Best ESC for Quadcopters and Multirotors

ESCs or Electronic Speed Controllers are what control how fast the motors on your quadcopter spin. For stable flight, the flight controller board determines how fast each motor should spin with the help of onboard sensors and algorithms - and then passes this to the ESCs that are attached to each motor. The ESCs then use this information received from the flight controller to control motor speed.

You could say these are the "throttle" of your quadcopter. They receive their input either from the flight controller or from the radio.

ESCs have 3 wires - one plugs into the battery, another into the receiver's throttle channel and the third lead into the motor.

ESCs compute exactly how much power to supply each motor with based on the input signal they receive from the radio or the flight controller. This page is all about choosing the best quadcopter ESC. 

Brand

Constant Current (A)

Burst (A)

BEC

Price ($)

Crazepony 4pcs Littlebee 20A Mini ESC

20A

30A

No

HOBBYMATE Quadcopter Kit Motor ESC Combo

15A

25A

No

Andoer 4Pcs Simonk

30A

40A

Yes

Hobbypower A2212 1000kv Brushless Motor + 30A ESC

30A

40A

Yes

Makerfire 4pcs BLHeli 12A ESC

12A

20A

No

GoolRC 4 Pcs 12A Brushless BLHeli ESC

12A

18A

Yes

Jrelecs 4x A2212 1000KV Outrunner Motor + 4x HP 30A ESC + 4x 1045 prop (B)

30A

40A

Yes

ESCs for Brushed and Brushless Motors

You can have either brushed or brushless motors on your quadcopter. And depending on which kind of motors you use, you will have to use the appropriate kind of ESC.

ESCs for brushed motors are totally different from ESCs designed for brushless motors.

ESCs that work with brushed motors switch the voltage they supply to the motors off and on several times per second. By regulating how long the voltage is supplied to the motor, the ESC controls the motor's speed. These ESCs - like brushed motors - have only two wires.

ESCs designed for brushless motors have three wires. The third wire always has a voltage as long as the motor is working. By measuring the voltage in this wire, the ESC determines the speed and direction of the motor, and uses this information to control the motor's speed.

Thus, using the appropriate ESC for each kind of motor is easy because brushes motors have two wires and brushless motors have three.

Selecting The Right ESC For Your Drone

Here's what you will want to look for in a ESC for your quadcopter ...

  • Maximum ampere rating

Each motor on your quadcopter has a separate ESC that provides it power. In addition to the motor, some ESCs may also power servos as well. The maximum current the ESC can handle should exceed the demands placed on it under peak conditions by all of the components connected to it. If not, the ESC can be overloaded, overheat and then burn out, leading to a crash.

That said, you would not want to use a ESC whose max amp rating far exceeds that of the demands placed on it - for the simple reason that could lead to the ESC being heavier - and more expensive - than it really should be. You want to minimize weight without compromising on the reliability of any component.

  • Refresh rates

Flight controllers send signals to the ESCs at around 400Hz. Hundreds of adjustments have to be made to the motor speeds every second in order to keep the quadcopter airborne. In case your ESCs cannot handle these kind of refresh rates, the motors will not respond as fast as they should - and that is not desirable. For the craft to be stable and very responsive to controls, the ESCs need to be fast enough.

  • ESC Firmware / Software Options

The firmware installed in the ESc is what makes sense of the signals that the ESC receives from the flight controller and then use that information to control the motor speed. Some ESCs allow you to flash them and replace the preinstalled firmware with open source programs that can be downloaded from the Internet. But that may not be always possible - in which case you will have to connect the ESC to a programmer by soldering.

Programming ESCs using a programming card is a fairly easy and straightforward process. On the other hand, using a transmitter to program ESCs is a more complicated process. ESC programming cards are available at most hobby stores and they are very inexpensive. You can use this process to tell the ESC to turn the brake off, tell it what type of batteries you are using, set the voltage cut off to low and so on.

Broadly speaking, there are three options when it comes to firmware ...

  • Traditional / standard

These are not designed specifically for multi rotors, and can be used in other ESCs - RC airplanes for instance. The needs of multi rotors and other RC aircraft like airplanes, gliders and helicopters are very different. In RC planes, the motors speeds averaged and motors speeds do not change very fast.

And airplane ESCs need only handle a 50Hz signal - which would be awfully inadequate for a quadcopter. Quadcopter ESCs need to handle signals up to a frequency of 490Hz. Using firmware that's not designed for quadcopters and multi rotors is not the best thing to do if you are really serious about the hobby. The best choices for you would be SimonK or BLHeli that are designed only for use in multirotors.

  • SimonK

This is designed specifically for multi rotors. There are quite a few different versions of SimonK software out there. It's possibly the best choice for your quadcopter's ESC because it takes motor response to the maximum - the controller makes much faster adjustments to motor speeds which makes the quad a lot more stable and responsive.

If you have been using "standard" firmware and switch to SimonK, you will notice the difference almost instantly. Your drone feels a lot more stable, responsive and easier and more fun to fly.

  • BLHeli

BLHeli is a relatively new firmware that's also designed specifically for quadcopters and other multirotors. And it offers all of the advantages of SimonK - and then some more. It offers a lot more flexibility if you want to change some setting - something that would require you to flash the firmware with SimonK.

The best thing you could do would be to buy a SimonK or BLHeli ESC with a bootloader if you are someone who changes things a lot - or if you are just getting started. But if you are really serious about drones, don't buy something other than SimonK or BLHeli.

There's just one other thing we would want to discuss about this topic - Oneshot. Oneshot125 - as its also called, is a communication protocol that allows for much faster communication between your ESC and the flight controller.For this to work, you would want to enable Oneshot on the flight controller as well as the ESCs.

This will allow the flight controller to send signals to the ESCs a lot faster, and this the motor speeds will be controlled much better leading to much better responsiveness and stability.

Both SimonK and BLHeli now support this communication protocol while traditional ESCs do not - which means apart from SimonK or BLheli, there's not much choice when it comes to ESC firmware.

Battery Eliminator Circuit

Most ESCs today have what is termed BEC or Battery Eliminator Circuit inbuilt. A few years ago, RC aircraft would have two batteries onboard - one for the receiver and another for the motors. The BEC eliminated the need for a separate battery for the receiver and reduced the need for RC aircraft to carry the additional battery.

The BEC also steps down the voltage from the lipo batteries before the supply is fed into the receiver to around 6 volts - which is what the typical receiver is designed to handle.

In addition to reducing weight by eliminating the need for a separate battery for the receiver, using a BEC has another significant advantage - you do not have to remember to charge the receiver battery. You only have one battery mounted on the quad - and if that is charged then the quad will fly. The receiver will function, the servos will work and the motors will run. You do not have to worry about the receiver battery as the BEC eliminates the need for one.

While the advantages of using a ESC with an inbuilt BEC are obvious, you would want to be aware of the risks as well...

You see, if you are using a ESC with an inbuilt BEC, you will be depending a lot on the reliability of your ESC. Your ESC would then be powering your motors, the receiver and any servos you might be using.

And if the ESC were to fail mid flight for whatever reason, your drone will crash. There will be no way you will be able to prevent that.

One of the most common reasons why ESCs fail is because of overloading. If you have too many devices connected to the ESC - and in case they draw more current than the ESC can handle, the ESC will fail.

So if you are planning to build an expensive drone with high resolution cameras and other electronics, you would want to be sure to minimize the risks associated with the ESCs failing - and ensure the ESCs never ever get overloaded in any condition. And the best way to do that would be to use an external BEC (also called UBEC or Ultimate BEC). An external BEC will handle some of the load so that the ESC doesn't get overloaded.

By using an external BEC to power the receiver, even if the ESC fails, the receiver will still work. Sometimes, that may be a good thing. Even if one of the motors fails, some flight controllers have algorithms that can detect the problem, identify which motor failed and then take corrective action to prevent a crash. These kinds of algorithms however are not available in most low cost flight controllers. Most hexacopters shut down the motor opposite the one that fails and the craft flies like a quadcopter.

Usually, ESCs with inbuilt BECs are used only in very small quadcopters where weight needs to be kept at the absolute minimum. Larger models usually have a separate BEC and do not use ESCs with built in BECs.

Throttle Calibration

The throttle range of the ESC has to match the throttle range of the flight controller or the transmitter so that they are on the same page, so to speak. If the ranges on the ESC and the radio or the flight controller do not match, your ESC could have trouble understanding what the flight controller wants it to do. Your ESC needs to know the highest and the least pwm (pulse width modulation) values your flight controller outputs.

Here's why you need to calibrate your ESC - all of the four motors should always start at the same time and they should all rotate at the same RPM. If they either do not all start together or rotate at the same speed, your ESCs are not calibrated.

Note: While calibrating or testing your ESCs, make sure propellers are not connected to the motors, the batteries are disconnected and the flight controller is not connected to your laptop or computer. This is an essential check that you would need to run before calibration or testing.

Quick Navigation

Privacy Policy