Introduction to Battery Pack Design and Assembly 240

adhesives

A substance used to join two or more materials without welding or mechanical fasteners. Adhesives include glues, resins, and epoxies.

advanced manufacturing

The use of innovative technology and processes to improve the manufacturing of products. Advanced manufacturing technologies include additive manufacturing, sophisticated robotics, and increased connectivity.

aluminum

A highly conductive, lightweight, silvery metal. Aluminum is often used for busbars.

anode

An electrode with a negative charge. In a battery, the anode sends current to the cathode.

arrayed

Arranged in a particular way. Battery modules are usually arrayed in columns and rows, called an array, to ensure the pack is neat, serviceable, and functions correctly.

automation

The use of self-regulated equipment, processes, or systems that meet manufacturing requirements with limited human intervention. Automation can be achieved with robots or computer numerical control (CNC) machines.

battery management system

BMS. A computer that monitors, regulates, and coordinates the operations of a battery pack. The battery management system in an EV may be either centralized, distributed, or modular.

battery pack

A group of battery cells connected to produce large amounts of electrical energy. Battery packs may also include components such as sensors and battery management systems.

BMS

Battery management system. A computer that monitors, regulates, and coordinates the operations of a battery pack. The BMS in an EV may be either centralized, distributed, or modular.

busbars

Strips of copper or aluminum that create the main electrical connections between cells, modules, or other rechargeable battery components. Busbars are usually rigid, but flexible busbars are available.

cans

A protective, conductive metal cover on battery cells. Cans are typically cylindrical or prismatic and help prevent undesired swelling, bending, and damage to cells.

capacity

The amount of energy a battery can store. Capacity is determined by the materials and size of the battery.

cathode

An electrode with a positive charge. In a battery, the cathode receives current from the anode.

cell chemistry

The chemical composition that influences a battery's energy density, efficiency, cost, and lifecycle. Rechargeable batteries most commonly have lithium-ion, nickel-metal hydride, and lead-acid cell chemistries.

cell geometry

The shape, dimensions, or design of a battery cell. Cell geometry can influence battery pack size, life, and placement, as well as heat distribution.

cell-module-pack

CMP. A design and assembly process in which a battery is built up from the smallest unit to the outer protective housing. Cell-module-pack batteries start with cells that are assembled into modules, which are placed into packs.

cells

A single unit of a battery. Cells contain a cathode, an anode, and an electrolyte solution.

cell-to-body

CTB or C2B. A design and assembly process in which battery cells are installed directly into the chassis of an EV. Cell-to-body batteries, or cell-to-chassis (CTC or C2C) batteries, are structural batteries and often serve a secondary function, such as doubling as the floor of an EV.

cell-to-chassis

CTC or C2C. A design and assembly process in which battery cells are installed directly into the chassis of an EV. Cell-to-chassis batteries, or cell-to-body (CTB or C2B) batteries, are structural batteries and often serve a secondary function, such as doubling as the floor of an EV.

cell-to-pack

CTP or C2P. A design and assembly process in which battery cells are placed directly in a pack. Cell-to-pack batteries eliminate the assembly steps, cost, and extra materials required to wire cells into modules.

charge

To receive and store electrical energy. Rechargeable batteries must charge reliably and safely in a variety of environmental and use conditions.

chassis

The frame of a machine. The chassis of a car is made of metal and supports the body.

circuit

A completely enclosed path for electrical current. Electrical circuits usually include a source, path, load, and control.

clean rooms

A controlled environment that has a low level of environmental pollutants such as dust, airborne microbes, aerosol particles, and chemical vapors. Clean rooms are often required throughout manufacturing for sensitive electronics like those used in rechargeable batteries.

CMP

Cell-module-pack. A design and assembly process in which a battery is built up from the smallest unit to the outer protective housing. CMP batteries start with cells that are assembled into modules, which are placed into packs.

conductive

Having the ability to act as a path for the movement of electricity. Conductive materials include semiconductors and metals like aluminum and copper.

contactors

A type of switch that is designed to handle heavy and fluctuating current loads. Contactors use an electromagnetic coil to provide safe connection and disconnection between EV motors and high-voltage battery packs.

contamination

The presence of damaging foreign or atmospheric materials such as dirt, moisture, skin cells, fabric particles, or oil. Contamination can damage sensitive electronics and compromise battery quality.

cooling mechanisms

A device that removes heat from an electrical system in order to regulate temperature. Cooling mechanisms in EV battery packs work by circulating either air or liquid coolant.

copper

A ductile, reddish metal that is thermally and electrically conductive. Copper is often used for busbars.

CTB

Cell-to-body or C2B. A design and assembly process in which battery cells are installed directly into the chassis of an EV. CTB batteries, or cell-to-chassis (CTC or C2C) batteries, are structural batteries and often serve a secondary function, such as doubling as the floor of an EV.

CTP

Cell-to-pack or C2P. A design and assembly process in which battery cells are placed directly in a pack. CTP batteries eliminate the assembly steps, cost, and extra materials required to wire cells into modules.

current

The flow of electricity. Current strength is called amperage and is measured in amperes (A).

cylindrical cells

A type of rechargeable battery cell enclosed in a rigid, tube-shaped can. Cylindrical cells provide more power than prismatic cells and are common in high-performance applications.

dimensions

A measurement of space, especially length, width, and height. Dimensions of a part are detailed in a blueprint or computer aided design (CAD) model.

electric shock

The flow of electricity through the body. Severe electric shock can be fatal.

electric vehicles

EVs. A vehicle that is propelled by an electric motor that draws its power from a battery. Electric vehicles, including hybrid electric vehicles, require high energy, lightweight, rechargeable batteries.

energy

The ability or capacity to do work. Energy is stored as chemical energy in rechargeable batteries.

energy density

The ratio of a battery's energy-delivery capability to its mass or volume. Energy density is often measured in kilowatt-hours per liter (kWh/L) or kilowatt-hours per kilogram (kWh/kg).

environmental conditions

The characteristics of a device's surroundings that determine how it reacts, performs, or wears. Environmental factors that affect most rechargeable batteries include dust, vibration, moisture, and temperature, especially when operating EVs.

EV

Electric vehicle. A vehicle that is propelled by an electric motor that draws its power from a battery. EVs, including hybrid EVs, require high energy, lightweight, rechargeable batteries.

features

A defining characteristic on a component or part. Features include corners, edges, holes, and grooves.

foil

An exceedingly thin sheet of metal. Foils are usually made with metals that are easily drawn out, such as aluminum, copper, or tin.

fuel efficiency

A measure of the distance an EV is expected to travel on 33.7 kilowatt-hours of battery capacity, which is roughly equivalent to the energy contained in one gallon of gasoline. Fuel efficiency in EVs is measured in miles per gallon of gasoline-equivalent (MPGe), and EVs with higher fuel efficiency can travel further per 33.7 kilowatt-hours.

fuses

A safety device that opens a circuit when it detects excess current. Fuses often have a component that melts to open the circuit.

housing

A protective cover designed to contain the cells, modules, and all the circuitry and sensors required for a rechargeable battery to function. A battery housing can be rigid metal or plastic.

kilowatt-hour

kWh. A unit used to measure electrical energy usage or delivery over time. One kilowatt-hour indicates that a battery can supply 1,000 watts of electricity for one hour.

lasers

An intense beam of coherent, collimated, monochromatic light that can be precisely aimed and controlled. Lasers can be used for cutting, welding, surface cleaning, and other manufacturing processes.

loads

A component in a circuit that converts electricity into light, heat, or mechanical motion. Loads include electric motors.

mass

A measure of the amount of matter in an object. A battery's mass in kilograms (kg) can be used to determine its energy density.

mechanical fasteners

A device that holds two or more objects together by force. Mechanical fasteners include screws and bolts.

modeling

The process of creating a three-dimensional (3D) representation of a surface or object by manipulating geometric shapes in a simulated 3D space. Modeling has a variety of applications, such as allowing engineers to test a product design under specific conditions and make changes to the design.

modules

A unit that contains several battery cells connected in either series or parallel. Modules in EV battery packs also contain fuses, sensors, and cooling mechanisms.

motor

A machine that converts one form of energy into another. A motor often transforms electrical energy into mechanical energy.

overcurrent

An excess of current flowing through a circuit. Overcurrent can overload and damage circuit components or lead to fire or electric shock.

parallel

Connected across components. In parallel, the positive terminals of cells are connected to other positive terminals, then the negative terminals are connected to other negative terminals, to increase a battery pack's capacity.

parallel-series

Connected in parallel, then in series. In parallel-series battery packs, individual cells are connected in parallel, then groups of parallel cells are connected in series to increase a battery pack's voltage and capacity.

plasma

A state of matter created by energizing a gas. Plasma is the fourth state of matter characterized by its high temperature and electrical conductivity.

polar

Having two oppositely charged poles, one positive and one negative. Battery cells, modules, and packs are all polar devices.

pouch cells

A type of rechargeable battery cell enclosed in a flexible, multi-layer foil wrapper. Pouch cells are flexible, lightweight, and most common in portable devices like laptops and smartphones.

power

The rate at which a device converts electrical energy into another form of energy, such as heat, movement, or light. Power is measured in watts (W).

power grids

An interconnected network for electricity delivery and storage. Power grids that use rechargeable batteries as storage devices are increasingly common.

precision

The ability of a process to repeat the same accurate measurement or production task over time. Automation and robotics increase precision in rechargeable battery manufacturing.

prismatic cells

A type of rechargeable battery cell enclosed in a rigid, rectangular can. Prismatic cells are easy to stack and store more energy per cell than cylindrical cells.

range

The maximum distance an electric vehicle can travel on a fully charged battery. Rechargeable batteries must provide a reasonable, consistent range for their price and energy density and in a variety of environmental conditions.

rechargeable batteries

A battery that can be recharged. Rechargeable batteries, or secondary cell batteries, are charged by running electrical current back through them to restore their chemical energy.

recyclability

The ability to be reused or repurposed at the end of its useful lifecycle to minimize waste, pollution, and resource use. Recyclability influences electric battery design choices such as cell chemistry, size, and pack materials.

redundant

A component that is not strictly necessary to function or that duplicates another component's function. Redundant parts can increase weight and reduce efficiency in EVs and rechargeable batteries.

relays

An electric switch that opens and closes a circuit using an electromagnetic coil. Relays can open or close one or many sets of contacts and are designed for small current loads.

repairability

The ability to be serviced or fixed. Repairability influences electric battery design choices such as cell geometry, size, and pack design.

robots

A mechanized device that can be programmed to automatically manipulate materials, parts, tools, and other devices to perform a variety of tasks. Robots often perform complicated and repetitive tasks.

secondary cell batteries

A battery that can be recharged. Secondary cell batteries, or rechargeable batteries, are charged by running electrical current back through them to restore their chemical energy.

semiconductors

A material or element that has more electrical conductivity than an insulator, but less than a conductor, or a device that uses a semiconductor material. Semiconductors are critical for microelectronics and other components in rechargeable batteries.

sensors

A device that detects a change in physical and environmental conditions and sends out an electric signal in response. Sensors in a battery pack may be used to track variables such as temperature, voltage, and state of charge.

series

Connected end-to-end along a single electrical path. In series, the negative terminal of one battery cell is connected to the positive terminal of the following cell to increase a battery pack's voltage.

series-parallel

Connected in series, then in parallel. In series-parallel battery packs, individual cells are connected in series, then groups of series cells are connected in parallel to increase a battery pack's voltage and capacity.

service disconnect

A plug or switch that electrically isolates the battery pack from the rest of a vehicle's systems when activated. The service disconnect must be removed, and the battery must be appropriately discharged, before beginning maintenance or repair work.

simulation

A computer creation of a virtual space and activity. Simulations allow engineers to design rechargeable batteries and predict how they will perform before designs are implemented in production.

smart

Able to connect to and send data across the internet. Smart devices can track performance without human intervention.

solar power

Electrical energy converted from sunlight. Solar power storage systems commonly use rechargeable pouch battery cells.

soldering

A joining process in which a filler metal is melted at temperatures below 840°F (450°C) to form a joint between two base metals. Soldering is often used for delicate projects, such as electronics in rechargeable batteries.

structural batteries

A battery that adds integrity to a vehicle's frame. Structural batteries include cell-to-body, or cell-to-chassis, batteries, which can reduce part redundancy while adding support and rigidity to an EV.

surges

A sudden, large, but typically brief increase in voltage or current in an electric circuit. Surges can damage sensitive battery components.

sustainable

Capable of being maintained with fewer or no negative impacts on the environment. Rechargeable batteries are an important sustainable technology because they produce zero greenhouse gas emissions during operation.

swelling

An abnormal expansion in a battery cell. Swelling is caused by gas buildup in old, damaged, or degraded battery cells and can lead to explosions and fires.

switches

A control device that opens and closes contacts in a circuit. Switches can operate manually, mechanically, or automatically.

terminal

A conductive component on an electrical device to which other components can be attached. Terminals have a negative or a positive charge.

thermal interface materials

TIMs. Any material that dissipates or conducts heat between two or more contacting surfaces. Thermal interface materials in battery packs include cushions, adhesives, seals, and other components.

thermal sensors

A device that measures the heat or temperature of a component or in a given space. Thermal sensors include thermistors, thermometers, and infrared (IR) sensors.

TIMs

Thermal interface materials. Any material that dissipates or conducts heat between two or more contacting surfaces. TIMs in battery packs include cushions, adhesives, seals, and other components.

vibrations

A rapid, continued, repeated motion in a machine or other structure. In EVs, vibration can be produced by rough handling, poor road conditions, and other wear and tear on the vehicle.

voltage

The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts (V).

volts

V. A unit of measurement that indicates the amount of electrical force or pressure in a circuit. Volts measure voltage, which is also known as electromotive force.

volume

A measure of the amount of space a three-dimensional object occupies. A battery's volume in liters (L) can be used to determine its energy density.

watts

W. A unit used to measure electrical power that is equal to one ampere multiplied by one volt. A watt is 1/1,000th of a kilowatt.

welding

A joining process that uses heat, pressure, friction, or a combination of methods to fuse two materials together permanently. Welding can be used to permanently secure components and seal housings for rechargeable batteries.