Busbar Ampacity Calculator

Busbar Thickness Calculator

Busbar Thickness Calculator

Enter the desired ampacity (in amperes) and width (in inches) to calculate the minimum thickness for copper and aluminum busbars, designed for minimal heat generation. For example, many lifepo4 prismatic cells will use busbars that are 1" wide. If you need to carry 300 amps you would need roughly 1/8" thick copper or 1/4" thick aluminum busbars.

Ampacity (A):

Width (inches):

 

Busbar Thickness Calculator Explanation

This calculator helps you determine the minimum thickness required for copper and aluminum busbars based on your specified ampacity (the maximum continuous current the busbar needs to carry) and smallest width of your required busbar size. The calculation is designed with conservative current densities to minimize heat generation, ensuring safe and efficient operation.

How the Calculator Works

1. Input Specifications:

   • Ampacity (A): This is the maximum continuous current (in amperes) that the busbar should be able to conduct safely.
   • Width (inches): The minimum width of the busbar in inches. For example lifepo4 prismatic cells often require a busbar size of about 3" x 1" to connect 2 cells in series. In this case you would enter that 1" size into the calculator since that is the smallest width.

2. Material Selection:

   • The calculator provides results for two materials: copper and aluminum. These materials are chosen due to their common use in busbar applications, differing mainly in their electrical conductivity and cost. The most common and recommended aluminum alloy is 6101.

3. Current Density Assumptions:

   • Copper: 4 A/mm² (Ampere per square millimeter)
   • Aluminum: 2 A/mm²
   • These values are intentionally chosen to be conservative to prevent heat generation and ensure that the busbars operate within safe temperature limits. The actual current density can be higher, but using these lower values helps in designing a safer busbar under various operating conditions.

4. Calculation Steps:

   • Convert the width from inches to millimeters because the standard unit for current density is in square millimeters.
   • Calculate the required cross-sectional area (in square millimeters) using the formula:
     $$\text{Area}=\frac{\text{Ampacity}}{\text{Current Density}}$$
   • Determine the minimum thickness required by dividing the calculated area by the width (converted to millimeters). This gives the thickness in millimeters.
   • Convert the thickness from millimeters to inches to provide a user-friendly result.

5. Output:

   • The calculator outputs the minimum thickness in inches for both copper and aluminum busbars. These thicknesses are the minimum required to safely carry the specified current under the assumption of minimal heat generation.

Why Use Conservative Current Densities?

Using conservative current densities in the calculation helps in accounting for unforeseen variations in operating conditions, such as ambient temperature fluctuations and installation variances that might affect the actual current-carrying capacity and heat dissipation of the busbar. This approach ensures that the busbar design is robust and reliable under a variety of conditions.