Today we come to another basic topic in the world of drones and FPV: ESCs (Electric Speed Controllers). We hope that after reading this article you will be able to make an informed choice as to which ESC is the right one for you.
Electronic speed controllers (ESCs) are devices that control the speed of motors and their direction of rotation. They are the heart of the drone, so to speak - they supply everything else with energy. How does an ESC work? The ESC receives speed and direction signals from the flight controller and makes the motor turn at the desired speed. Keep in mind that each motor turns at a different speed. The motors also rotate in different directions depending on their position on the drone and the selected setting.
A quick note on the direction of rotation: as we just mentioned, your motors can rotate inwards or outwards. You've probably seen the propeller/motor direction diagrams on quadcopters many times. Here is a cheat sheet:
You can find out more about motors here.
There are no confirmed aerodynamic advantages of one or the other. It's mainly a personal preference for each pilot. Personally, I like my propellers to turn outwards to keep the camera clean. Yes, that means the FC and ESC are always dirty. But when the propellers point inwards, there is more dirt on the camera.
Whichever style you prefer, let's get to the ESCs!
ESCs can be purchased in a range of setups, but the choice should be simple.
Single ESCs - The single ESC is connected to a single motor. All ESCs are connected to a separate PDB (Power Distribution Board), which in turn is connected to the FC.
Advantages:
Disadvantages:
4in1 ESC - 4 ESCs and a built-in PDB are all together in one board which saves the time and labor needed to assemble the drone. However, this also has a disadvantage because if one ESC fails, you have to replace the entire board.
Advantages:
Disadvantages:
AIO boards (FC+PDB+ESC) - These are all-in-one boards where everything works right out of the box.
Advantages:
Disadvantages:
Using a high-quality ESC will ensure a smooth and balanced flight and keep your drone in the air for a long time. Poor quality ESCs can have problems and burn out.
IMPORTANT NOTE: Always use a smokestopper before plugging in your ESC for the first time.
IMPORTANT NOTE 2: Always cover the electronics of the regulator with insulating tape when soldering. Those nasty, wild solder balls can cause a short circuit that is hard to detect!
But how do you choose the right ESC?
First of all: the size. 4in1 ESCs (and AIO boards) usually come in 30x30 or 20x20. Once you know what size you need for your drone (see our blog post about frames), there are a few things to look out for:
check the current rating, which is measured in amperes (also known as "amperage").
The amperage rating is the limit of how many amps you can put on a regulator without it bursting into flames, not how much current it delivers to the motors (so it can only be too low, but never too high). 3 things can increase your current draw:
As a rule, the controller has 2 current levels: Continuous current and pulse current (higher current that lasts for a few seconds). For 5" drones, we usually recommend 45A and above.
So is it better to buy a bigger ESC? Because of the current surges and voltage spikes? Some people prefer larger ESCs because of the voltage spikes, which are much higher than the battery voltage. However, this is a matter of taste.
BLHeli_S ESC uses 8-bit processors, while BLHeli_32 uses 32-bit processors. 32-bit processors are certainly more powerful and enable many new functions that were not possible with the 8-bit versions. The 32-bit ESCs allow us to have programmable LEDs, higher PWM frequencies, telemetry and many other features. The 8-bit versions are still available and popular (mainly because of the lower cost), although they take away the ability to use speed filters (which allow for smoother flight).
Just like FCs, ESCs also have their firmware - but unfortunately the two often don't go together. The most popular FC firmware is BLHeli, which is usually paired with BetaFlight. But the FC and ESC firmware can be mixed and matched to suit different needs. You can even use a Fettec ESC with a FlightOne FC board. Everything is possible.
The most popular firmware:
SimonK and BLHeli:
SimonK and BLHeli are two of the oldest open source firmwares for controllers. Early ESCs are still written with primitive firmware from manufacturers, but it is easy to flash them with 3rd party firmware for better performance. Later BLHeli became the FPV industry standard and almost all ESCs have it pre-installed. SimonK has since become obsolete and is no longer updated.
BLHeli_S
BlHeli_S is the 2nd generation of the BLHeli firmware, which was specially developed for ESCs with "Busybee" processors (mostly small drones).
BLHeli_32
The BLHeli_32 ESC firmware is the 3rd generation of BLHeli. Specially written for 32-bit ESCs. However, this is a closed source! The more powerful processors allow for better future development and smoother, more precise and reliable performance than previous ESCs.
Which ESC firmware should you install on your ESC? It depends on the processor. Most ESCs come pre-installed with BlHeli, and they are great. Just update them.
Fettec
Fettec has developed its own software set for its special ESCs. This means that there is a different setup for their AIO board and their ESCs. This firmware enables ESC + FC pairing which allows a lot of additional options.
KISS
Since Kiss and Fettec are connected... yes, Kiss also has their own firmware in their ESCs that allows pairing with the FCs and expands the compatibility and possibilities of the stack.
Proprietary firmware from another manufacturer
Some advanced ESC setups (not typically used for FPV drones) have their own ESC firmware set by the manufacturer, but since we're on the FPV topic... let's skip that.
You've probably seen a setting that requires an ESC protocol. Think of protocols as a kind of "language" that FC and ESC use to communicate. One of the basic tasks here is to communicate how fast the motor should turn. The ESC protocols currently available on the market for FPV drones are compared below based on their signal width. The signal width is the time it takes to send a data packet.
You may be wondering what PWM is - this is the standard protocol that was available on all ESCs prior to 2015. As you might imagine, as the hardware improved, faster protocols became possible. Faster protocols are synchronized with the PID loop to reduce judder and improve overall performance. DShot is the latest ESC protocol, which is a digital signal. Most ESCs are now equipped with it.
We hope you enjoyed this blog post. Let us know what you'd like to learn more about next on Instagram!
See you next time!
Your Lexie
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