EV Busbar Weight, Cost and Power Loss Calculator
Busbars carry the high current between cells, modules, contactors and the inverter in an electric vehicle. This calculator gives mass, material cost, DC resistance and resistive loss for a straight rectangular bar so you can compare copper and aluminum quickly.
Your numbers
Pick the same material as above.
Use your current metal plus fabrication premium.
Your results
DC bulk resistance at 20 C only. Skin effect, temperature rise, joints, plating and ampacity limits are not modeled. Verify with thermal testing.
Power loss per bar (W) vs current (A)
Sweeps Continuous current from 0 to 500, holding your other inputs fixed.
Cost roll up for EV components
Optional: discuss how to tie metal prices and bar geometry to standard cost in your ERP.
Optional. The tool and every export work without this. No spam.
How to use it
Enter the cross section and length of the bar, then pick the material and its matching resistivity. Add a blanking scrap allowance, since stamped or laser cut blanks leave offcut. The result is a first pass material cost and loss estimate, useful for quoting, early design trades and checking supplier quotations.
- Keep the material and resistivity selects aligned
- Add plating and bending cost separately
- Check loss at the peak current as well as continuous
Formulas
Mass equals volume times density. Resistance equals resistivity times length over cross sectional area. Voltage drop equals current times resistance, and power loss equals current squared times resistance. Copper has roughly one third the resistivity of aluminum but is more than three times as dense, so an equal resistance aluminum bar needs about 1.6 times the area and still weighs roughly half as much.
Reading the result
Loss grows with the square of the current, so doubling current quadruples the heat. Use the chart to see where the loss becomes a thermal problem. Aluminum saves weight but needs larger sections and careful joint design because of oxide formation and creep at bolted joints.
Common mistakes
Do not size solely on resistance, since the real limit is temperature rise in the enclosure. Do not forget contact resistance at bolted or welded joints, which can exceed the bar's own resistance on short bars. Avoid applying this to laminated or flexible busbars without adjusting the cross section.
Frequently Asked Questions
Is aluminum busbar cheaper than copper?
Usually by raw material mass cost, yes, but the larger cross section, plating and joining process can erase the saving. Compare the finished assembly cost and weight, not just the metal price per kilogram.
What density does copper have?
About 8.96 grams per cubic centimeter for pure copper and about 2.70 for aluminum. Alloys vary slightly, so use your material certificate for tight cost work.
Does this give ampacity?
No. Ampacity depends on temperature rise, cooling, enclosure and insulation. Use the power loss result as an input to a thermal analysis or test, not as a rating.
Why does the result differ from my CAD mass?
CAD includes holes, bends and chamfers. This tool treats the bar as a solid rectangle. Use the CAD net mass for final cost and keep the scrap allowance for the blank.
For suppliers who quote many busbar variants, Netray can help connect item master geometry and metal price data in your ERP so cost roll ups follow engineering changes automatically.
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