1. What is Motor kV?

Motor kV (kilovolt) is a rating that indicates the RPM (revolutions per minute) a motor will turn per volt applied, with no load. It's a key specification for electric motors, especially in RC and drone applications.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( kV \) — Motor constant (RPM per volt)
• \( Voltage \) — Applied voltage (V)
• \( RPM \) — Resulting revolutions per minute

Explanation: This gives the theoretical maximum RPM with no load. Actual RPM under load will be lower due to various factors.

3. Importance of RPM Calculation

Details: Knowing the expected RPM helps in motor selection, propeller matching, and ensuring your system operates within safe and efficient parameters.

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: What affects actual RPM vs calculated RPM?
A: Load, efficiency losses, battery voltage sag, and temperature all reduce actual RPM below the calculated value.

Q2: How does kV relate to motor power?
A: Higher kV motors spin faster at a given voltage but generally have less torque. Lower kV motors have more torque but lower top speed.

Q3: What's a typical kV range for drone motors?
A: Typically between 1000-3000 kV for small drones, with lower kV (200-800) for larger drones and industrial applications.

Q4: Can I use this for brushless and brushed motors?
A: Primarily for brushless motors. Brushed motors have different characteristics and this formula may not apply directly.

Q5: Why is my actual RPM lower than calculated?
A: This is normal due to load, inefficiencies, and voltage drop under load. The calculation shows ideal no-load RPM.