While designing a lithium battery pack, it is the cells that receive the maximum attention. It is common for engineers to think about cell chemistry, capacity, thermal management, and electrical configuration. However, one more component can also have an impact on the design of the pack: the busbar.

The design of the busbar should ensure that it succeeds in carrying current but at the same time does not require much space between the cell and other parts. The size of the busbar, as well as its thickness, width, length, angles, holes, space for any other wires, and materials for its manufacturing, will determine the efficiency of using space.

The custom-designed busbar plays an important role in this case.

For battery manufacturers using prismatic lithium cells, a busbar designed around the actual cell layout can help reduce unnecessary material, avoid wasted space and support a more compact electrical connection.

Adinath Enterprises specializes in manufacturing custom copper and aluminum busbars based on client drawings and specifications given their intended application in prismatic lithium batteries.

What Are Busbars in Battery Pack Design?

Designing a busbar for a battery pack involves several decisions about the type of material and the shape and dimensions of the busbar, as well as details such as holes, bends, and connection points of the busbar.

The busbar must fulfill certain functionality, such as

• Conduit the required current

• Fit within the battery pack dimensions

• Correspond with the terminal arrangement of the cells

• Provide electrical connections

• Keep mechanical off-sets

• Follow the manufacturing specification of the battery.

• Be compatible with connecting methods used by the customer

Thus, designing a busbar implies much more than just getting a piece of copper or aluminum and cutting it into shape.

How Busbar Design Influences Battery Pack Energy Density?

Energy density is a term referring to the amount of energy that a battery can store in relation to its mass or volume.

The busbar does not add any energy to the cells. But the design of the busbar can affect how well space and weight are utilized in the area of the cells.

A bad busbar design can result in:

• More materials being used

• Bigger clearances

• Needless bends

• More space being required for installation

• More insulation or support components being required

The busbar that is designed correctly does follow the shape of the available geometry better than the busbar that is not designed correctly.

For instance, if using a straight busbar makes it impossible for a manufacturer to leave enough space around a terminal, a bent or shaped design will be able to achieve this.

It doesn’t mean that the capacity of the cell increases by some means, but it definitely allows the battery assembly to use the space possible in a better way.

1. Compact Busbar Geometry Optimizes Space Usage

Prismatic cells in battery packs typically have major space limitations.

An excessively long and improperly shaped busbar could hinder nearby components, so designers may have to change the spacing or arrangement.

Busbars can be built according to the relevant specifications, which may include various design possibilities like

• Bends used to follow the battery pack shape

• Slots wherever adjusting or positioning is needed

• Holes precisely located for bolted connection functionality

• Formed shapes that clearly surround objects

• Length optimized to eliminate unwanted use of materials

The aim is not to design the smallest busbar; it’s to design the busbar fulfilling the electrical and mechanical requirements while maximizing beneficial use of space.

2. Busbar Weight Has Greater Significance Than It Might Appear

Copper is a great conductor of electricity; however, its density is also relatively high. Aluminum, on the other hand, is a lighter alternative for the case when the situation permits.

Thus, the choice of material becomes important in battery busbar design.

When providing electrical performance, engineers also need to take into account the following items:

• Magnitude of the current

• Sectional area

• Requirements regarding mechanical performance

• Mode of connection

• Dimensions

• Target weight

• Manufacturing issues

In certain battery applications, aluminum busbars can be used to reduce the weight of conductors. In other cases, copper would be the better fit due to its electrical and mechanical properties.

There isn’t one material that’s automatically best for every battery pack.

The correct choice depends on the actual application and technical requirements.

3. Busbar Size Impacts More Than Just Ability to Carry Current

Busbar width and thickness are usually talked over mainly in terms of current-carrying ability. The above is just a part of the design work.

The dimensions affect the physical integration of this element.

Consider the example of increasing busbar thickness—it will increase cross-sectional area; however, it will affect the following:

• Clearance

• The need to bend the busbar.

• The height of the connection.

• Space for the assembly.

• Weight.

• Manufacturability.

In a similar way, working out a thicker busbar makes its conducting area larger; however, the increased dimension would disrupt other neighboring cells or components.

This stresses the importance of the combination of calculations and layout of the busbar.

4. Curves Can Enhance Battery Pack Distribution

A direct connection is not always the best course of action.

In a densely designed battery pack, a properly positioned curve can allow a busbar to go around a part or get straight to its terminal or retain a necessary distance.

This aspect is particularly important for specialized prismatic cell busbars.

Depending on how the busbar is designed, it can have some of the following components:

• 90-degree bends

• Offsets

• Areas with a specific shape

• Rising and falling parts

• Multiple connection points

The overall shape depends on the client’s battery design.

Adinath Enterprises manufactures drawing-based copper and aluminum busbars as per the design specifications and requirements provided by the customer.

5. Importance of Correct Location of Holes and Slots

A small mistake can cause a big problem in assembly.

When holes are not aligned correctly with the correct terminals or fasteners, the busbar will not be installed properly.

Design of holes and slots impacts:

• Alignment of terminals

• Fastening

• Assembly duration

• Mechanical clearance

• Electrical connection

• General fit of the busbar.

Therefore, the dimensional control of custom busbars is an important operation.

When it comes to battery applications, it is necessary for engineers to provide all necessary data about hole size, center-to-center distances, slot sizes, locations of bends and tolerances, among others.

Errors in Busbar Design

Busbar design can prevent occurrences of errors.

1. Designing only for current requirements

It is possible that while a busbar can conduct enough current, it is not suitable for the application.

Better approach: Consider electrical and mechanical requirements at the same time.

2. Ignoring the available space

It may seem easy to manufacture a straight busbar, but it may waste a lot of space.

Better approach: Base the design on the actual location of cells and components.

3. Using excessive amounts of materials

Using unnecessary length, excess width, and unnecessary features can result in additional expenses both in terms of weight and manufacturing costs.

Better approach: Use the optimal design while taking into consideration both electrical and mechanical needs.

4. The position of holes or bends is not correct

Even little differences in size may make assembly very difficult.

Better approach: Make a drawing that shows dimensions, tolerances, and references.

5. Handling battery applications the same way

A busbar made for one type of prismatic cell cannot be appropriate for another type of cell.

Better approach: Use application-specific, drawing-based busbar manufacturer.

How Adinath Enterprises Fabricates Custom Battery Busbars

With its core expertise lying in custom manufacturing of copper and aluminum busbars, Adinath Enterprises proceeds to work on the basis of customer engineering drawings and specifications of intended application for busbars, which also include production of prismatic lithium batteries, electric vehicle batteries, energy storage stations/battery energy storage systems, inverter batteries, and other applications.

Depending on the specifications, the process of manufacturing the busbars may contain the following steps:

• Requirements analysis

• Engineering analysis

• Selection of materials

• Cutting

• Punching

• Bending

• Drilling

• Forming

• Tapping

• Chamfering and deburring

• Finishing

• Dimensional and quality inspections

• Packaging

Adinath Enterprises can manufacture busbars, the geometry of which still conforms to the cell configuration laid forth by the client in terms of terminal sizing and connection needs.

Adinath also produces aluminum busbars ready for laser welding in case the client employs that method in the course of its production.

What to Expect in a Battery Busbar Drawing

In order for a manufacturing drawing to be meaningful, it has to indicate:

• Overall height and width

• Material profile

• Material thickness

• Diameter of holes

• Inter-hole distances

• Slot dimensions

• Location of bends

• Bend points

• Shapes of parts

• Needed tolerances

• Surface quality

• Possible plating requirements

• Insulation/sleeve needs

• Quantity and version

The clearer the drawing, the easier it gets to make and control the desired busbar.

How a Well-Made Battery Busbar Can Help a Producer

A proper busbar design can assist a battery manufacturer by:

• More effective use of available space

• Less unnecessary weight of conductors

• Cleaner electrical path

• Better alignment of terminals

• More uniform assembly

• Suitable mechanical gap

• Easier making and inspection of the product

• Choice of connections suitable for a specific purpose

Usually the greatest advantage is not one specific feature of a busbar but the way it works in a complex battery-pack design.

Correct Busbar Design Before Production of Busbar System

Battery pack space is limited, and therefore every small factor can contribute to the final assembly of the system.

While a busbar alone cannot affect the battery energy density, the materials, size, and configuration of the busbar can thread to affect the space and weight of the tested electrical links at once.

For manufacturers of lithium prismatic cells, custom-made busbars should be better than turning to standard busbars in order to fit the design of the battery pack.

If you work with your battery busbar design or plan it to be performed, working with a manufacturer who is familiar with the drawing and the process of making copper/aluminum busbars based on the technical specifications can save you time moving from the designed product to the ready component.

Adinath Enterprises produces custom-made copper and aluminum busbars, which are produced according to drawings and technical parameters of the customer for the application in battery technologies.