Powering your flight controller is an important aspect when it comes to building your own drone, if you get this wrong you might experience some release sparky the blue smoke monster.. Or worse you could end up having a power failure mid flight, damaging more than just your flight controller. In this guide I will […]
Powering your flight controller is an important aspect when it comes to building your own drone, if you get this wrong you might experience some release sparky the blue smoke monster.. Or worse you could end up having a power failure mid flight, damaging more than just your flight controller. In this guide I will discuss some things to think about when it comes to powering your flight controller.
There are several methods you can consider when it comes to powering your flight controller which are each discussed in more detail below:
This would seem like the most obvious method for powering your flight controller, however there are actually very few flight controllers on the market today that you can power directly with your battery.
In general its safe to assume that you cannot power your flight controller directly from your battery
Most electronic devices run on either 5V or 3.3V, and a typical battery you would use on your drone would be at least 11.1V. Check out or LiPo Battery guide for more info about batteries. Although a flight controller can be designed to have a built in voltage regulator, having a regulator step down such a high voltage often introduces extra heat, or other electromagnetic interference which can cause issues with some of the sensors on your autopilot such as the compass sensor. So its often better to keep this off the autopilot board to improve performance. Always check your documentation or the actual flight controller PCB (printed circuit board) to ensure you feed it with the correct voltage. Using a higher voltage will fry your board.
Perhaps one of the more common methods for powering flight controllers, particularly on simpler quadcopter builds to directly via your ESC as most ESC’s include a built in voltage regulator (known as a BEC) to provide a constant 5V output. However there are a few things to consider if you plan to power your flight controller via your ESC. Almost all flight controllers can be powered via your ESC, but there are a few special outliers that cannot so its a good idea to check the documentation of your flight controller.
If you dont know what an ESC is, then its a good idea to check out our ESC guide for more details on what an ESC is, and what it does.
Also known in this hobby as a BEC, a voltage regulator will convert your battery voltage down to a clean and constant 5V to supply power to your flight controller. There is no difference between a BEC and a voltage regulator As discussed many moderns multi-rotor ESC’s dont have any voltage regulator so you often need to use a separate BEC to power your flight controller. However this is not realy a bad thing thing since with most FPV drones you will need to power your FPV camera and transmitter with a separate power source anyway. Again you have a few options when it comes to powering your flight controller via a voltage regulator.
Many of the full autopilot systems such as Pixhawk, come with a dedicated power module. In addition to providing a clean 5V power supply for your flight controller a power module often includes a few extra electronics to include a current and voltage sensor. These are particularly useful since it allows your autopilot to monitor your battery so it knows how much power it has left. Many autopilots such as the Pixhawk have a failsafe built in that will land or return home to the takeoff location if it detects that the battery capacity is low.
A power module will often connect directly to your battery and its output would go onto connect with your power distribution board. Because a power module will measure the battery current its important that you connect it the correct way around as the current needs to flow through the power module in a specific way.
Check the current
Because all the power routes through the power module, all the electricity that goes to the motors will need to pass through the power module. So if you are using lots of motors (hexacopter) or very large motors you need to ensure your power module will be able to handle the current, otherwise you can burn out your power module. The default pixhawk power module can handle 90A. To learn more about current draw on your drone check out our guide on choosing multicopter motors.
Now that you know the basics of powering any flight controller one of the last things you should check is the polarity. What I mean by this is that you make sure to connect the positive voltage wire (often red) onto the positive pin on your flight controller, and the ground wire (often black) to the ground pin on your controller. Although many boards have reverse polarity protection, not all of them do and if you connect power the wrong way around you can fry your board, and also void any warranty.
The same applies for voltages, every electronic device is rated to work with a certain range of voltages, for example most miniquad ESC’s work with 3S or 4S LiPo batteries, so its important to make sure that you dont connect a battery that has a higher voltage than what your ESC / voltage regulator / power module can handle. As an example of this, look at the image of an ESC that I soldered the wrong way around on my PDB, it ended up completely melting a wire!
So thats it, hope this guide has helped you learn abit more about the drone hobby and that you will never have any issues powering your flight controller. If you have any questions, suggestions or storied of you burning something up, just share it in the comments below.