In this article we take an in-depth look at electronic speed controllers - or ESC's. These pieces of hardware connect between your flight controller and motors. They drive your motor from the PWM signal your flight controller sends. It is important to use high quality ESC's for a smooth and reliable flight experience.

Component Spotlight: Electronic Speed Controllers

This article is part of a series that covers the entire concept of quadcopter parts, how they work, and how they come together. For further reading, see the master article: Components & Anatomy of an FPV Quadcopter

Important ESC Features

Current Rating + Burst

Your motor and propeller combination determine the max current draw at full throttle. Your ESC's must be able to support this demand. Before buying speed controllers, it is important to understand this concept. Static thrust tests give you a reference point for current consumption. You will rarely fly at 100% throttle for extended periods of time without release.

Flyduino KISS 24a Race Edition ESC

Choosing a current rating to support the draw of your motor is the first and most important factor to consider when choosing ESC's. ESC's all carry a current rating and some display a burst rating - often marked as 10A, 20A, 30A etc. Buying electronic speed controllers that have an excess current rating for your setup will not improve performance. They will only be overkill and will likely add some unnecessary size and weight.

Hardware PWM Driver

A rapid set of electronic switching chips called FET's drive the motors. They are rapidly switched on and off. This sends the correct signal to your motors. Before the introduction of hardware PWM drivers on ESC's, this task was handled by the flight controller. When FlyDuino released the first line of hardware PWM drivers on the KISS ESC's, the difference in flight quality became obvious.

Since that time, new companies have integrated hardware PWM's and BLHeli_S has been created to support them.

ESC Location Diagram

ESC Mounting Locations


The firmware is programmed onto your ESC's. Most modern components will come with the appropriate firmware pre-loaded. There are currently 3 major firmwares that run on miniquad ESC's:


This was one of the earliest open source firmwares developed. It was much more difficult to flash and doesn't perform as well. This firmware is becoming obsolete and is not being supported or updated.


This open source project took the flame from SimonK as it was much easier to flash and configure via the BLHeliSuite GUI. Better performance and support has made this the most popular firmware on the market.

KISS ESC Firmware

This firmware is exclusive to the KISS line of electronic speed controllers. It is a closed source project that supports the hardware PWM found on their line of hardware. This firmware is used exclusively on FlyDuino's KISS hardware.


This new firmware supports ESC's featuring a hardware PWM. Brands like Aikon and DYS are some of the earliest adopters of the hardware PWM. Many brands are now catching up and BLHELI_S is commonplace.


There are many processors on the ESC market today, but the main 3 manufacturers are ATMEL, Silabs and Busybee. ATMEL is becoming dated as the Silabs F330 and F390 series outperform them. Busybee1 and Busybee2 processors found on the latest ESC's are running BLHeli_S and supporting hardware PWM.

A recent development has seen a jump from 8bit to 32bit ARM processors similar to those on flight controllers. New chips offer great potential, and the firmware market is starting to catch up with the likes of BLHeli_S and the DShot protocol.

LiPo Support

Common ESC's for mini quads are going support 3-4 cell LiPo's. Recent increases in battery demand have seen pilots jumping up into 5 and 6 cell batteries. You will need specially rated ESC's to support these high cell count batteries. Manufacturers specify the LiPo rating for each product they sell. For more information on LiPo batteries, see our article on the subject.

Choosing the Right ESC

Now that you understand the main features and specifications to look out for, it's time to pick the right ESC for the job. Here at Controller Craft we catalog products from all around the industry. Browse the Electronic Speed Controller section to find the right hardware for your next build. 

Last updated on February 6, 2017

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