Power Distribution Boards - How to choose the right one

multirotor

#1

In this guide we will discuss everything there is to do with power distribution boards (or PDB for short), what they do, how they work and how to go about choosing one for your multirotor drone build.

What is a Power Distribution Board?

PDB’s are often an overlooked area of multirotor drone building, mainly because they are fairly simple but despite this they are a crucial part of your drone and if you don’t choose the right one you could end up loosing your drone.

As the name suggests, a PDB distribute the power on your drone, and provides a neat and tidy way of connecting your battery to all of your ESC’s on your aircraft. A PDB has positive pads/terminals which are all connected and negative terminals/pads which are all connected. This way when you solder all of the red wires from your ESC’s and battery to the positive pads on the PDB, and the black wires to all the negative pads, they will all become connected so your battery can provide power to all of your ESC’s as shown in the image below.

Stand alone or integrated PDB
Some multirotor frames has a power distribution board integrated into the frame, allowing you to solder the battery and ESC connectors directly onto the main frame of your drone which is very convenient. Integrated PDB boards can only be used with fibreglass plates, as carbon fiber conducts electricity, making it impossible to have a carbon fiber PDB. For this reason all carbon fiber quadcopters have a separate power distribution board which you mount onto your multirotor frame.

How Does it Work?

There is not much to a PDB as its simply a basic circuit board that connects all the ground connectors to one another and all the positive connectors together allowing you to power all of the equipment on your drone in a neat and easy manner instead of having a birds nest of power cables going between all your gear.

Voltage Regulator

Some PDB boards aso include a voltage regulator, also known as a BEC. A voltage regulator is a small circuit that regulates the voltage to a specific value, commonly 5V, or 12V. So if you are using a 4S LiPo battery (which is 14.8V) the voltage regulator will convert that voltage and output a constant 12V, or 5V that you can use to power certain equipment such as LED lights, or FPV equipment which is a very usefull feature as not all equipment on your drone will be able to work on 14.8V. The PDB that is shown below includes two voltage regulating circuits, one of them provides a constant 12V output, while the others is adjustable to whatever voltage you require.

How to choose a Power Distribution Board

There are three main factors to consider when it comes to choosing a PDB for your drone. Even though some multirotor frame kits include a PDB, or have one integrated inside one of hte frame plates its still a good idea to check the specs to ensure it will work with your motors/ESC.

Current Rating
The main safety aspect in terms of choosing a PDB for your drone is to make sure the PDB can handle the amount of current that is required to pass though it. The way to work this out is fairly easy, you simply need to check the ratings of your ESC’s on your multicopter to find the maximum total current draw. So if we are building a quadcopter that uses 4x 20A ESC’s we ideally need to have a PDB that can handle (4x20A) 80A. However in reality we will not be flying our quadcopter at max throttle so you could get away with a 60A PDB, but in my opinion its always best to spend abit more and use a over rated PDB as its worth the extra safety factor.

Number of connectors
A fairly obvious thing to consider is to make sure the PDB has sufficient connectors for all of your ESC’s so you can easily solder everything to your board.

Voltage Regulator
As mentioned before having a voltage regulator onboard the PDB provides a convenient way to power auxiliary equipment on your multirotor drone such as external LED’s or FPV equipment.

So now that you know the basics of what a PDB is, hopeful you will be able to be better informed when it comes to choosing a PDB for your next multirotor drone build. If you ever have any questions, or comments just add them below.

Where to buy a PDB?

We sell a range of power distribution boards at our shop. If you have any questions please let me know and I will be happy to help.


What to consider when buying a ESC for your multirotor
#2

Excellent write up. Link to online store pdb’s however doesn’t give their rated amperage so no informed choice can be made using advice taken from the article. Don’t take me the wrong way, I know a lot more about stuff after reading than I did before, and my thanks are here.

I am building a diy project from barebones using a Hero 550 quadcopter frame. I tentatively need (x4) 4008 Outrunner brushless motors with 40A ESC’s and I presume upstream of the supply line input to Pixhawk v2.1 FC a 40A BEC ESC itself run directly off the power supply (2S-6S LiPO), therewith isolated ESC line-out assignment on dedicated ESC channel via a PDB.

Am I close?

Further question: do I need ESC’s for the Retractable skids servos, 3-Axis camera Gimbal servo, Holybro Telemetry thinggy… …Lidar avionics/proximity sensor… FPV… (I hope the Pixhawk+cube v2.1 knows what I’m doing).

…I’m out of breath, and now the world grows dark: beyond here there be dragons.


#3

Typically for that you will need a relatively high current PDB, but if you look at your motor thrust tables you will see that the hover thrust is not at 40A, and will probably be considerably lower so you can choose your PDB based on that value as most PDB boards have a continuous current rating, and then a burst current which is higher but only for short periods of time.

Also the pixhawk uses a separate power module which is connected directly to the battery so more important to the PDB is to figure out the current draw of your entire drone to make sure you choose the correct battery and also make sure the total current draw of your drone is not higher than that supplied by the power module/ BEC.