Your comprehensive glossary to key terms and definitions
Ampere (A): Often referred to as Amp for short, it is a measure of how much electricity is flowing through a conductive material.
Ampere-Hour (Ah): A unit of measure for a battery’s electrical storage capacity obtained by multiplying the current in amperes by the time in hours of discharge. (Example: A battery that delivers 10 amperes for 8 hours delivers 10 amperes X 8 hours = 80 Amp-Hr of capacity.)
Ampere-Hour Throughput: The total sum of amp-hour capacity used during cycling over the life of the battery.
Anode: The negative electrode of a battery. It is the part of a battery that oxidizes and sends electrons to the cathode (the positive electrode) on discharge.
Battery Management System (BMS): An electronic system that manages and monitors the battery's performance, ensuring safe operation by protecting against abnormal conditions such as overcharge and over-discharge as well as thermal issues.
Battery Storage: The storage of excess energy in batteries for later use, often used in conjunction with renewable energy systems.
Casing and Cover: The container and lid of the battery containing all its parts such as the cells, battery management system, cabling, etc.
Capacity: The amount of charge a battery can hold and deliver to an external circuit, usually measured in ampere-hours (Ah). It indicates the battery's ability to power a device.
Carbon Footprint: The total amount of greenhouse gases (such as carbon dioxide) produced by human activities, including transportation, energy use, and industrial processes. Reducing carbon footprint is a key component of environment, social, and governance strategies for companies and investors.
Cathode: The positive electrode of a battery that is electrochemically reduced and receives electrons from the anode (the negative electrode) on discharge.
Cell: The individual electrochemical unit with a battery.
Cell Balancing: The process of altering individual cell voltage and state of charge through the distribution of charge current to produce uniform cell voltages. This process can help improve the battery's performance, safety, and longevity.
Charge (Q): A quantity of electrical capacity. The SI unit is the coulomb—equivalent to an ampere-second. However, the ampere-hour is the customary unit for batteries.
Charge/Charging: The process of applying an external electrical energy source to a battery during which time the electrical energy is converted to stored chemical energy through reactions at the anodes and cathodes of the battery.
Charge Current: The rate of energy (flow of electrons) imparted to a battery during charging.
Charge Cut-Off Voltage: The battery voltage at which the charging is terminated when reached under specified charging conditions.
Charge Cycle: A full discharge of the battery followed by a full recharge. One cycle represent a complete use of the battery's capacity.
Charge Rate: The speed at which a battery is charged, often expressed in terms of C-rate (i.e. 1C, 0.5C), where 1C represent the capacity of the battery being charged in one hour.
Circuit (Parallel): A circuit that provides more than one path for the flow of current. A parallel arrangement of batteries (usually of like voltages and capacities) has all positive terminals connected to a conductor and all negative terminals connected to another conductor. A parallel circuit adds the capacities of all batteries without increasing battery voltage.
Circuit (Series): A circuit that has only one path for the flow of current. Batteries arranged in series are connected with negative of the first to positive of the second, negative of the second to positive of the third, etc. A series circuit adds the voltages of each battery without increasing capacity.
Cold Cranking Performance Rating (CCA): The rating set by the battery manufacturer indicating the discharge load in amperes which a new fully charged and conditioned battery at -18 oC (0 oF) can continuously deliver for 30 seconds and maintain a terminal voltage equal to or higher than 1.20 volts per cell (7.2 V for a 12 V battery) subject to statistical analysis. European standards (EN) also have a CCA rating defined somewhat differently.
Corrosion: The electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties. The positive lead grids in a battery gradually corrode in service often leading to battery failure. Battery terminals are also subject to corrosion if they are not properly maintained.
Current (I): The rate of flow of electricity, or the movement of electrons, along a conductor (comparable to the flow of a stream of water). The unit of measure for current is the ampere.
Current (Alternating) (AC): An electrical current that periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current. A battery does not deliver alternating current.
Current (Direct) (DC): An electrical current flowing in an electrical circuit in one direction only. A secondary battery delivers direct current and must be recharged with direct current in the opposite direction of the discharge.
Cycle Life: The count of total cycles for a given standard test profile, measured until the battery is unable to meet minimum test criteria (e.g. discharge voltage or current) Different standardized tests have different sized cycles and testing parameters depending upon the type of battery. Results are not directly comparable.
Cylindrical Cell: A battery cell construction where the positive and negative electrodes and separators are jelly-rolled into a cylindrical shape as opposed to a layered, flat electrode orientation (known as prismatic) and inserted into a tube-shaped housing.
Deep Discharge: A discharge when a relatively large portion of the battery capacity, for a given rate of discharge, is removed. Typically the voltage cutoff is 1.75 VPC to avoid cell reversal. Deep cycle batteries are designed to be repeatedly deep discharged without significant damage.
Depth of Discharge (DoD): The percentage of the battery's total capacity that has been used.
Discharging: When a battery is delivering current, it is said to be discharging.
Discharge Rate: The speed at which a battery releases its stored energy, often expressed in terms of C-rate (i.e. 1C, 0.5C), where 1C represents the capacity of the battery being discharged in one hour.
Eco-Friendly: A term used to describe products, practices, and technologies that have a minimal impact on the environment and promote sustainability.
Electrode: The combination of active material that electrochemically stores and releases energy and a conducting substrate that supports or contains the material and allows useful electrical energy to flow to an external circuit.
Electrolyte: An ionic (non-metallic) conductor of electricity (typically liquid) placed between the positive and negative electrodes of a battery. Ion movement enables internal current flow. In a lead-acid battery, the electrolyte is sulfuric acid diluted with water that also participates in the chemical reactions.
Energy Efficiency: The use of less energy to perform the same functions, reducing the amount of energy required to produce goods and services and minimizing greenhouse gas emissions.
Equalization Charge: The process of ensuring that the cells and electrodes within a battery are all at full charge and that the electrolyte is uniform and free of stratification. This is normally done by charging the battery under controlled conditions (charge current, time and upper voltage limits).
Float Charge: A constant voltage charging method intended for extended periods of time in which the voltage set point is lowered and optimized for low water loss and reduced grid corrosion while maintaining the battery at a full state of charge.
Ground: The reference zero potential of a circuit. In automotive use, the result of attaching one battery cable to the body or frame of a vehicle that is used as a path for completing a circuit in lieu of a direct wire from a component. Today, over 99% of automotive and LTV applications, use the negative terminal of the battery as the vehicle ground.
Hazardous Waste: Refers to waste that is potentially dangerous or harmful to human health or the environment, such as chemicals or radioactive materials.
Intercell Connectors: Hardware or components that connect adjoining battery cells in series, the positive of one cell to the negative of the next.
Internal Resistance: The opposition to the flow of electric current within the battery. Lower internal resistance generally results in higher battery efficient.
Lithium Iron Phosphate (LiFePO4): A type of lithium battery chemistry known for its stability, safety, power density, and long cycle life, often used in applications requiring high safety.
Maintenance Free Battery: A battery that normally requires no service watering during its lifetime of use.
Memory Effect: Certain types of batteries, such as nickel-cadmium and nickel-metal hydride, can develop a memory effect when only partially discharged before recharging. This “memory” reduces the capacity of subsequent charges and thus future battery performance. The effect can also be caused by poorly designed chargers.
Negative: Designating, or pertaining to, a point of electrical potential. The negative battery terminal is the point from which electrons flow during discharge.
Net Zero: The result of lowering greenhouse gas emissions as close as possible to zero and balancing remaining emissions with removals.
Ohm: A unit for measuring electrical resistance or impedance within an electrical circuit or battery.
Ohm's Law: Expresses the relationship between volts (V) and current (I) in an electrical circuit with resistance (R). It can be expressed as follows: Volts (V) = Amperes (I) x Ohms (R).
Open Circuit Voltage: The voltage of a battery measured in the absence of charge or discharge current.
Overcharge: Charging a battery above its maximum voltage threshold. This can result in overheating, reduced lifespan, or battery damage.
Over-Discharge: Discharging a battery below its minimum voltage threshold. This can result in reduced lifespan or battery damage.
Positive: Designating, or pertaining to, a kind of electrical potential; opposite of negative. A point or terminal on a battery having the higher relative electrical potential. The positive battery terminal is the point to which electrons flow during discharge.
Prismatic Cell: A cell constructed with flat, rectilinear plates housed in a container with flat interior walls.
Rechargeable Battery: A battery that can have its capacity restored by a charging current.
Recycling: The process of collecting and processing waste materials, ideally to make new products. Usually requires treatment, and energy consuming procedure.
Regulatory Compliance: A company’s adherence to applicable laws and regulations in its operations. Regulatory compliance is important as it helps ensure that a company is operating in a responsible and legal manner and that its activities align with stakeholders’ interests.
Renewable Energy: Energy sources that are replenished naturally, such as wind, solar, and hydropower. Renewable energy is seen as an important ESG issue because it reduces dependence on finite fossil fuels and helps mitigate climate change.
Resistance: The opposition to the free flow of direct current in a circuit or battery. Resistance (measured in units of ohms or milliohms) in batteries is a measure of the rapid change in voltage with respect to the rapid change in current.
Self-Discharge Rate: The rate at which a battery loses its charge when not in use.
Service Life: The normal operating period of time for a battery in an application until it no longer satisfies the minimum application requirements.
Short Circuit: An abnormal conditions where the anode and cathode of the battery are connected together with a zero/low resistance conductive material. Never short circuit the battery terminals with any conductive materials.
Solar: Refers to energy derived from the sun, typically using photovoltaic panels.
State of Charge (SoC): The percentage of the battery's total capacity that is still available to use.
Terminals: The electrical structures on the battery to which the external circuit is connected. Typically, batteries have either top-terminals (posts) or side-terminals. Some batteries have both types of terminals (dual-terminal).
Thermal Runaway: An uncontrolled increase in battery internal temperature during a voltage-controlled charging process where the current rate increases as the battery temperature continues to rise causing the electrolyte to boil away.
Torque: The amount of force required to rotate an object around a point.
Trickle Charge: A technique used to describe maintaining the charge level of a battery by charging with a small current either through float charging (which is constant voltage) or a small constant current charge.
Volt: The unit of measure for electrical potential.
Voltage: The electrical potential difference between the anode and cathode of a battery.
Voltmeter: An electronic device used to measure voltage, normally in a digital format.
Voltage Drop: The net difference in the electrical potential (voltage) when measured across a resistance or impedance (ohms) with applied current. See Ohm’s Law.
Waste Management: The process of managing water resources in a sustainable manner, including ensuring access to clean drinking water, reducing water waste, and protecting water ecosystems.
Watt-Hour (Wh): A unit of energy equivalent to one watt of power used for one hour. It is used to quantify battery capacity in terms of energy.