Explanations of technical battery terms.

A

A: Ampere.

AC: Alternating current.

Acid: A chemical, usually a liquid, compound in a battery and used as conductive agent.

AC-to-DC: Alternating current to direct current converter.Similar to AC-DC orAC/DC.

Aging: The battery has gone through a complete charging and discharging process. This process fully activates the battery's active substances.

AGM: Absorbent Glass Mat.It is a lead acid battery.

AGV: Automatic Guided Vehicle.

Ah:  Ampere-hour; It represents the capacity of the battery. Example: Drawing a current of two amperes (2A) from a battery for one hour (1h) equates in two ampere-hour (2Ah).

Anode: Electrode on which oxidation occurs; releases electrons on discharge. 

ASoC: Absolute state-of-charge; Initial capacity of a new battery under standard charge and discharge conditions.

ASoH: Absolute state-of-health; Initial parameters of various aspects of a new battery.

B

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  & parallel; composed of the anode (negative electrode), cathode (positive electrode), separator and electrolyte.

Battery Charger: A power converter that provides the correct voltage and charging mode for a battery.

Battery cycle: The battery undergoes a complete charge and discharge process many times, which is called the battery cycle.

Battery Directive 2006/66/EC: European legislation on waste batteries to protect the environment.

BCI: Battery Council International.

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/SOH/State,communicate through  different software,like CAN、RS485、Bluetooth、Smbus、TCP/IP etc..

Bluetooth: Low-power radio communications up to 10 meters (30 feet). 

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. It can not be recharged.

C

Can Bus: Controller Area Net-work Bus, It is a serial bus system that connects field equipment (sensors, actuators, controllers, etc.) and faces broadcast in the manufacturing plant. It was first developed by General Motors (GM) for the automotive industry, and then increasingly appears in the manufacturing automation industry.  

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.

Capacity: Electrical energy of a battery in ampere-hours (Ah). The stored energy is recorded by observing the elapsed time while discharging at a standard current to the end-of-discharge voltage. The capacity is a key parameter of a battery.

Capacity offset: Capacity correction when discharging a battery at a high C rate/temperature exceeds the specified.

Cathode: Electrode in an electrochemical cell in which reduction takes place by absorbing electrons. During discharge, the cathode is positive; reverse on charge.

Cell mismatch: The cells in a battery pack have differences in voltage, capacity, internal resistance, etc.  

Cell reversal: After severe overdischarge of the battery, positive and negative polarity reversals are caused.  

CC-CV: Constant current -constant voltage (charge method for lead acid, Li-ion).

CCV: Closed circuit voltage (The voltage of a battery when it is charged or discharged).

CE: CONFORMITE EUROPEENNE, The "CE" mark is a safety certification mark that is seen as a passport for manufacturers to open and enter the European market.  

Charge: Recharge a cell or battery under suitable voltage.

Chemical battery: A device that converts chemical energy into electrical energy.  The main part includes electrolyte solution and positive and negative electrodes of immersion solution. 

CID: Circuit interrupt device, function like a fuse.

CL: Current limiting (as in charging or discharging a battery).

Cobalt (Co): Hard, lustrous, gray metal; used in batteries, magnets, and high-strength alloys.

Coulomb: Unit of electric charge, symbol C. If a wire carries a steady current of 1 ampere, the amount of electricity passing through the cross section of the wire in 1 second is 1 coulomb.   

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 10C, the battery is charged or discharged at ten times its capacity.

Current-limiting charger: Keeps current constant and allows voltage to fluctuate(NiCd, NiMH chargers).

Cycle:  Charging, discharging, and charging a battery. A standard cycle is a complete process of recharging and discharging of the battery.  

Cycle life: How many standard charge and discharge cycles can a battery complete. 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.

D

DC: Direct current; Battery delivers a DC current.

DCA: Dynamic charge acceptance.

DC-to-DC: Converts DC to a higher or lower voltage potential.Similar to DC-DC orDC/DC.

Delta temperature over delta time (dT/dt): Measure temperature changes in relation to time; used for full charge detection of nickel-based battery.

DIN, IEC: Deutsches Institut für Normung (German Institute for Standardization) .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. used for lead-acid battery.

Discharge: The battery is giving off energy.

DoD: Depth of discharge; 100% is full discharge.

DoE: Department of Energy (US).

Double-layer capacitor: Also called supercapacitors or ultracapacitors ,electrostatic storage device utilizing the electrical double layer effect that is formed near the surface of the carbon electrode.

Driving range: EVs display the allowable driving rang range rather than capacity, capacity is not exactly proportional to driving mileage.

E

EBM: Electronic battery monitor.

EIS:Electrochemical Impedance Spectroscopy.

Electrode: Conductor or plate in a cell in which an electrochemical reaction occurs.

Electrolyte: Non-metallic conductor (usually liquid) placed between the positive and negative terminals of a battery. The movement of ion produces electric current.

EMC: Electro Magnetic Compatibility.

EMI: Electro-Magnetic Interference.

Energy: Work measures over time. Wh is a very common unit in battery energy calculations.Multiplying voltage x current x time = Watt-hours (Wh).

Energy Cell: Battery/cell designed for maximum capacity. Its C-rate performance will go down.

Energy density: Also known as volumetric energy density; specifies the amount of energy a cell can hold in volume (Wh/l). It is one of the criteria to judge the performance of different types of batteries.  

Energy Star: Organization promoting energy efficiency.

ESS: Energy storage systems.

EV: Electric vehicle.

Exercise: Refers to a battery that has gone through one or more complete cycles. It is usually used for accurate capacity calculation of lithium-ion batteries and to prevent memory effect of Ni-MH and Ni-CR batteries.  

F

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: The battery is charged at a current above 0.5C and the charging time is 2h-0.5h.  Some high-power batteries can accept 5C or even 10C charging current and can be charged to 80% capacity in 10 minutes.  

Float charge: In the case that the charging voltage is always present

,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. 

Frequency: Number of events in a given time. Indicates how often the AC voltage changes from positive to negative per second, it represents the number of battery uses in a given period of time.

Fuel cell: Also known as FC.Device converts oxygen and hydrogen into electricity and water. 

Fuel gauge: It is generally calculated by Coulomb calculation method and finally appears in the form of SOC.

Full Charge: Battery/cell charged to 100% capacity at the charging voltage specified in the specification.

Full Discharge: Battery/cell discharge to end-of-discharge voltage, capacity is 0%.

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.

G

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); It is one of the criteria to judge the performance of different types of batteries.

H

H: Hour (time).

Halon: Agent to suppress fire. Used also for Li-ion fires.

Hertz (Hz): Unit of frequency; 1Hz constitutes one full cycle per second.

HEV: Hybrid electric vehicle.

Hp: Horsepower (power) 1hp = 745.7 watts.

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; It is generally used to 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.

I

I: Current (electrical).

I2C: Inter-Integrated Circuit,it is a multi-master, multi-slave, single-ended, serial computer bus invented.

IATA: International Air Transport Association.

IEC 60079: Intrinsically safe standards to prevent explosion in areas of flammable gas and dust.

IEC: International Electrochemical Commission.

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: Obstructs the flow of electricity; measured in ohms (R).

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.

IPF: Interfacial protective film.

IPP: IEC aircraft battery rating (0.3/15s power discharge).

IPR: Aircraft battery rating according to IEC (15s power discharge).

Ion: Atom or molecule with unequal number of electrons and protons; provides a positive or negative electrical charge.

J

Joule (J): Energy measurement: 1 joule = 1A at 1V for 1 second. Also applies to mechanical energy.

JCESR: Joint Center for Energy Storage Research.

K

kW: Kilowatt (electrical power); 1kWh = 3.6MJ; 1MJ = 860kcal = 238cal/s.

kWh: Kilowatt-hour (electrical energy).

L

Lead acid battery: Oldest rechargeable battery; used as starter battery wheeled mobility, UPS, automobile,etc.

LFP: Lithium iron phosphate (also LiFePO4, secondary battery).

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”.

LiCoO2: Lithium ion cobalt oxide (also LCO, rechargeable battery).

LiFePO4: Lithium iron phosphate oxide (also LFP, secondary battery).

LiFeS2: Lithium iron disulfide (primary battery).

Li-ion: Lithium-ion battery (short form).

Li-M: Lithium manganese dioxide (also LiMnO2, primary battery).

LiMn2O4: Lithium ion manganese oxide (also LMO, secondary battery, spinel structure).

LiMnO2: Lithium manganese dioxide (primary battery, different from secondary LiMn2O4)

LiNiCoAlO2: Lithium ion nickel cobalt aluminum oxide (also NCA, secondary battery).

LiNiMnCoO2: Lithium ion nickel manganese cobalt oxide (also NMC, secondary battery).

Li2TiO3: Lithium titanate oxide (also LTO, secondary battery).

LiSO2: Lithium sulfur dioxide (primary battery).

LiSOCI2: Lithium thionyl chloride (also LTC, primary battery).

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.

M

Manganese (Mn): Cathode material of Li-ion. Also used in steelmaking.

Max Error: Expected margin of error (%) of charge calibration on SMBus battery.

Memory  effect: It refers to the appearance that loss of capacity caused by incomplete discharge or incomplete charge of a battery.

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).

MPPT : Maximum power point tracking.

MW: Megawatt (power),1MW=1000KW.

N

Nano:  1 nanometer (nm) is one-billionth (10-9) of a meter or a layer of 3–6 atoms.

NCA:Lithium-ion battery with nickel, cobalt, aluminum cathode (also LiNiCoAlO2).

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-iron battery (NiFe): Rechargeable battery developed by Thomas Edison in 1901.Used for mining.

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.

NMC: Lithium-ion with nickel, manganese, cobalt cathode (also LiNiMnCoO2).

Nominal voltage: Terminal voltage of batteries, in the absence of any load.

NTC: Negative temperature coefficient.

O

OCV: Open circuit voltage.

OVP:Over Voltage Protect. When the battery voltage is higher than the set value,PCM/BMS will action to cut off charge circuit.

OCP: Over Current Protect. When the discharging current is higher than the set value,PCM/BMS will action to cut off discharge circuit.

OTP: Over Temperature Protect. When the temperature of battery cell is higher than the set value,PCM/BMS will action to cut off charge/discharge circuit.

Ohmic resistance: Electrical DC resistance with no capacitive and inductive reactance.

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 organism.

Overcharge: Exceeding charge acceptance.

Overdischarge: Exceeding discharge acceptance.

P

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.

PCM: protection circuit management.

Phosphate: Salt or phosphoric acid.

Polymer: Electrical insulator that passes ions.

Pouch cell: Packaged into a flexible, heat-sealable foil pouch.

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(pf): 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.

PHEV: Plug-in hybrid electric vehicle.

Primary battery: Non-rechargeable battery.

Prismatic cell: A battery that looks like a square object.

Protection circuit: Electronic circuit in a battery pack maintains safety when exceeding design limits.

PTC: Positive temperature coefficient.

Q

QA: Quality assurance.

Quick charger: Charges a battery in 3–6 hours.

R

R&D: Research and development.

Rapid charge: Same as quick charge.

Recondition: Secondary discharge applied after end-of-discharge to drain the battery further; helps break down crystalline formation (memory) of nickel-based batteries.

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. This is suitable for charging lead-acid batteries.

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.

S

S: Second (time).

SAE: Society of Automotive Engineers, founded early in 1900 by US auto manufacturers.

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.

SAE J1634: Test standard for electric vehicle; energy consumption, range.

SAE J1772: North American standard for electrical connectors for electric vehicles.

SBS: Smart Battery System.

Secondary battery: Rechargeable battery.

Self-discharge: Capacity loss due to internal leakage.

Separator: Isolates cathode and anode in a battery; acts as catalyst to promote ion movement from cathode to anode on charge and in reverse on discharge.

Single-wire Bus: Simplified  with one wire providing digital communications.

SLA: Sealed lead acid (battery).

SLI: Starter-light-ignition (battery), also known as starter battery.

Slow charge: Overnight charge lasting 10–16 hours at a charge current of 0.1C.

Smart battery: Also known as an intelligent battery; communicates with device, charger and user.

SMBus: System Management Bus is a two-wire interface based on I2C; communicates with the battery and device by accepting control parameters and providing battery status, such as state-of-charge, manufacturer information, cycle count and error messages.

Solid electrolyte interface (SEI): A film composed of lithium oxide and lithium carbonate forms on the surface of the Li-ion anode. The SEI layer grows with cycling and can form a barrier to obstruct ion flow.

Specific energy: Also known as gravimetric energy density; indicates the amount of energy a cell contains in weight (Wh/kg); relates to battery capacity.

Specific power: Also known as gravimetric power density; reflects the loading capability or the amount of current the battery can deliver; readings in W/kg.

Spinel: Hard glassy mineral consisting of an oxide of magnesium and aluminum that forms a three-dimensional chemical structure. Manganese-based Li ion has such a spinel structure.

State-of-charge (SoC): Indicates charge level of a battery; normally measured in percent. SoC has no relationship with capacity.

State-of-function (SoF): Reflects battery readiness that verifies capacity, current delivery, voltage, SoC, self-discharge and more; measured in %. (Capacity, current delivery and SoC are most basic.)

State-of-health (SoH): Reflects battery performance that verifies capacity, current delivery, voltage and self-discharge; measured in %. SoH excludes SoC.

Sulfation: Formation of lead sulfate crystal in a lead acid battery that inhibits current flow; storage at low state-of-charge causes this.

Supercapacitor: Electrochemical capacitor also known as an ultracapacitor or double-layer capacitor; Has high cycle life; offers good cold temperature performances.

T

Thermal runaway: Uncontrolled disintegration of a battery from the inside out; can be caused by cell defect, overcharging, excess heat and other abusive conditions.

Thermistor: Electrical resistor that changes resistance with temperature.

Titanate: Substance used for anode material of some lithium-based batteries.

Trickle charge: Also known as maintenance charge, compensates self-discharge of a battery.

U

UL: United Laboratories (product safety testing and certification).

UL 1642: Safety acceptance test for lithium-based batteries by Underwriters Laboratories. Other agencies are IEC 62133, IEEE 1625, IEEE 1725, BAJ (Japan), UN. In 2010, UL 1642 transitioned to IEC 62133, made fully effective on 1 May 2012.

UL 2054: Safety acceptance test for lithium-ion battery pack.

UN 38.3: Safety norms for shipping battery products.

UPS: Uninterruptible power supply.

UTP: Under Temperature Protect. When the temperature of battery cell is lower than the set value,PCM/BMS will action to cut off charge/discharge circuit.

UVP:Under Voltage Protect. When the battery voltage is lower than the set value,PCM/BMS will action to cut off discharge circuit.

V

VA: Volt-ampere (similar to watt with true current flow in a reactive load).

VAC: Voltage with alternating current (grid).

Valve-regulated lead acid (VRLA): Maintenance-free lead acid battery recombines oxygen (positive plate) with hydrogen (negative plate) on charge; valve regulates pressure by release of excess gases. Repeated venting will lead to dry out.

Voltage (V): Electric energy potential per unit charge. 

Voltage delay: During prolonged storage, some battery systems develop a passivation layer. This results in a momentarily lower voltage until the film is dissipated through discharge.

Voltage limit(VL): Battery thresholds on charge and discharge.

Voltage-limiting charger: Current is allowed to fluctuate in saturation mode while the voltage is capped (lead acid and Li ion charging).

Volumetric energy density: Also known as energy density; specifies energy storage in volume (Wh/l).

W

Watt (W):Unit of power; voltage x current = watts.

Watt-hour (Wh): Unit of electrical energy equivalent to a power consumption of one watt for one hour.  Watts x h = Wh ,multiplying a battery voltage (V) by the rated capacity (Ah) gives the battery energy in Wh. Example: 12V x 10 Ah = 120Wh.

W/kg: Watt per kilogram (measurement of specific power).

Wh/kg: Watt-hour per kilogram (measurement of specific energy).

Wh/km: Watt-hour per kilometer.

Wh/l: Watt-hour per litter (measured in energy density).

Wi-Fi: Wireless Internet connections; based on 2.4GHz 802.11b standard.

WPC: Wireless Power Consortium, standard for wireless charging.

Z

Zapping: Applying a momentary current pulse to a battery to evaporate a short.

Zinc-air: Generates electrical energy by an oxidation process of zinc and oxygen. Most zinc-air batteries are non-rechargeable, provide high specific energy but have poor load capabilities.