What is Kv in a Drone Motor? (Explained)

What is Kv in a Drone Motor? (Explained)

You might need heard folks discuss Kv scores of drones and be questioning what on this planet they’re speaking about. Not to fret, on this article, you’ll be taught all you could learn about Kv scores of drones and you might even be capable of contribute a factor or two while you hear folks speaking about Kv scores. Read on to be taught extra about Kv scores. 

“Kv” (to not be confused with “kV” the abbreviation for kilovolt) talks in regards to the fixed velocity of a motor. Therefore, the Kv score for a motor is a sign of the variety of revolutions per minute (RPM) of the motor when a given voltage is equipped.

How does this apply to drones? You in all probability know that motors are one of many key parts of a drone, which in flip makes the Kv scores of a drone’s motor crucial. We’ll be speaking extra about Kv scores under and the way this score has an impression on the efficiency of your drone.

What is Kv within the Motor of a Drone?

Remember we stated Kv score is a sign of the variety of RPM {that a} specific motor could make when a given voltage is utilized. Usually, the voltage utilized is 1 Volt present. This voltage is normally utilized with none load hooked up to the motor. 

Let’s use the Hyperion 3025/6, which is specified to have a Kv score of 1255, for example. The Kv score of 1255 means the motor of the Hyperion 3025/6 can rotate at 1255 RPM while you apply 1 Volt present with none load. There is a discount of the RPM of the motor while you connect a propeller to it due to air resistance.

How Kv Rating Varies

The Kv score of a motor will depend upon the exerted energy (or in different phrases, the torque stage) of the motor. Also, the variety of copper wire windings on the rotating coil of the motor (the armature) will even decide the Kv score. In common phrases, the upper the variety of copper windings on the rotating coil of the motor, the upper the Kv worth and vice versa.

Also, the Kv score of a motor relies on magnetic energy. An enhance within the magnetic energy of the motor will even result in a rise within the Kv worth.

Why the Kv Rating of a Drone Motor Matters

There are a number of causes the Kv score is essential so that you can know. We’ll go into a couple of of them right here:

For Avoiding Overloading Incidents

One of the purposes of the Kv score of a motor is within the willpower of the velocity of the motor at a selected voltage. Let’s use a motor with a Kv score of 900 for example. If stated motor is powered by a lithium polymer battery that has a Kv worth of 11, then the motor would rotate at 9900 rpm (900 x 11 = 9900). 

Any change within the utilized voltage should be associated to the change within the rpm. And this can finally require an adjustment within the propeller of the motor with a purpose to keep away from the danger of overloading the motor.  

For Distinguishing Two Similar Motors

Two motors could also be very related of their configurations however have completely different windings (copper windings on the coil of the motor). So a simple option to make a comparability and distinguish the 2 related motors is by the Kv score. Since Kv scores depend upon the variety of windings of the motors, the 2 in any other case equally configured motors can have completely different Kv scores.

Reducing the Risk of Overheating

As a rule of thumb, motors which have excessive Kv scores must be used for lighter drones whereas motors with low Kv motors must be used for heavier drones. It’s essential to comply with this fundamental rule as utilizing motors with excessive Kv scores for heavy drones or motors with low Kv scores for lighter drones will enhance the danger of overheating and consequently burning out the motor. 

We know you’re curious as to why that is so and are longing for extra clarification. Everything can be made clear under as we’re nonetheless going to speak about how to decide on motors for drones based mostly on Kv scores. But the brief clarification is pairing a excessive Kv motor with a heavy drone (which can have a big propeller) will result in the motor attempting to rotate the propeller at a excessive rpm. This requires extra torque and consequently, extra present. Ultimately, a whole lot of warmth can be generated which can most definitely result in untimely failure of the motor. Yeah, not cool. 

Brushless Motor Kv Rating Explained

Brushless and brushed motors are the 2 hottest kinds of motors. While each of them are designed on the identical bodily rules, there are important variations of their construction, management, and efficiency. 

A brushed motor makes use of wound wire coils (brushes), additionally known as the arms tire as a two-pole electromagnet whereas a brushless motor makes use of a everlasting magnet as its exterior rotor. The benefit of eradicating the brushes in brushless motors is improved working effectivity, much less general upkeep, and decrease electrical noise era, amongst others. As a outcome, brushless motors have gained a whole lot of reputation and have turn out to be the motor of selection in lots of drones.

The Kv motor score of a brushless motor is essential because it determines different elements and parameters of the motors such because the effectivity, function of the drone, agility of the drone, flight time, dimension of the propeller, flight time, and so forth. 

You’ll additionally be capable of perceive the torque of a brushless motor based mostly on the Kv score because the torque can be decided by the energy of the magnet. Also, your information of the Kv score of a brushless motor will turn out to be useful if you end up attempting to find out which motor must be utilized in a selected plane. For instance, an FPV racing quadcopter would require a motor (higher whether it is brushless) that has a excessive rpm (for top velocity). So this implies you want a motor with a excessive Kv score however a propeller with a small diameter. 

On the opposite hand, while you encounter a motor with a low Kv worth, you’ll most definitely need to use it in a heavy plane with a purpose to get extra torque to spin the heavier prop.

How to Choose the Right Kv Motor for a Drone

By now, you need to have understanding of the Kv score of motors. This heading will give attention to how to decide on a Kv motor for a drone, one thing you might have already got an concept of if you happen to’ve been being attentive to every little thing to this point. 

I’d prefer to shortly remind you that the Kv score of a motor is decided by the variety of copper wire windings on the motor (for brushed motors) or the energy of the magnet (for brushless motors). The larger the variety of copper wirings or the energy of the magnet, the upper the Kv worth, and vice versa.

The measurement of your drone is the most important figuring out issue of the Kv score of the motor you’re going to need to use. If your drone is mild, then it makes probably the most sense to make use of a excessive Kv motor. Lighter drones will even have small propellers and through the use of a excessive Kv motor, the motor will need to spin the propeller sooner, an act that can be profitable as a result of small measurement of the prop. As a outcome, excessive Kv motors are utilized in lighter drones or racing drones the place velocity is prioritized. 

On the opposite hand, heavier drones, which can have bigger props, would require a low Kv motor. A low Kv motor will be capable of rotate the motor with none drawback and also will be capable of generate the excessive torque wanted to elevate the motor. But must you use a excessive Kv motor for a heavy drone, the motor will try and rotate the bigger propeller at a excessive velocity. This would require extra energy from the motor and pressure the motor to attract extra present. As this occurs, overheating will occur and the motor will find yourself being broken. 

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