking intelligent sensors and actuators.

Charger which uses a series regulator. The simplest and cheapest type but less efficient than a Switch mode charger.

A linear, or Series, regulator is a voltage regulator which uses a transistor or FET in series with the load, operating in its linear region, to subtract excess voltage from the applied input voltage, producing a regulated output voltage.

A secondary lithium cell in which both the negative and positive electrodes are lithium insertion (intercalation) compounds. Also known as rocking chair, shuttlecock or swing cell.

A lithium ion cell with a solid polymer electrolyte.

The discharge current provided by a battery, or drawn by a battery powered device.

An ill defined battery characteristic. See Battery Performance.

A measure of the magnetic field surrounding a wire (or moving charge). H = I / (2 Π r) Amps per meter, where I is the current in the wire and r the distance from the wire.

( Φ ) A measure of the magnetic field strength. Measured in Webers.

The magnetic flux per unit area. B = (Φ / A) Teslas. The flux density resulting from a magnetic field is given by B = µH where µ is the permeability of the medium.

A method of looking inside the human body without using surgery, harmful dyes or x-rays based on Nuclear Magnetic Resonance (NMR).

The production of electricity by passing a conducting fluid or plasma through a magnetic field.

is the strength of a magnetic field, or magnetic potential, in a current carrying coil of wire. It is the work that would be required to carry a hypothetical isolated magnetic pole of unit strength completely around a magnetic circuit and is equivalent to the current I multiplied by the number of turns N in the coil producing the field. It is expressed in units called ampere-turns (At). The MMF = ampere-turns = NI

A device which produces a mass spectrum of a sample to find out its composition by ionizing the sample and separating ions of differing masses and recording their relative abundance by measuring intensities of ion flux. Mass spectroscopy allows detection of compounds by separating ions by their unique mass. A typical machine costs around $250,000.

Charging by replacing one or more of the active chemicals in the cell.

When a superconducting material is cooled below its critical temperature it will exclude or repel a magnetic field. A magnet moving by a conductor induces currents in the conductor. This is the principle upon which the electric generator operates. But, in a superconductor the induced currents exactly mirror the field that would have otherwise penetrated the superconducting material causing the magnetic field to be excluded and magnet to be repulsed. This phenomenon is known as diamagnetism (see above) and is so strong that a magnet can actually be levitated over a superconductive material.

Reversible, progressive capacity loss in nickel based batteries found in NiCad and to a lesser extent in NiMH batteries. It is caused by a change in crystalline formation from the desirable small size to a large size which occurs when the cell is recharged before it is fully discharged.

A metallic compound which is able to absorb hydrogen. Used as the negative electrode (anode) of a Nickel Metal Hydride battery.

Rapid, shallow charge and discharge cycles which occur in automotive battery applications, particularly those which involve regenerative braking.

Motor Industry Software Reliability Association.

The mass in grams of one mole (or 6.02 x 1023 molecules) of any chemical compound.

The amount of substance of a system that contains as many "elemental entities" (e.g., atoms, ions, electrons, molecules) as there are atoms in 12 grams of carbon-12 (Avogadro's number of particles). It is an amount, not a physical quality. 1 mole of a pure substance has a mass in grams equal to its molecular mass (M).

A small molecule that may become chemically bonded to other monomers to form a polymer. From Greek mono "one" and meros "part".

The microstructure of the solid phases of materials. The grain shapes and structure of crystals of the chemical components of a battery.

A Field Effect Transistor made using Metal Oxide Semiconductor technology. Controlled by voltage rather than current like a bipolar transistor. MOSFET's have a significantly higher switching speed than bipolar power transistors. Suitable for high power circuits, they generate almost no loss (little heat generation), enabling fast response, excellent linearity, and high efficiency. The positive temperature coefficient inhibits thermal runaway. (Degrades to an SFET - Smoke and Fire Emitting Transistor if subject to excessive voltages). See also IGBT.

Information provided by battery or cell manufacturers about any hazardous materials used in their products.

Mean Time Between Failure. A measurement of the relative reliability of a power supply based upon actual operating data or calculated according to MIL-HDBK-217.

A multiplexer is a device which enables several communications links or signals to share a single communications channel. At the receiving end of the link a demultiplexer separates the signals again. Various coding schemes are possible which enable the signals to be transmitted simultaneously or sequentially.

From the Latin word meaning "dwarf". One billionth or 10 ^-9. One micron = 1000 nanometers. One nanometer is about the diameter of 3 to 6 atoms (depending on the element).

Very small battery built using nano technology. Of microscopic size 1 micron diameter they deliver 3.5 volts. The electrodes are ceramic or carbon particles and the electrolyte is a solid polymer impregnated in an aluminum oxide membrane.

Nanomaterials (nanocrystalline materials) are materials possessing grain sizes on the order of a billionth of a meter. Used for electrodes and separator plates in NiMH and Lithium ion batteries and also in supercapacitors. Their foam-like (aerogel) structure provides a very large effective surface area which can hold considerably more energy than their conventional counterparts.

The NDV is the drop in the battery voltage which occurs when NiCad or NiMH cells reaches their fully charge state. Used to detect the end of the charging cycle in NiCd cells/batteries.

The electrode which has a negative potential. The anode.

The National Electric Manufacturers Association in the USA publish standards for batteries jointly with ANSI. (See above)

Used by cell designers to calculate the voltage of a chemical cell from the standard electrode potentials, the temperature and to the concentrations of the reactants and products.

A powerful data modeling tool that is able to capture and represent complex input/output relationships. It is used as a basis for self learning systems.

Used to indicate the average capacity of a battery. It is the average capacity when batteries are discharged at 0.2C within one hour of being charged for 16 hours at 0.1C and 20± 5°C. (or discharge at 0.05C for automotive batteries - SAE) Definition depends on the conditions. See Ampere Hours Ah above.

Used to indicate the voltage of a battery. Since most discharge curves are neither linear nor flat, a typical value is generally taken which is close to the voltage during actual use.

Non-Recurring Engineering costs. A one time charge for design and implementation of custom battery packs or other products.

National Stock Number. Assigned to cells, batteries and power equipment purchased by the Department of Defense or other military/government agencies.

A thermistor with a negative temperature coefficient, whose resistance decreases with increasing temperature.

Occurs when the atomic nucleus splits into two or more smaller nuclei plus some by-products. These by-products include free neutrons and photons (usually gamma rays). Fission releases substantial amounts of energy (the nuclear binding energy ). The neutrons released by the fission process may collide with other nuclei causing them in turn to undergo fission initiating to a chain reaction.

A process in which two nuclei join together to form a larger nucleus and releasing energy. It takes considerable energy to overcome the repulsion between the two positively charged nuclei to force them to fuse. The fusion of lighter nuclei, which creates a heavier nucleus and a free neutron, will generally release even more energy than it took to force them together. It is an exothermic process which could produce self-sustaining reactions.

The interaction of atomic nuclei placed in an external magnetic field with an applied electromagnetic field oscillating at a particular frequency. Magnetic conditions within the material are measured by monitoring the radiation absorbed and emitted by the atomic nuclei. Used in MRI scanners and as a spectroscopy technique to obtain physical, chemical, and electronic properties of molecules.

A company with the prime responsibility for conceiving, designing, manufacturing and distributing a particular product line.

A power supply that receives its input power from the AC line, without using a 50/60 Hz power transformer prior to rectification and filtering.

The voltage drop across the cell during passage of current due to the internal resistance of the cell. Also known as IR loss or IR drop.

The voltage of a cell or battery with no load attached measured with a voltmeter at room temperature.

The minimum and maximum input voltage limits within which a power supply will operate to specifications.

The range of ambient temperatures within which a battery/power supply can operate.

Voltage between the two terminals of the battery with a load connected.

A high gain DC amplifier with a voltage gain of 100 to 100,000 or more and a very high (ideally infinite) input impedance and very low (ideally zero) output impedance. Op-amps are the basic building block of linear integrated circuits used for analogue circuit applications. They have positive and negative inputs which allow circuits which use feedback to achieve a wide range of functions.

Intermittent charging from sources whenever or wherever power is available.

Also called Opto-coupler. An isolation device using optical techniques (an LED transmitting across a small gap to a photocell) to isolate the electrical connections between a transmitter and a receiver. Used to pass signals between high voltage and low voltage circuits and to replace switches and relays. Having no electrical connection they also help to cut down on ground loops.

The diffusion of a solvent through a semi permeable membrane from a region of low solute concentration to a region of high solute concentration. The semi permeable membrane is permeable to the solvent, but not to the solute, resulting in a chemical potential difference across the membrane which drives the diffusion. The solvent flows from the side of the membrane where the solution is weakest to the side where it is strongest to equalize the concentration on both sides.

The maximum current which can be continuously drawn from the output of a power supply.

The ratio of change in input voltage to charge in load current.

The specified level of power of which a power supply is capable. Typically, power supplies have a continuous rating and a peak rating. These are usually a function of the ambient temperature.

Continuous charging of the battery after it reaches full charge. Generally overcharging will have a harmful influence on the performance of the battery which could lead to unsafe conditions. It should therefore be avoided.

Exceeding the manufacturer's recommended maximum discharge current for a cell or battery.

A circuit that protects the power supply and computer from excessive current, including short-circuit current.

Discharging a battery below the end voltage or cut-off voltage specified for the battery.

An injection moulding technique used to encapsulate and protect components or small sub-assemblies, usually by moulding a soft, flexible plastic over the components which must be able to withstand the temperatures and pressures of the moulding process. Used for cable connectors, gaskets, and for incorporating small components into cables. Two shot moulds may be used to provide soft plastic grips over a hard plastic shell.

The difference between the actual potential at which an electrochemical reaction occurs, and its theoretical equilibrium potential.

A power supply feature that shuts down the supply, or clamps the output, when its voltage exceeds a preset level.

The loss of electrons by a chemical species.

In a battery, the mechanical structure used to contain and protect its components (cells, electronic circuits, contacts etc.).

The connection together of, two or more, similar cells to form a battery of higher capacity by connecting together all the cell terminals of the same polarity.

The property of a substance which is attracted to a magnet. It is similar to ferromagnetism except that the attraction is weaker. When a paramagnetic material is placed in a strong magnetic field, it becomes a magnet as long as the strong magnetic field is present. But when the strong magnetic field is removed the magnetic effect is lost. Below the substance's Curie temperature a paramagnetic material becomes ferromagnetic. Paramagnetism is exhibited by materials containing transition elements, rare earth elements and actinide elements. Liquid oxygen and aluminum are also examples of paramagnetic materials. See also Diamagnetism and Ferromagnetism.

A resistive layer that forms on the electrodes in some cells after prolonged storage impeding the chemical reaction. This barrier must be removed to enable proper operation of the cell. Applying charge/discharge cycles often helps in preparing the battery for use. In other applications, passivation is used as a method of shielding a metal surface from attack.

Protection circuit module.

The maximum amount of current that a source can output for brief periods of time.

A tabular display of the known chemical elements. The elements are arranged by electron structure so that many chemical properties vary regularly appearing in groups with common properties across the table. Each element is listed by its atomic number and chemical symbol.

The charging current which can safely be continuously supported by the battery, regardless of the state of the charge.

The measure of the characteristic of a medium to support the formation of a magnetic field. It indicates degree of magnetization that a material obtains in response to an applied magnetic field. It is measured in units of Henries per metre (H / m).

The measure of the characteristic of a medium to resist the formation of an electric field. It gives an indication of how much electrical charge a material can store in a given volume. It is measured in units of Farads per metre (F/ m).

A value that indicates how well a battery performs under heavy currents. A value close to 1 indicates that the battery performs well; the higher the number, the more capacity is lost when the battery is discharged at high currents. The Peukert number of a battery is determined empirically.

An empirical formula that approximates how the available capacity of a battery changes according to the rate of discharge. The equation shows that at higher currents, there is less available energy in the battery.

(potential (of) hydrogen) is a logarithmic measure of the concentration of hydrogen ions (H + ) in a solution and, therefore, its acidity or alkalinity (basicity). pH = -log[H + ]

The "pH" scale extends from 0 to 14 (in aqueous solutions at room temperature). A pH value of 7 indicates a neutral (neither acidic nor basic) solution. A pH value of less than 7 indicates an acidic solution, the acidity increases with decreasing pH value. A pH value of more than 7 indicates an alkaline or basic solution, the alkalinity or basicity increases with increasing pH value.

A device that directly converts the energy in light into electrical energy. Also called a photocell, a solar cell or a PV cell.

The generation of an electromotive force as a consequence of the absorption of radiation. In practice a current which flows across the junction of two dissimilar materials when light falls upon it.

A selected cell whose condition is assumed to indicate the condition of the entire battery.

The electrodes used in a flat plate cell.

Partnership for a New Generation of Vehicles. A partnership between government, industry and academia in the USA to improve all aspects of automotive design in which batteries figure highly.

The change in the potential of a cell or electrode from its equilibrium value caused by the passage of an electric current through it. There are two irreversible electrochemical components, the "electrode polarisation" at the electrodes and the "concentration polarization" in the electrolytic phase plus an ohmic loss component due to the electrical resistance of the cell. Also due to the build up of gas bubbles on the electrodes.

Reversal of the polarity of a battery or cell due to over discharge.

Strictly it is a substance made of long repeating chains of molecules called monomers which may be identical or different. The term polymer is often used in place of plastic, rubber or elastomer. In battery technology polymer usually refers to a solid (plastic) ionic conductor that is an electrical insulator but passes ions. (See also Conducting Polymer above.)

The ability of solid materials or compounds with the same chemical composition to exist in more than one form or crystal structure giving rise to materials with different physical or chemical properties. When the material consists of a single element, the property is known as allotropy.

A resettable fuse. (See below)

The electrode which has a positive potential. The cathode. Electric current from this electrode flows into the external circuit.

A battery or cell contained in a flexible metal foil pouch.

The amount of power available from a battery. It is expressed as the power available per unit volume or per unit weight (W/L or W/kg).

A source for the power needed for active electronic circuitry. Can consist of one or more batteries, or an electronic circuit which converts AC line voltage to the type of power required by a particular device.

A high current, bipolar transistor controlled by the current through the gate. Used in linear (series) regulators as the voltage dropper between the unregulated voltage input and the regulated output. Also used as a high current switching device in control and protection circuits. Needs a high current to turn it on and is slow to turn off and its negative temperature coefficient makes it prone to thermal runaway. For these reasons it was mostly super ceded by MOSFETs in high power battery switching applications. See also Thyristor and IGBT.

The standard proposed for next generation of automotive batteries. Nominally 42 Volt systems.

Parts Per Million

A Polymeric Positive Temperature Coefficient device. It is a non-linear thermistor, more commonly called a resettable fuse.

A battery that is non-rechargeable.

A slim rectangular sealed cell in a metal case. The positive and negative plates are stacked usually in a rectangular shape rather than rolled in a spiral as done in a cylindrical cell.

Multi-stage stamping tools for producing complex metal components from flat metal strip in a hydraulic or eccentric press. The die consists of two or more stages each of which carries out punching, drawing or folding operations with each down stroke of the press. Between each stroke, the strip moves from stage to stage through the die. Complex profiles and three dimensional shapes can be built up from a series of simpler operations which take place progressively at each stage as the strip passes through the die.

A facility incorporated into battery packs to protect the cells from out of tolerance working conditions or misuse.

A thermistor with a positive temperature coefficient, whose resistance increases with temperature.

Versatile, hybrid charger having some of the advantages of both switch-mode and linear chargers. More costly than both.

A high rate discharge, usually of 1 second or less.

Charging in three to six hours at about 0.3C rate. Needs special charger.

The current which continues to be drawn from the battery when the application it powers is in standby or hibernation mode.

The graphical illustration of the specific energy of a cell as a function of its specific power.

Rechargeable Alkaline Manganese cells.

Power systems deriving their energy from local solar or wind sources using a battery for energy storage and supplying the load through DC-DC converters or AC inverters.

When applied to cells it usually means the cells current carrying capacity.

The specified capacity of a battery.

Sealed secondary cells in which gaseous products of the electrochemical charging cycle are made to recombine to recover the active chemicals. A closed cycle system preventing loss of active chemicals. Used in NiCd and SLA batteries.

One or more deep discharges below 1.0 V/cell with a very low controlled current, causing a change to the molecular structure of the cell and a rebuilding of its chemical composition. Reconditioning helps break down large crystals to a more desirable small size, often restoring the battery to its full capacity. Applies to nickel-based batteries. See also refurbishment (below)

The lowering of the polarization of a cell during rest periods.

Reclamation of materials without endangering human health and the environment.

A contraction of the words "reduction" and "oxidation". The two chemical reactions on which cell chemistries depend.

A battery in which the chemical energy is stored in two dissolved ionic reactants separated by a membrane.

The gain of electrons by a chemical species.

The repair of worn out or damaged batteries. This is not the same as reconditioning (see above).

This uses the electrical drive motor in an electric vehicle to act as a generator returning energy to the battery when overdriven mechanically by the vehicle wheels. This provides a powerful braking effect and at the same time captures energy which would otherwise be wasted or dissipated in the brakes.

A high power Sodium Polysulfide Bromine "Flow Battery".

See Voltage regulator.

A mechanical switch operated by a solenoid.

The resealable vent internal to a cell to release excessive internal pressure.

Batteries which are stored in an inactive state without their electrolyte. They are only activated when needed by the introduction of the electrolyte. See also Water-activated batteries and Ampoule batteries.

The number of minutes at which the battery can be discharged at 25 Amps and maintain a terminal voltage higher than 1.75 volts per cell, on a new, fully charged battery at 80degrees Fahrenheit(27C). Defines a battery's ability to power a vehicle with an inoperative alternator or fan belt. Used for comparing automotive SLI batteries.

A fuse which protects against excessive current and temperature by interrupting the flow of current. After opening it will reset after the fault conditions have been removed but only after it has cooled. It requires no manual resetting or replacement. The "Polyswitch" is an example of this.

Resistance welding is a process used to join metallic parts with electric current. There are several forms of resistance welding, including spot welding, seam welding, projection welding, and butt welding.

Interruptions to the charging process to allow the chemical reactions in the battery to stabilise.

A chemical reaction which can be reversed to reconstitute the original components.

Radio Frequency Interference. Transmitted/emitted RFI affects other external equipment. Susceptibility measures the immunity of equipment from received RFI. See also EMC and Electromagnetic Radiation.

Radio Frequency Identification. Small tags incorporating a radio transmitter which can be used to identify or track items of value.

A lithium ion cell.

A standard for serial transmission of data between two devices.

A standard for serial transmission of data between multiple devices.

Society of Automotive Engineers. The SAE Technical Standards Board issues and recommends industry standards.

A safety mechanism that is activated when the internal gas pressure rises above a normal level.

The repetition frequency at which digital samples are taken of an analogue quantity.

A cell which remains closed and does not release gas or liquid when operated within the limits of charge and temperature specified by the manufacturer. An essential component in recombinant cells.

A battery which can be recharged and used repeatedly.

Capacity loss during storage due to the internal current leakage between the positive and negative plates.

Apparatus used to investigate the physical structure of cell components and surfaces. They typically cost about $500,000 or more.

An insulator whose conductivity can be manipulated by the addition of impurities ( doping ), by introduction of an electric field, by exposure to light , or by other means.

A non-conductive semi-permeable film or grid to separate 2 electrodes to prevent them from contacting each other and short-circuiting but which allows the passage of ions through it.

The connection of, two or more, similar cells in a chain to form a battery of higher voltage by connecting the positive terminal of each cell to the negative terminal of the next cell.

Another name for a Linear Regulator

The period of useful life of a battery before a predetermined end point is reached.

The loss of material from the plates of Lead Acid batteries.

The duration a cell can be kept in storage and still retain its ability to give a specified performance. See also Battery Storage.

In the event that the output is shorted, this circuit will protect the power supply by limiting the amount of current flowing through the short circuit.

Terminals surrounded by an insulating shroud which prevents accidental contact with the terminal.

A device which allows electric current to pass around another point in the circuit.

A voltage regulator which uses a transistor or FET, in parallel with the load, which shorts out the excess voltage when the applied input voltage exceeds a specified limit producing a regulated output voltage. It is a simple but lousy design.

A lithium ion cell.

Heating a mixture of powdered metals, sometimes under pressure, to the melting-point of the metal in the mixture which has the lowest melting-point, the melted metal binding together the harder particles.

Equipment used for rapid prototyping. See Stereolithography Apparatus below.

Sealed Lead Acid battery. In sealed batteries the generated oxygen combines chemically with the lead and then the hydrogen at the negative electrode, and then again with reactive agents in the electrolyte, to recreate water. A recombinant system. The net result is no significant loss of water from the cell. See also Flooded Lead Acid cell.

Common automotive battery used for Starting, Lighting and Ignition.

Charging overnight in 14 to 16 hours at about 0.1C rate. Safe and simple.

An intelligent battery which contains information about its specification, its status and its usage profile which can be read by its charger or the application in which it is used.

System Management Bus. A two wire, 100 KHz, serial bus for interconnecting Smart Batteries which have built in intelligence, with their associated chargers or applications.

State of Charge. See below.

State of Health. See below.

A photovoltaic cell. Solar cells convert sunlight energy into electric current. They do not store energy.

An array of photocells providing an increased output.

A coil containing an iron plunger which moves when a current is passed through the coil.

Cells with solid electrolytes. Lithium polymer cells are examples of this technology

Same as Gravimetric Energy Density (Wh/Kg)

The ratio of the weight of a solution compared with the weight of an equal volume of water at a specified temperature. It is used to determine the charge condition in lead acid batteries.

Same as Gravimetric Power Density (W/Kg)

A technology used in solid state devices which exploits the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge. Also known as Magnet Electronics.

Battery construction in which the electrodes with the electrolyte and separator between them are rolled into a spiral like a jelly roll (Swiss roll).

Back to Top Standard Charge

The normal C/10 charge used to recharge a cell or battery in 10 hours. Other definitions (charging periods) also apply.

A fully charged battery ready to take over supplying a load in case of emergency.

A state in which the main functions of a circuit have been powered down to save energy, but power remains applied to the circuit ready to make a rapid restart. (See also "Hibernation state" above)

SOC - The available capacity of a battery expressed as a percentage of its rated capacity.

SOH - A measurement that reflects the general condition of a battery and its ability to deliver the specified performance compared with a fresh battery. It takes into account such factors as charge acceptance, internal resistance, voltage and self-discharge. It is not as precise as the SOC determination.

A Rapid Prototyping (RP) system for creating plastic parts directly from 3D CAD files. The RP model speeds design validation and is also finds use as a master pattern.

The branch of chemistry that deals with the numerical proportions in which substances react.

The length of time a cell or battery can be stored on open circuit without permanent deterioration of its performance. See also Battery Storage

Threaded bolt connectors used on high power cells

Growth of lead sulphate crystals in Lead-Acid batteries which inhibits current flow. Sulphation is caused by storage at low state of charge.

A capacitor that can store a large amount of energy. Also called Ultracapacitor or Booster capacitor.

A phenomenon occurring below a very low, characteristic critical temperature in certain materials (superconductors), characterized by the complete absence of electrical resistance and the damping of the interior magnetic field (the Meissner effect ). Superconductors can carry currents that will not decay.

Distortion of cells caused by expansion of the active chemicals due to temperature and pressure effects.

A lithium ion cell

Charger which uses a switch mode regulator. More efficient but more costly than a Linear charger.

A switching regulator is a voltage regulator which uses an output stage, switched repetitively on and off, together with energy storage components (capacitors and inductors) to generate a DC output voltage. Regulation is achieved through Pulse Width Modulation (PWM). Output voltages can be generated that are greater than or less than the input voltage and multiple output voltages can be generated with a single regulator.

A switch mode regulator.

Flat connectors used on pouch cells.

The relationship between the internal electrode potentials in a battery and the current which flows. This is an exponential relationship based on empirical results which quantifies the electrochemical reactions. It is analogous to the Arrhenius equation which quantifies the thermochemical process relating the temperature to the rate at which a chemical action progresses.

In quick chargers the charging current is is progressively reduced in a controlled way by controlling the supply voltage. In slow chargers the voltage is fixed and the charging current reduces in an uncontrolled way due to increase in the cell voltage as the charge builds up.

off - A temperature sensing method which detects heat rise in a cell at overcharge and switches the charger off or to a lower rate of charge.

The reduction in output power due to an increase in ambient temperature.

The specified ambient temperature range over which it is safe to operate the power supply.

The specified ambient temperature range in which the power supply can be stored without risk of damage.

An electronic device which provides a voltage analogue of the temperature of the surface on which it is mounted. A thermistor is an example.

The maximum voltage which can be tolerated by a cell during charging without damaging the cell. The cell voltage at which the charging process should be terminated.

The unit of magnetic flux density. 1 Tesla = 1 Weber / metre²

The amount of energy required to raise the temperature of an object by one degree Celsius. Expressed in Joules/Kg.

A safety device which interrupts a circuit when it detects excessive temperature.

A photographic technique which displays the range of temperatures of a warm body in the form of a color spectrum. Used as a design verification tool for detecting hot spots in battery and other equipment designs.

The means by which a battery is maintained within its operating temperature limits during charging and discharging.

A power supply protection circuit which shuts the power supply down in the event of unacceptably high internal temperatures.

A condition in which an electrochemical cell will overheat and destroy itself through internal heat generation. This may be caused by overcharge or high current discharge and other abusive conditions.

An electrical device whose resistance varies with temperature. They are used as temperature-measuring devices or in electrical circuits to compensate for temperature variations of other components.

Also called a Silicon-Controlled Rectifier or SCR, it is a solid-state high current semiconductor switching device similar to a diode, with an extra terminal which is used to turn it on. Once turned on, the thyristor will remain on (conducting) as long as there is a significant current flowing through it. If the current falls to zero, the device switches off. See also Power transistor.

A high power deep cycle secondary battery designed to power electric vehicles or heavy mobile equipment.

The ability of an electrical or other device to respond faithfully to sudden changes to the input conditions.

A continuous charge at low rate, balancing losses through local action and/or periodic discharge, to maintain a cell or battery in a fully charged condition. Normally at a C/20 to C/30 rate.

TÜV Rheinland Group (TUV - Technical Inspection Association) is an international service company which documents the safety and quality of new and existing products, systems and services.

Underwriters Laboratories Inc - (UL) is an independent, not-for-profit product safety testing and certification organization based in the USA. UL marking indicates that the product conforms to the safety standards laid down by Underwriters Laboratories.

Widely used, however, technically incorrect. The correct terms are UL Listed or UL Recognized.

UL grants this form of approval to equipment that will be user installed or operated and that is found to meet the safety requirements of the applicable UL standards. UL Listed products must be marked with the UL symbol.

This is a form of formal approval granted by UL to devices that are not used as free standing equipment on their own, but are to be installed into some other system by a manufacturer, electrician, or an end user.

See "Supercapacitor" above.

Ultrasonic welding involves the use of high frequency sound energy to soften or melt the thermoplastic at the joint. Parts to be joined are held together under pressure and are then subjected to ultrasonic vibrations usually at a frequency of 20, 30 or 40kHz.

Uninterruptible Power Supply

The United States Advanced Battery Consortium

The combining capacity of an atom expressed as the number of single bonds the atom can form or the number of electrons an element gives up or accepts when reacting to form a compound.

The release of excessive internal pressure from a cell in a manner intended by design to preclude explosion.

The unit of measurement defining the force needed to send one Ampere of current through a system with a defined amount of resistance. The algebraic symbol is V. Amps x Resistance = Volts (I x R = V) The voltage of batteries is quoted as "nominal" because it varies during the life of the battery and the amount and rate of current being taken from the battery.

The unit of measurement of electric potential. Voltage is the difference in electrical energy between two points.

A voltage sensing device which will end a charge or discharge at a preset voltage value.

A voltage value a battery is not permitted to rise above on charge and/or fall below on discharge.

A circuit which provides a fixed or controlled voltage output from a variable voltage input. Used in power supplies and chargers. Switching regulators , Linear regulators and Shunt regulators are the most common types.

The ratio (expressed as a percentage) between the voltage necessary to charge a secondary cell and the corresponding discharge voltage.

The energy output per unit volume of a battery.

The power output per unit volume of a battery.

Valve Regulated Lead Acid Battery

Leonard Controller - A motor-generator system which uses a AC motor driving a variable voltage DC generator which drives a DC motor to provide a variable power transmission. Used for high power load testing.

A unit of power, the rate of doing work. Watts = Amps X Volts = One Joule per second.

A measure of the energy capacity of a battery. The amount of work done in one hour. 1 Wh = 3.6 kJ.

The unit of the magnitude of the magnetic flux. A flux density of one Wb/m2 (1 Weber per square meter) is 1 Tesla

The ratio between the mechanical energy ultimately delivered to the road wheels of a vehicle and the chemical energy content of the oil consumed in providing it. It is used to compare the fuel efficiencies of different methods of powering road vehicles and takes into account the refining process, the energy loss in the distribution process (in the case of hydrogen, the energy used to compress it) and the conversion efficiency of the vehicle's power unit.

A cell with free flowing liquid electrolyte.

The use of the property of X-ray diffraction by crystals to determine their physical structure.

A desperation measure to revive a shorted cell suffering from dendrites. A very high current, low voltage pulse from a large capacitor used in an attempt to vaporize the dendrites.

A high temperature Sodium Nickel Chloride battery delivering high power.