The Battery Glossary here covers a comprehensive range of terms related to batteries, electricity, and energy storage systems. It encompasses definitions, concepts, and technical details associated with various aspects of the subject.AC: Alternating current; current flows in both directions. Household current is AC.Acid: Compound in a battery that promotes electrochemical reaction.AGM: Absorbent Glass Mat is a lead acid battery that uses a glass mat to promote the recombination of gases produced by the charging process.Allotrope: Two or more forms of the same element in the same physical state (solid, liquid, gas) that differ from each other in physical and sometimes chemical properties.Ampere-hours: Symbol Ah is a unit of charge. Example: Drawing a current of one ampere (1A) from a battery for one hour (1h) equates in one ampere-hour (1Ah).Anode: Electrode on which oxidation occurs; releases electrons on discharge. When applying power to a device (vacuum tube, diode, battery on charge), the anode is positive; taking power away on discharge turns the anode to negative.Antimony: Used in lead acid batteries to improve mechanical strengths of lead plates and enhances performance. Other uses are flame proofing, producing low friction applications, and building semiconductors.ASoC: Absolute state-of-charge; ability to take specified charge when the battery is new.ASoH: Absolute state-of-health; ability to store specified energy when the battery is new.Barrel: Measuring unit for liquids (oil); 1 barrel has 42 US gallons, 35 Imperial gallons, 159 liters.Basel Convention: International treaty to reduce the movements of hazardous waste between nations; signed in1989 in Basel, Switzerland and made effective in 1992.Battery: Electrochemical cell, or cells, connected in series (some in parallel); composed of the anode (negative electrode), cathode (positive electrode), separator and electrolyte as catalyst.Battery cycle: Charge followed by a discharge and recharge. No standard exists as to level of charge and discharge to constitute a cycle.Battery Directive 2006/66/EC: European legislation on waste batteries to protect the environment.BESS: Battery energy storage system (also known as ESS)BMS: Battery Management System used inside or outside a battery to manage charge, discharge and provide SoC; forms an essential part to assure battery longevity and safety.Bluetooth: Low-power radio communications up to 10 meters (30 feet). Bluetooth borrowed the name from Harald Bluetooth, a Danish king who lived more than 1,000 years ago.Boolean bit: System of symbolic logic devised by George Boole in the 1840s; used in computers.Button cell: Miniaturized battery also known as coin cell. Most are non-rechargeable.Calcium: Fifth most abundant element by mass in the earth crust; essential for living organisms to build bone, teeth and shells. Discovered by Humphry Davy (1778–1829). Improves mechanical strength of lead plates in lead acid batteries; enhances performance.Candela (cd): Unit of luminous intensity; agreed international name since 1967.Capacitance: Unit measuring the electrical charge in a capacitor (condenser), measured in farad (f).Capacitor: Component consisting of two conductive surfaces separated by an insulator. Passes AC; indefinite resistance for DC; voltage lags behind the current (opposite of a coil).Capacity: Electrical energy of a battery in ampere-hours (Ah). The stored energy is measured by observing the elapsed time while discharging at a constant current to the end-of-discharge voltage. The capacity is the leading health indicator of a battery.Capacity offset: Capacity correction when discharging a battery at a higher C-rate than specified.Carbon dioxide: (CO2) Odorless gas formed during combustion, respiration and decomposition of organic substances. Plants absorb CO2; excess CO2 is blamed for climate change.Cathode: Electrode in an electrochemical cell in which reduction takes place by absorbing electrons. During discharge, the cathode is positive; reverse on charge.C-code: Abbreviation for configuration code. C-code is stored in a battery adapter and configures the analyzer to the correct battery settings (Cadex systems).Cell mismatch: Cells in a battery pack that have unequal capacities, voltages or resistive values.Cell reversal: Cell polarity reverses on a deep discharge at high load. Damages affected cell.Charge: Replenishing electrical charge to a cell or battery.Chemical battery: Behavior of the actual battery as opposed to monitoring peripheral activities.Cobalt (Co): Hard, lustrous, gray metal; used in batteries, magnets, and high-strength alloys.Co-generation: Utilization of heat and kinetic force. Heat drives steam turbines; kinetic force produces electricity through a generator; charges a battery on deceleration.Coke: Derivative of coal from which most gases have been removed through heating.Coulomb: Unit of electric charge. One coulomb (1C) equals one ampere-second (1As).Coulombic efficiency, also called faradaic efficiency or current efficiency describes the charge efficiency by which electrons are transferred in a batteries.C rate: Unit by which charge and discharge times are scaled. At 1C, the battery charges and discharges at a current that is at par with the marked AhCurrent-limiting charger: Keeps current constant and allows voltage to fluctuate. (NiCd, NiMH chargers)Cycle: Charge/discharge/charge. No standard exists as to what constitutes a cycle.Cycle life: Number of cycles a battery can deliver. (End of-battery-life for portable devices is commonly set to 80%.)Cylindrical cell: Positive and negative plates are rolled up and placed into a cylindrical container.DC: Direct current; current flows in one direction. A battery delivers a DC current.DC-to-DC converter: Converts DC to a higher or lower voltage potential.Delta temperature over delta time (dT/dt): Senses rate of temperature increase over a given time rather than by measuring the absolute value; used for full charge detection of nickel-based batteryDigital battery: Peripheral that monitors battery activity associated with the smart battery.DIN, IEC: Capacity of a starter battery is measured with a 0.2C-rate (5h) discharge of a fully charged battery to 1.55V/cell or a 0.05 (20h) discharge to 1.75V/cell.DoD: Depth of discharge; 100% is full discharge; 80% is commonly used for specification.Double-layer capacitor: Electrostatic storage device utilizing the electrical double layer effect that is formed near the surface of the carbon electrode; also called supercapacitors or ultracapacitors.Driving range: EVs display the allowable driving rang range rather than capacity. As the capacity fades, battery gets charged more and discharged deeper. The full capacity is hidden.Dumb battery: Basic electrochemical battery with no electronic intelligence with which to communicate.Electrochemical impedance spectroscopy (EIS), also known as impedance spectroscopy; method to test electrochemical characteristics of a battery; EIS injects AC signals at different frequencies and analyzes the response.Electrode: Conductor or plate in a cell in which an electrochemical reaction occurs.Electrolyte: Non-metallic conductor of electricity (typically liquid) placed between positive and negative electrodes of a battery. Ion movement enables current flow.Electrolyte oxidation (EO): Formation of a restrictive film on the Li-ion cathode if the voltage is kept above 4.10V/cell. The longer the battery stays in a high voltage, the more pronounced the degradation will be.Energy: Work measures over time. Multiplying voltage x current x time = Watt-hours (Wh). Energy is also given in joules (J); 1,000 joules are 0.277Wh.Energy Cell: Battery cell designed for maximum capacity. Power density may be compromised.Energy density: Also known as volumetric energy density; specifies the amount of energy a cell can hold in volume (Wh/l). Energy density is synonymous with the runtime of a battery.Energy Star: Organization promoting energy efficiency.Exercise: In battery maintenance, one or several discharge cycles to the end-of-discharge with recharge; prevents memory buildup in NiCd and NiMH batteries.Farad (f): Charge in coulombs necessary to change the potential between the plates of a capacitor by 1V. (1 Farad = 1 Coulomb per Volt)Fast charge: 1–3 hours charge time.Float charge: Similar to trickle or maintenance charge; compensates self-discharge of lead acid battery.Flow battery: A cross between a conventional battery and a fuel cell. Liquid electrolyte of metallic salts is pumped through a core with positive and negative electrodes, separated by a membrane. The resulting ion exchange generates electricity.Frequency: Number of events in a given time. Indicates how often the AC voltage changes from positive to negative per second, or how many times a battery is cycled.Fuel cell: Device converts oxygen and hydrogen into electricity and water.Fuel gauge: State-of-charge (SoC) indicator to estimate the charge level of a battery.Fuzzy logic: Multi-valued, mathematical logic derived from blurred data derives at a voted result. Battery rapid testing, image recognition, weather forecasting and medical tests follow fuzzy logic.Graphene: Allotrope of carbon in a two-dimensional hexagonal lattice in which one atom forms each vertex; establishes the basic structural element of graphite, charcoal diamonds and more.Graphite: A form of carbon with hexagonally crystallized allotrope, used in lead pencils, lubricants, batteries and the anode of most Li-ion.Gravimetric energy density: Also known as specific energy; indicates the amount of energy a cell holds in weight (Wh/kg); synonymous with battery runtime.Halon: Agent to suppress fire. Used also for Li-ion fires.Hertz (Hz): Unit of frequency; 1Hz constitutes one full cycle per second.Hydrogen (H): Chemical element with atomic number 1; lightest and most abundant chemical element; constitutes roughly 75% of the universe’s elemental mass. Hydrogen gas becomes explosive at a concentration of 4 percent.Hydrometer: Device to measure the specific gravity of a fluid; reads state-of-charge of a lead acid and other flooded batteries.Hysteresis charge: Charger turns off at full charge and resumes after a time to compensate for parasitic loads and self-discharge.I2C: Inter-Integrated Circuit is a multi-master, multi-slave, single-ended, serial computer bus invented by Philips Semiconductor.IEC 60079: Intrinsically safe standards to prevent explosion in areas of flammable gas and dust.IEC 60086: Safety standard for primary batteries.IEC 62133: Safety requirements for sealed secondary cells/batteries for portable use.IEEE 1625: Standard for rechargeable batteries for mobile computing devices.IEEE 1725: Standard for rechargeable cells/batteries for mobile phones.Imaginary impedance: Also known as complex impedance; characterizes the electrical resistance of reactive components as a function of frequency. Rising frequency lowers the capacitive resistance and increases the inductance resistance.Impedance: Combination of capacitive, inductive and ohmic resistance; measured in ohms (R); frequency dependent.Inductance (L): Winding that causes an electromotive force when current is applied; frequency dependent; reacts opposite to a capacitor; measurement in Henry (H.Intelligent battery: Also known as smart battery; enables communication between device, charger and user.Internal resistance: Electrical resistance of a battery pack in milliohms (m). A good battery has low resistance; corrosion raises it.Intrinsically safe battery: Has built-in protection circuit to enable safe operation in a hazardous area; prevents sparks by limiting voltage and current spikes.Ion: Atom or molecule with unequal number of electrons and protons; provides a positive or negative electrical charge.Joule (J): Energy measurement: 1 joule = 1A at 1V for 1 second. Also applies to mechanical energy.Lead acid battery: Oldest rechargeable battery; used as starter battery wheeled mobility, UPS, etc.Lithium (Li): Soft, silver-white metal belonging to the alkali metal group; lightest and least dense metal in the element family; discovered by Johan August Arfwedson in 1817; metal is named after the Greek word “lithos” meaning “stone.”Lithium battery: Has lithium-metal anode; most are non-rechargeable.Lithium-ion battery: Rechargeable battery with cobalt, manganese, nickel and/or other metals as cathode and graphite anode.Lithium-ion polymer battery: Similar to Li ion with a solid polymer as electrolyte; addition of gelled material promotes conductivity.Lithium polymer battery: Also known as solid-state battery; uses solid polymer as electrolyte; heat induces conductivity.Load current: Current flow when applying an electrical load.Manchester coding, also known as phase coding, is used in 1-Wire battery communications to combine data and clock in a single-wire systemManganese (Mn): Cathode material of Li-ion. Also used in steelmaking.Matrix: Lookup table to compare and derive at characteristics, such as battery capacity.Max Error: Expected margin of error (%) of charge calibration on SMBus battery.Memory: Reversible capacity loss in nickel-based batteries.Microsecond (μs): One-millionth of a second (10-6).Milliampere-hour (mAh): Specifies battery capacity or rating; 1000mAh equals 1Ah.Millihertz: Unit of frequency. Example: 1 Hertz = 1 cycle/second; 1mHz = 1,000 seconds.Millisecond (ms): One-thousand of a second (10-3).Nano: Latin for dwarf. 1 nanometer (nm) is one-billionth (10-9) of a meter or a layer of 3–6 atoms.NCA: Nickel-cobalt-aluminum Li-ion; serves as cathode material.Negative delta V (NDV): Drop in battery voltage when sealed NiCd and NiMH reach full charge; used to detect full charge.Newton (N): Unit of force named after Isaac Newton; equal to accelerating 1kg a distance of 1 meter per second; (1N = 0.2248 pounds of force).Nickel-cadmium battery (NiCd): Rechargeable battery using cadmium as anode and nickel as cathode.Nickel-hydrogen battery (NiH): Rechargeable battery for satellites; pressure vessel contains the hydrogen.Nickel-iron battery (NiFe): Rechargeable battery developed by Thomas Edison in 1901.Used for mining; powered German V-1 flying bomb and the V-2 rockets during World War II.Nickel-metal-hydride battery (NiMH): Similar to NiCd; anode made of a hydride alloy that is less toxic than cadmium; 30 percent more capacity than NiCd but is less durable.Nickel-zinc battery (NiZn): Similar to NiCd; first developed in 1920; short life due to dendrite growth.Nit: Unit of brightness equal to one candela per square meter.NMC: Lithium-ion with nickel, manganese and cobalt as cathode material.Nominal voltage: Terminal voltage of batteries.Nyquist plots: Invented by Harry Nyquist (1889–1976) while working at Bell Laboratories; provides the frequency response of a linear system that displays both amplitude and phase angle on a single plot using frequency as parameter.Ohmic resistance: Electrical DC resistance with no capacitive and inductive reactance.OhmTest™: Battery resistance measurement based on IEC 61951 (Cadex trademark).Organic: Relating or belonging to carbon-based chemical compounds. Also relates to an organism, a living entity. Organic matter is the product of decay from a once living organismOvercharge: Exceeding charge acceptance. The battery heats up, produces gases and is subject to an evet.Overpack: Package can contain other non-dangerous or compatible dangerous good items. Limit is one package in accordance with Section II of PI 965. (Effective 1 April 2016).Parasitic load: Power consumption with the device turned off.Passivation layer: Resistive layer that forms on some batteries after prolonged storage. Applying a brief load breaks the layer and enables current flow.Peukert law: Calculates battery capacity on discharge rate; higher rates decrease capacity. Mainly used for lead acid batteries; a reading close to 1 indicates a battery with minimal loss; larger number reflect higher losses; named after Wilhelm Peukert (1897).Phosphate: Salt or phosphoric acid.Polymer: Electrical insulator that passes ions.Pouch cell: Packaged into a flexible, heat-sealable foil pouch similar to wrapping food products.Power: Voltage x current = power in watts (W). Also in horsepower (1hp = 746W).Power Cell: Battery cell designed for maximum current delivery. Energy density may be compromised.Power density: Also known as volumetric power density; reflects loading capability of a battery.Power factor: Ratio of real power versus apparent power. The unity power factor of 1 delivers 100% current to a load; a power factor of 0.50 reduces the contribution to 50%. A purely resistive load (heater elements) has a unity power factor of 1; a purely capacitive or inductive load has a power factor of 0.Primary battery: Non-rechargeable battery.Prismatic cell: A battery in which the positive and negative plates are stacked instead of rolled.Protection circuit: Electronic circuit in a battery pack maintains safety when exceeding design limits.Quick charger: Charges a battery in 3–6 hours.QuickSort™: Classifies battery state-of-health into good, low and poor (Cadex trademark).QuickTest™: Method to quick-test battery state-of-health (Cadex trademark).Ragone chart: Plots battery performance on specific energy versus specific powerRandles Model: Equivalent electrical circuit representing electrolyte resistance in a battery that is commonly used in electrochemical impedance spectroscopy (EIS).Rapid charge: Same as quick charge.Reactance: Inductive and capacitive resistance; frequency dependent.Recondition: Secondary discharge applied after end-of-discharge to drain the battery further; helps break down crystalline formation (memory) of nickel-based batteriesReformer: Device that extracts hydrogen from fossil and other fuels.Reserve Capacity: American way of measuring battery capacity by applying a fixed discharge current and measuring time in minutes. Europe uses the ampere-hour (Ah) method under DIN and IEC. DIN and IEC mark the battery in Ah at a typical discharge of 0.2C-rate (5h-rate).Residual capacity: Remaining battery capacity before charge.Resistance: Restriction to current flow; high resistance generates voltage drop and heat.Reverse load charge: Intersperses discharge pulses between charge pulses to promote the recombination of gases generated during fast charge; reduces memory.RSoC: Relative state-of-charge; available charge with capacity fade (also known as SoC).RSoH: Relative state-of-health; available storage capability when battery is broken in (also known as SoH)Runtime: The length of time a battery provides power with a charge.SAE J537: Test standard for 12V automotive starter batteries.
- RC: Apply a full charge (charge to 14.4–16V at 16°C–43°C (60°F–110°F)). After a 24h rest, apply a regulated 25A discharge to 10.50V (1.75V/cell). Readings are in minutes of discharge time known as “Reserve Capacity” (RC).
- CCA: Fully charge the battery and cool to -18°C (0°F) for 24 hours. While cold, apply a discharge current equal to the specified CCA reading. To pass, the voltage must stay above 7.2V (1.2V/cell) for 30 seconds.
Continue exploring: Use the Battery Fire, Acid & Hazard Safety guide for the related decision process, evidence, and practical guidance.
