Battery Pack Configurations
Battery pack configuration describes how individual cells are physically arranged and electrically connected to achieve the required voltage and capacity. Configuration choices are driven by cell type, chemistry, dimensional constraints, and electrical requirements. Common cylindrical cell layouts include linear, multi-row (cubic), nested, and circular configurations, each with distinct space and assembly tradeoffs.
Battery pack configurations are defined by how cells are connected in series and parallel to deliver the desired electrical output while fitting within a specific dimensional envelope. Key drivers include battery chemistry, cell format, target voltage and capacity, and available space within the product enclosure.
While there are many possible combinations, most cylindrical-cell battery packs follow a small set of common physical layouts. These configurations balance electrical performance, manufacturability, mechanical stability, and overall pack size.
Pure nickel bus material with spot welding is the most commonly used interconnect method. For designs requiring higher pack amperage, bus material selection becomes a more critical design factor.
At a Glance: Battery Pack Configurations
- Battery pack configuration defines how cells are physically arranged and electrically connected to achieve the required voltage and capacity within a given space.
- Common cylindrical cell layouts include linear, multi-row (cubic), nested, and circular configurations, each offering different tradeoffs in packing density and dimensional efficiency.
- Configuration selection is driven by cell type, chemistry, enclosure constraints, and mechanical considerations such as interconnects and cell support.
Linear (F-Type / L-Type) Cell Configurations
Linear configurations arrange cells end-to-end in a straight line. This approach is often used when the enclosure favors elongated shapes or narrow profiles.
Typical construction involves:
- Standing cells side by side
- Welding a nickel strip across the terminals
- Bending the nickel strip into a “U” shape to connect cells end-to-end
Dimensional planning must account for the folded nickel tabs. Each junction typically adds approximately 0.5 mm to 1 mm of thickness, which must be included in the overall pack dimensions.
With a connector and heat shrink wrap
Some construction views to show how the battery packs are fully assembled
Multi-Row (Cubic) Cell Configurations
Multi-row, or cubic, configurations arrange cells in neat rows and columns. This structured layout is commonly used when multiple cells must be packaged efficiently in a rectangular volume.
The approximate size of a cubic pack can be expressed as:
- nD × mD × H
Where:
- n = number of cells per row
- m = number of rows
- D = cell diameter
- H = cell height
This configuration provides predictable dimensions and simplifies mechanical integration.
Nested and Face-Centered Cubic Configurations
Nested configurations use a staggered cell arrangement to reduce wasted space between cylindrical cells. Electrical connections follow the same principles as cubic layouts, using the same nickel tab materials and welding methods.
Additional construction features commonly include:
- Outer heat shrink wrap to provide mechanical support
- Fish paper to protect exposed cell ends
In some designs, cells are potted to further support the structure and protect the complete battery pack. Nested and cubic configurations are both acceptable and should be evaluated based on handling, protection, and transportation requirements.
Face-centered cubic packing is a form of nested configuration designed to occupy less volume, though dimensional calculations require more complex geometry.
Photo of custom nested cell pack to the right:
Face centered cubic packing is nested to take up less room. Calculating the size takes a little geometry.
Circular Cell Configurations
Circular configurations are commonly used when the battery pack must fit within a cylindrical enclosure. Cells are arranged around a central axis and follow the same tab welding principles as other configurations.
For circular layouts:
- The diameter of the circumscribing circle is approximately 2.41 × D
Examples using cells with a 14.2 mm diameter:
- Three cells fit within a tube approximately 30.7 mm in diameter
- Four cells fit within a tube approximately 34.22 mm in diameter
Designs should allow for up to 0.5 mm variation in cell diameter. Circular configurations can also be stacked end-to-end to increase total capacity.
Assembly and Interconnect Considerations
Across all configurations, consistent assembly practices are used to ensure reliability and repeatability:
- Pure nickel bus material for electrical interconnects
- Spot welding for secure terminal connections
- Heat shrink wrap for insulation and mechanical support
- Connector integration as required
Cell count affects lead routing:
- Even-numbered cell packs typically route both straps from the same side
- Odd-numbered cell packs route one strap from each end
Choosing the Right Battery Configuration
Selecting the appropriate battery pack configuration requires balancing electrical requirements with mechanical and spatial constraints.
Key considerations include:
- Required voltage and capacity
- Available enclosure dimensions
- Mechanical protection during handling and transit
- Assembly and manufacturability tradeoffs
Each configuration offers different advantages in packing density, dimensional efficiency, and structural support.
Frequently Asked Questions
Quick Links
- What determines a battery pack configuration?
- What does voltage mean in this context?
- What does capacity mean in this context?
- What is a circular configuration?
- What is a nested configuration?
- Why are folded nickel tabs important to consider?
What determines a battery pack configuration?
Configuration is determined by how cells are arranged and connected to meet voltage and capacity requirements while fitting within dimensional constraints.
What does voltage mean in this context?
Voltage is established by the number of cells connected in series within the configuration.
What does capacity mean in this context?
Capacity is increased by adding cells in parallel or stacking configurations, depending on available space and design goals.
What is a circular configuration?
A circular configuration arranges cells within a cylindrical boundary, making it suitable for tube-shaped enclosures.
What is a nested configuration?
Nested configurations stagger cells to reduce unused space while using the same electrical interconnection methods as cubic layouts.
Why are folded nickel tabs important to consider?
Folded nickel tabs increase pack thickness at each junction and must be included in dimensional planning.
Unsure of the Battery Configuration You Need?
Work with experienced battery engineers to evaluate configuration options and select the layout that best meets your voltage, capacity, and dimensional requirements.
Request a Quote Request Design Support Request More InformationRequest a FREE Quote!
We are here to help you will all your custom battery pack needs.
Get Your Quote Now! Not Ready for a Quote? Request more info or email us your inquiry.Ebook - BMS Design Guide for Custom Battery Packs
Download Your Copy
...or Download Our Custom Battery Pack Design Guide