1. What is Motor kV Rating?

The kV rating (RPM per Volt) of a motor indicates how fast the motor will spin when a specific voltage is applied with no load. It's a key specification for brushless DC motors used in drones, RC vehicles, and other applications.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( kV \) — Motor's kV rating (RPM per Volt)
• \( Voltage \) — Applied voltage (Volts)

Explanation: This gives the theoretical maximum RPM with no load. Actual RPM under load will be lower due to factors like voltage drop and motor efficiency.

3. Importance of RPM Calculation

Details: Knowing the motor's expected RPM helps in selecting the right motor-propeller combination, predicting performance, and ensuring components operate within safe limits.

4. Using the Calculator

Tips: Enter the motor's kV rating (found in its specifications) and the voltage you plan to use. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Is this the actual RPM under load?
A: No, this is the theoretical no-load RPM. Actual RPM under load will be lower due to voltage drop and motor efficiency.

Q2: How does battery voltage affect RPM?
A: Higher voltage increases RPM proportionally (for the same kV motor), while lower voltage decreases it.

Q3: What's a typical kV range for drone motors?
A: Typically 100-3000 kV, with lower kV for larger props and higher kV for smaller props.

Q4: Can I use this for brushed motors?
A: No, brushed motors don't use kV ratings. This calculator is specifically for brushless motors.

Q5: Why is my actual RPM lower than calculated?
A: Factors like battery sag, ESC efficiency, propeller load, and temperature all reduce actual RPM below the theoretical maximum.