Electric Vehicle Battery Modules and Packs

Most EV owners can’t truly appreciate the amazing technologies of EV batteries. Some even make the mistake in thinking that the EV battery pack inside their car is just a single battery, when in reality, it actually consists of a number of individual cells.

But that is the beauty of EV battery design. It is because of continuing and evolving research in EV battery components that this design is being upgraded and refined for improved driving range, longer life expectancy, recyclability, and sustainability.

Here, we shall take a closer look at EV battery pack design.

EV battery cell, module and pack: key differences  

You may have heard various terms related to EV battery design, but perhaps thought them to refer to a single unit, when they really refer to different elements.

As a refresher:

• EV battery cells are the individual, basic units. Each one stores chemical energy and comes in the following forms: cylindrical, pouch, and prismatic.
• EV battery modules each consist of a number of EV battery cells connected in series or parallel, forming units that produce the required voltage and energy capacity.
• EV battery packs are the final product, assembled as well in series or parallel within a hard housing. They may also contain other components, including monitoring software and thermal management.

EV battery design elements 

As you can see, EV battery design has the elements arranged in a specific hierarchy. This hierarchy has evolved from continuing improvements in battery technologies.

EV battery cells come in a variety of cell chemistries, of which lithium-ion is the most popular. It can deliver one to six volts per cell. EV battery cells are available in three specific sizes and shapes: cylindrical, prismatic, and pouch.

After the assembly of these cells, they are connected to current collector plates to form EV battery modules. The cells in these modules are connected in a specific configuration in order to achieve the desired power output.

Modules are then assembled to form the EV battery pack, which is the final deployable battery system. The modules are also assembled in specific configurations to achieve output levels that can meet the power requirements of the various applications in an electric vehicle.

EV battery pack design components

As previously mentioned, EV batteries may have other components that can ensure good power distribution, excellent electrical performance, and safety.

Here are some key EV battery components that you should know:

• Electrical connectors connect individual cells and modules inside the battery pack (e.g. EV busbars, wires, and other distribution connectors).
• Thermal interface materials (TIMs) are substances placed between battery components, joining them together and according thermal management properties on surfaces.
• Battery Management System (BMS) protects the cells by monitoring the vital parameters in an EV battery (i.e., voltage, current, temperature). Comes with a failsafe mechanism to shut off the battery when necessary.
• Battery Thermal Management System (BTMS) maintains the thermal energy and temperature in an EV battery, heating or cooling it down as needed.
• Contactor System can switch off the connection between the main battery and the high voltage bus.
• Housing refers to the robust enclosure that protects the battery from various environmental factors that may cause corrosion, fire, and other hazards.
• Communications System maintains constant communication between the various EV components.

Main battery pack designs

There are four main battery pack designs described below:

Hybrid battery packs

Commonly found in HEVs, small hybrid battery packs function in complement to the larger internal combustion engine (ICE). They are ideal for short distance trips (i.e., 30-50 miles), with longer distances reserved to the ICE.

EV battery packs

EV battery packs are full-sized batteries capable of powering an entire electric vehicle. The heaviest part of an EV at an average weight of 1,000 lbs (450 kg), it has an average range of 200 miles.

High performance battery packs

These are special battery technologies specifically designed for Formula E races. These ultralight and energy-efficient batteries are easily replaceable during races, but are capable of delivering hundreds of kWh of power.

12V battery packs for accessories

12V battery packs provide power to low energy accessories and applications in a vehicle, such as headlights and radio.

How EV battery packs are manufactured

Manufacturing of EV battery packs begins with the individual cell. The components of the cell are first assembled together, namely the anode and cathode with a separator in between and then immersed in electrolyte fluid. These components are contained in a rigid casing.

Prior to assembly into EV battery modules, the individual cells undergo specialized testing, including checks for leakages of electrolyte (which may cause fire or explosion) and moisture intrusion. It is imperative that cells function properly and deliver the required power output  without compromising the battery capacity.

Next, the cells are removed from their packaging and assembled into modules. The modules are stacked in series or in parallel within a robust metal housing that protects the cells from shock, vibration, and other environmental factors.

Finally, the modules are assembled, again in series or in parallel, into a sturdy battery pack housing. Further tests and fine-tuning are done, including power output checks and ensuring electrical connections are working properly, prior to installing the EV battery pack into the electric vehicle.

The bottomline

Looking ahead, the future of EV battery technology holds great promise for car owners. Innovations are expected to lead to batteries that charge faster, last longer, and are made from more sustainable materials. Such advancements will not only enhance the ownership experience by offering longer ranges and reduced maintenance but also contribute to the broader adoption of electric vehicles by making them more convenient, affordable, and environmentally friendly.

As researchers continue to push the boundaries of what’s possible, the future of EV technology looks bright, offering exciting prospects for improved performance, sustainability, and accessibility for car owners worldwide.