1. What is an EV Motor Size Calculator?

Definition: This calculator determines the power requirement (in watts and kilowatts) for an electric vehicle motor based on torque and RPM.

Purpose: Helps EV designers and enthusiasts properly size electric motors for vehicle applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P_w \) — Power in watts
• \( T \) — Torque in pound-feet (lb-ft)
• \( RPM \) — Rotational speed in revolutions per minute
• \( 2\pi \) — Constant to convert torque to work
• \( 60 \) — Converts minutes to seconds

Explanation: The formula calculates the mechanical power output required from the motor based on the torque and rotational speed.

3. Importance of Proper Motor Sizing

Details: Correct motor sizing ensures optimal vehicle performance, efficiency, and battery life while preventing overheating or underperformance.

4. Using the Calculator

Tips: Enter the required torque in lb-ft and the desired operating RPM. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine the required torque?
A: Torque requirements depend on vehicle weight, wheel size, and desired acceleration. Use a vehicle dynamics calculator.

Q2: What's a typical RPM range for EV motors?
A: Most EV motors operate between 2,000-10,000 RPM, with some high-performance motors reaching 15,000+ RPM.

Q3: How does this relate to battery requirements?
A: Motor power determines battery current requirements. Higher power motors need higher capacity battery systems.

Q4: Should I add a safety factor?
A: Yes, consider adding 10-20% to the calculated power for headroom and efficiency losses.

Q5: How do I convert lb-ft to Nm?
A: Multiply lb-ft by 1.3558 to get Nm. The calculator works with either unit as long as you're consistent.