Introduction to Battery Storage Systems
Expert-defined terms from the Advanced Certificate in Battery Storage for Renewable Energy course at London School of Planning and Management. Free to read, free to share, paired with a globally recognised certification pathway.
Introduction to Battery Storage Systems #
Introduction to Battery Storage Systems
Battery storage systems are an essential component of modern energy systems, ena… #
These systems store excess energy generated during periods of low demand for use during peak demand times or when renewable sources are not available. The Advanced Certificate in Battery Storage for Renewable Energy provides a comprehensive understanding of battery storage technologies, their operation, applications, and challenges. This glossary aims to explain key terms related to battery storage systems to enhance your knowledge and skills in this field.
A #
A
AC Coupling #
AC Coupling
Definition #
AC coupling is a method of connecting a battery storage system to an alternating current (AC) electrical system. In AC coupling, the battery is connected to the system through an inverter that converts the direct current (DC) output of the battery into AC to match the system's voltage and frequency.
Example #
A residential solar PV system with battery storage is AC coupled to the grid to enable energy storage and backup power capabilities.
Advanced Battery Management System (BMS) #
Advanced Battery Management System (BMS)
Definition #
An advanced battery management system (BMS) is a sophisticated control system that monitors and manages the performance, state of charge, temperature, and safety of battery cells or packs. It optimizes battery operation, protects against overcharging, and ensures long-term reliability.
Example #
An electric vehicle (EV) utilizes an advanced BMS to regulate the charging and discharging of its battery pack for optimal performance and longevity.
B #
B
Balancing #
Balancing
Definition #
Balancing refers to the process of ensuring that each cell in a battery pack has a similar state of charge to prevent overcharging or undercharging of individual cells. Balancing can be achieved through passive balancing (resistors) or active balancing (using electronics to redistribute charge).
Example #
During the charging process, the BMS actively balances the cells in a lithium-ion battery pack to maintain uniform charge levels.
Battery #
Battery
Definition #
A battery is a device that stores electrical energy in chemical form and converts it into electrical energy when needed. Batteries consist of one or more electrochemical cells that contain positive and negative electrodes, an electrolyte, and a separator.
Example #
A smartphone battery stores energy to power the device, enabling users to make calls, send messages, and access applications.
Battery Capacity #
Battery Capacity
Definition #
Battery capacity refers to the amount of energy that a battery can store and deliver under specific conditions. It is typically measured in ampere-hours (Ah) or watt-hours (Wh) and indicates the total charge that a battery can hold.
Example #
A 10 Ah battery can deliver a constant current of 1 A for 10 hours or 10 A for 1 hour before reaching its full capacity.
Battery Cycle Life #
Battery Cycle Life
Definition #
Battery cycle life is the number of charge-discharge cycles a battery can undergo before its capacity degrades to a specified level. It is a crucial factor in determining the longevity and reliability of a battery system.
Example #
A lithium-ion battery with a cycle life of 500 cycles can be charged and discharged 500 times before experiencing a significant capacity loss.
Battery Degradation #
Battery Degradation
Definition #
Battery degradation refers to the gradual loss of capacity and performance that occurs over time due to factors such as cycling, temperature, and aging. It affects the overall efficiency and lifespan of a battery system.
Example #
An electric vehicle battery may experience degradation over several years of use, resulting in reduced driving range and performance.
Battery Efficiency #
Battery Efficiency
Definition #
Battery efficiency is the ratio of the electrical energy output of a battery system to the input energy during charging and discharging cycles. It indicates how effectively the battery converts stored energy into usable electrical power.
Example #
A battery with 90% efficiency converts 90% of the input energy into usable output energy, with 10% lost as heat or other losses.
Battery Management System (BMS) #
Battery Management System (BMS)
Definition #
A battery management system (BMS) is an electronic control unit that monitors and manages the performance, safety, and longevity of a battery system. It regulates charging and discharging, balances cell voltages, and protects against overcharging and overheating.
Example #
A grid-connected energy storage system uses a BMS to optimize the operation of the battery bank and ensure safe and reliable performance.
Battery Monitoring System #
Battery Monitoring System
Definition #
A battery monitoring system (BMS) is a specialized system that continuously monitors the state of charge, voltage, temperature, and other parameters of individual battery cells or packs. It provides real-time data to optimize battery performance and prevent failures.
Example #
A large-scale solar farm employs a battery monitoring system to track the performance of multiple battery banks and optimize energy storage operations.
Battery Rack #
Battery Rack
Definition #
A battery rack is a structure or container that holds multiple battery modules or cells in a compact and organized arrangement. It provides mechanical support, cooling, and electrical connections for the batteries.
Example #
A utility-scale energy storage facility uses battery racks to house thousands of lithium-ion cells and manage the overall system configuration.
Battery State of Charge (SoC) #
Battery State of Charge (SoC)
Definition #
Battery state of charge (SoC) is the current level of charge in a battery relative to its full capacity, expressed as a percentage. It indicates how much energy is available for use and helps optimize charging and discharging operations.
Example #
A battery with 50% SoC has half of its total capacity remaining and can deliver 50% of its rated energy before requiring recharging.
Battery State of Health (SoH) #
Battery State of Health (SoH)
Definition #
Battery state of health (SoH) is a measure of the overall condition and performance of a battery system relative to its original specifications. It reflects the capacity, efficiency, and longevity of the battery over its operational life.
Example #
An energy storage system with a SoH of 80% has retained 80% of its original capacity and performance after several years of operation.
Battery System #
Battery System
Definition #
A battery system is a collection of interconnected battery modules or cells that work together to store and deliver electrical energy. It includes components such as racks, inverters, cooling systems, and monitoring devices to form a complete energy storage solution.
Example #
A residential battery system consists of multiple lithium-ion modules, a BMS, and an inverter to store and supply energy for household needs.
Battery Thermal Management #
Battery Thermal Management
Definition #
Battery thermal management is the process of controlling and regulating the temperature of battery cells or packs to optimize performance, safety, and longevity. It involves cooling or heating systems to maintain the batteries within an optimal temperature range.
Example #
An electric vehicle employs a liquid cooling system to dissipate heat from the battery pack and prevent overheating during fast charging or high-demand conditions.
Battery Voltage #
Battery Voltage
Definition #
Battery voltage is the electrical potential difference between the positive and negative terminals of a battery, indicating its output voltage. It determines the amount of electrical energy that can be delivered by the battery.
Example #
A 12-volt lead-acid battery provides a constant voltage of 12 volts to power automotive accessories and systems.
C #
C
Capacity Fade #
Capacity Fade
Definition #
Capacity fade is a gradual reduction in the storage capacity of a battery over time and cycling due to factors such as chemical reactions, electrode degradation, and aging. It leads to decreased energy storage and performance.
Example #
A lithium-ion battery may experience capacity fade after several years of use, resulting in reduced energy storage and shorter run times.
Cell Balancing #
Cell Balancing
Definition #
Cell balancing is the process of equalizing the charge levels of individual cells in a battery pack to prevent overcharging or undercharging. It ensures that all cells contribute evenly to the overall capacity and longevity of the battery.
Example #
A cell balancing circuit redistributes energy among the cells in a lithium-ion battery pack to maintain uniform charge levels and optimize performance.
C #
rating
Definition #
C-rating is a measure of the discharge or charge rate of a battery relative to its capacity. It indicates how quickly a battery can be charged or discharged without exceeding its maximum current rating.
Example #
A battery with a C-rating of 1C can be charged or discharged at a rate equal to its capacity in ampere-hours (Ah) per hour.
Current #
Current
Definition #
Current is the flow of electric charge through a conductor, measured in amperes (A). It indicates the rate at which electrical energy is transferred in a circuit and is essential for determining the power and efficiency of a battery system.
Example #
A battery charger delivers a current of 5 amperes to recharge a 12-volt battery with a total capacity of 60 ampere-hours.
Coulombic Efficiency #
Coulombic Efficiency
Definition #
Coulombic efficiency is the ratio of the actual charge delivered during discharge to the theoretical charge stored in a battery. It measures the efficiency of energy transfer during charging and discharging cycles.
Example #
A battery with a coulombic efficiency of 90% delivers 90% of the stored charge during discharge, with 10% lost as internal losses.
Cycle Life #
Cycle Life
Definition #
Cycle life is the number of charge-discharge cycles a battery can undergo before its capacity degrades to a specified level, typically 80% of its original capacity. It is a critical factor in determining the longevity and reliability of a battery system.
Example #
A lithium-ion battery with a cycle life of 500 cycles can be charged and discharged 500 times before experiencing a significant capacity loss.
D #
D
Depth of Discharge (DoD) #
Depth of Discharge (DoD)
Definition #
Depth of discharge (DoD) is the percentage of a battery's total capacity that has been discharged relative to its full charge capacity. It indicates how much energy has been extracted from the battery and affects its performance and longevity.
Example #
A battery with a DoD of 50% has been discharged halfway from its full charge capacity, leaving 50% of the energy remaining.
Direct Current (DC) #
Direct Current (DC)
Definition #
Direct current (DC) is an electrical current that flows in one direction, typically from the positive to the negative terminal of a battery or power source. DC is used in battery storage systems and many electronic devices.
Example #
Solar panels generate DC electricity, which is converted into AC by an inverter for use in residential or commercial buildings.
Discharge Rate #
Discharge Rate
Definition #
Discharge rate is the rate at which a battery releases stored energy during discharge, expressed in amperes (A) or C-ratings. It indicates how quickly the battery can deliver power to a load and affects its performance and efficiency.
Example #
A high-discharge-rate battery can deliver a large amount of current to power electric vehicles or high-demand applications.
Discharge Depth #
Discharge Depth
Definition #
Discharge depth is the extent to which a battery has been discharged relative to its total capacity, expressed as a percentage. It indicates how much energy has been consumed from the battery during a discharge cycle.
Example #
A battery with a discharge depth of 80% has used 80% of its total capacity during a discharge cycle, leaving 20% remaining.
DoD #
DoD
Definition #
Abbreviation for Depth of Discharge. See Depth of Discharge (DoD) for detailed definition and explanation.
E #
E
Electric Vehicle (EV) #
Electric Vehicle (EV)
Definition #
An electric vehicle (EV) is a vehicle that runs on electricity stored in batteries or fuel cells, rather than gasoline or diesel. EVs are environmentally friendly and promote energy efficiency and sustainability in transportation.
Example #
Tesla Model 3 is a popular electric vehicle that uses lithium-ion batteries to power its electric motors and deliver impressive performance.
Energy Density #
Energy Density
Definition #
Energy density is the amount of energy that can be stored in a battery per unit volume or weight, typically measured in watt-hours per liter (Wh/L) or watt-hours per kilogram (Wh/kg). It indicates the energy storage capacity and efficiency of a battery.
Example #
Lithium-ion batteries have a high energy density, allowing them to store more energy in a compact and lightweight form for portable devices and electric vehicles.
Energy Losses #
Energy Losses
Definition #
Energy losses refer to the amount of energy wasted or dissipated as heat, chemical reactions, or other inefficiencies during the charging and discharging of a battery. They reduce the overall efficiency and performance of the battery system.
Example #
Energy losses in a battery system can result from internal resistance, self-discharge, or conversion losses during energy transfer processes.
Energy Storage System (ESS) #
Energy Storage System (ESS)
Definition #
An energy storage system (ESS) is a collection of devices and components that store electrical energy for later use, such as batteries, capacitors, or flywheels. ESSs provide backup power, load shifting, and grid stabilization services.
Example #
A utility-scale ESS uses lithium-ion batteries and advanced control systems to store excess solar or wind energy and deliver it during peak demand periods.
Energy Management System (EMS) #
Energy Management System (EMS)
Definition #
An energy management system (EMS) is a software-based control system that optimizes the operation and performance of energy storage systems, renewable energy sources, and electrical loads. It regulates energy flow, storage, and distribution for efficiency and reliability.
Example #
An EMS coordinates the charging and discharging of battery storage systems in a microgrid to maximize self-consumption and minimize grid reliance.
Energy Storage #
Energy Storage
Definition #
Energy storage refers to the process of storing electrical energy generated from renewable or non-renewable sources for later use. It enables flexibility, reliability, and efficiency in power systems by balancing supply and demand.
Example #
A pumped hydro storage facility stores excess electricity by pumping water to a higher reservoir for later release to generate hydroelectric power.
Energy Storage Capacity #
Energy Storage Capacity
Definition #
Energy storage capacity is the total amount of electrical energy that can be stored in a battery system, expressed in watt-hours (Wh) or kilowatt-hours (kWh). It determines the duration and power output of the battery.
Example #
A 10 kWh energy storage system can store 10 kilowatt-hours of energy for use in residential backup power or peak shaving applications.
Energy Storage System (ESS) #
Energy Storage System (ESS)
Definition #
An energy storage system (ESS) is a collection of devices and components that store electrical energy for later use, such as batteries, capacitors, or flywheels. ESSs provide backup power, load shifting, and grid stabilization services.
Example #
A utility-scale ESS uses lithium-ion batteries and advanced control systems to store excess solar or wind energy and deliver it during peak demand periods.