Apr 132012
 April 13, 2012  Posted by  Add comments

Wiring Layout

How to wire a quadcopter is often assumed to be common knowledge, but when I started to build my quadcopter a few months ago I knew virtually nothing about rc wiring or electricity and had to search around a lot to figure it out. This post is an effort to describe what I have learned and how I wire my quadcopters.

There are lots of good wiring diagrams on the net, but sometimes they can be confusing to read, so I took this picture to describe how I wire my quadcopters:

Quadcopter Wiring

Quadcopter Wiring

Continue reading to see my explanation of the above wiring layout…

* For simplicity, I have only shown two ESCs and motors in the picture above, but on my quad, all four of them would be connected.

  • The ESCs are connected to the battery in parallel via a wiring harness.
  • The other side of the ESCs are connected to the four motors.
  • Each ESC’s BEC (battery elimination curcuit) is connected to the appropriate motor pins on the flight control board.
  • Connections are made from the flight control board to the receiver for power, pitch, roll, throttle, yaw, etc.
  • To monitor the charge level of my battery I connect a little monitor/alarm directly to the battery’s balanced charge connector

Battery Connectors

I connect my batteries to my wiring harness using an EC5 connectors. Some folks prefer using Deans and XT60 connectors, but I like the EC5s because they are big and easy to solder. To use them, I had to replace the existing battery connectors. When soldering on the new connectors, I was careful to only cut off and work with one battery wire at a time to avoid the two wires ever touching and getting a shock.

Wiring Harnesses

A wiring harness is used to connect the battery to the ESCs. There are lots of different wiring harness ideas for quadcopters. Some people use power distribution boards that allow ESCs and batteries to be plugged in directly. This seems like a very elegant solution, but the board has to be connected to your frame and might be unwieldy. Other folks build or buy custom harnesses. Here is a video on how to build a spider harness and here is another good video on building a custom quadcopter harness.

Wiring Harness

Wiring Harness

I built my wiring harness to connect to the 8 ESC wires on my quadcopter to the battery in parallel. I ended up using 18 AWG wire for my harness because it was readily available. Each of the motors in this setup pulls a maximum of 10 amps and I use 18 amp ESCs. Larger motors and bigger ESCs may require higher diameter wire. Perhaps, these should be a higher diameter, but I haven’t noticed any problems and the 4 wires fit well into the EC5 connectors I use in my harness.

I made my harness using:

  • 8 – 18 AWG wires, 4 red and 4 black.
  • A male EC5 connector (two large male bullet connectors and a plastic casing) on the battery side.
  • 8 – 3.5mm bullet connectors on the ESC side.
  • Solder
  • Heat shrink tubing to cover exposed wires and connectors.

ESC Connectors

ESC battery and motors wires usually don’t come with connectors. I solder 3.5mm male bullet connectors to the battery side of my ESCs and female 3.5mm bullet connectors to the motor side of my ESCs.

Red battery and harness wires must be connected to the red (+) ESC power wires. Black battery and harness wires must be connected to the black (-) ESC ground wires. Not doing so can destroy the ESC, cause a fire or shock.

The three wires on the motor side of the ESC can be connected in any order. Reversing any two of the three motor wires will cause the direction the propeller spins to reverse.

The ESC BEC has a standard 3 wire servo type connector that is used to power and communicate with the flight control board.

Motor Connectors

Motors often come with male 3.5mm bullet connectors already soldered on. If not, I solder them on and add heat shrink.

Control Board and Receiver Connections

Tip - Power and Signal Wires Tip – Power and Signal Wires
Determining which pins to connect power and signal wires to can be tricky and care should be taken to avoid a short. Many boards and receivers will have labels like +, G, and S. On others it is necessary to consult the manual or find a forum where someone has figured it out.

ESC BECs have three wires, a signal (usually white or orange), a power(usually red), and a ground(usually black or brown). The power wire typically delivers 3 amps of power that can be used to power the flight controller. Most flight control board manufacturers suggest that only one BEC power wire is connected. This can be done by removing the power and ground wires from all but one BEC or removing just the power wire from three of the four BECs. The signal wire must be connected for all four ESC BECs to transmit motor speed commands to the ESC from the flight control board. Here is an excellent post on the OpenPilot forum that discusses all the options.

Custom receiver connectors usually come with the flight control board and provide power to the receiver from the board and have signal wire connector(s) for pitch, roll, throttle, yaw, camera control, etc. A Pulse Position Modulation (PPM) TX/RX  may only need 3 wires for power, ground and signal. With PPM all the signals are sent over one wire. A Pulse Width Modulation (PWM) TX/RX uses separate wires for each signal.

Wire Gauge

American Wire Gauge (AWG) is a standardized wire gauge system based on the diameter of the wire. The diameter of the the wire chosen for rc models is important. Wider diameter wires can handle more current. Unfortunately, I have found that the high strand count, flexible silicon wire that is best for rc applications, is not always available in all AWG diameters. Also, many of the components I buy use different wire gauges. Ideally, I would try to use the appropriate wire diameter throughout my quadcopter based on the maximum amps traveling through the wires. Here is a post from rcgroups that has some suggestions on proper wire sizes.

Soldering Connectors

Unless you plan on buying a bunch of pre-soldered harnesses, motors and ESCs, it is necessary to learn some basic soldering skills to build a diy quadcopter. I don’t have very good eyesight or dexterity, so, if I can do it, anyone can.



I use two types of connectors in all my quadcopters. EC5 connectors to connect my batteries and 3.5mm bullet connectors for everything else. The EC5 is large and can easily hold 4 positive and 4 negative wires coming from the ESCs.

Soldering connectors to wires requires:

  • Soldering wire that includes flux. Flux helps the solder flow.
  • A soldering iron.

I bought a big spool of solder from Radio Shack. Harbor Freight and WalMart are great places to buy a cheap soldering iron. I have a 30 watt soldering iron from Harbor Freight. It only cost a few bucks and works great.

It helps to:

  • “Tin” the tip of the soldering iron (coat it with a little bit of solder).
  • Have a good clamp or jig to hold the work.
  • Have clean soldering surfaces.

To solder together wire and bullet connectors I follow these steps…

  1. Strip the wire back to the same as the depth of the bullet connector.
  2. Tin the wire, which means filling and coating the end of the wire with solder
  3. Heat the bullet connector.
  4. Partially fill the bullet connector with solder (too much and it will spill over the side).
  5. Place the wire into the connector partially filled with hot solder.
  6. Hold the wire straight until the solder hardens.

Here is a good video on how to tin wires and solder EC5 type bullet connectors. Here is another video that uses a wood holder to solder 3.5mm bullet connectors.

Tip - Heat Shrink Tubing Tip – Heat Shrink Tubing
To insulate, protect and avoid shorts I always place the appropriate size heat shrink tubing around the wires and above my solder joint before soldering on a connector. After the solder cools, I slide the heat shrink tubing over any bare wire and exposed connector. Finally, I shrink it down with a torch or heat gun.


Once all of the soldering is done, I connect all the parts to my frame always making sure red is connected to red and black is connected to black to avoid shorting something out.

That is how I do my wiring. It may not be perfect, but hopefully it helps someone. Of course, just because I did it this way doesn’t mean it is necessarily the right way or the only way, but it works for me. Remember that these are not toys (well, they kinda are) and dealing with electricity can be dangerous.


  30 Responses to “Quadcopter Wiring”

  1. this photo of the wiring greatly helped me. I am going to now order the parts for making my first quad copter with a bit more assurance I can finish it. I especially liked the photo of the connectors. I am assuming that a copter for 6 and eight motors are similar.

    could you elaborate on where to put optional equipment?

  2. Hey britt,plz suggest me flight control board having price under $20..i dont want to use k2.2…i want to code it by myself!
    thank you!

  3. Is there a way to use a working commercial quadcopter controller/ESCs and change the driver of the motors to be able to use bigger motors? I was thinking about using circuitry containing MOSFETS in series with the power leads of the motor so that it can drive a bigger motor with the same ESC. (Something akin to a power amplifier.) In that way, you can use many of the old (and proven) components, (and the TX/RX ) when you want to build a bigger one.

  4. Hi, can somebody help me to understand what is the meaning of cont.Current and the MaxCurrent of this calculator for quad? http://www.ecalc.ch/xcoptercalc.htm?ecalc&lang=en, is it the esc current found in its specs?

    thanks for the help guys.

  5. Hey, I’m building a quadcopter and was looking at 4mm to 4×3.5mm bullet harness to wire the esc’s to the battery. Would I be ahead to get a harness for a hexacopter that has 4mm to 6×3.5mm in case I want to add LED’s or something later on? Basically only use four of the connections and have two extra for powering other things, or would there be a better way to do it?

    • The wires and connectors on the harness are designed to power ESCs. Usually the LEDs use smaller wires and connectors. Also, the voltage for the LEDs need to match the battery voltage if you are tapping directly into the battery power. I have never added LEDs to a quad, but I don’t think that is how I would do it.

    • I have seen them but never tried them. I was worried if one ESC went bad the whole thing would be unusable, but it seems like they would be worth a try and help to make a clean and simple build.

  6. http://www.seeedstudio.com/recipe/index.php?controller=recipe&action=show&recipe_id=14&AllStep=1
    great guide for a beginner, I think this will be the solution if it hasn’t connectors.
    Take a look at it.

  7. the KK 2.0, the one you recommended me, does it have the connectors?
    I dont think the motor and Esc’s are a problem, only the little computerchip.

  8. Hi,

    Does the flight controller must be soldered or can you easily plug it in with connectors?
    I know the wires need to and that is not a problem.


    • Some require soldering, but most have the headers already soldered on so you can plug the connectors in. Also, unless you buy a harness, escs and motors with bullet connectors already soldered on, you will have to solder on the bullet connectors yourself.

  9. Might be a dumb question, but how do you know which of the motor’s three wires go to the ESC’s three wires? My ESC’s wires are labed A, B, C, but the motor’s wires are not labeled at all. Thanks!

    • I just connect them in any order, then if the motor spins in the wrong direction, I switch any two of them. I’m prretty sure this is the standard approach.

  10. Hi…

    How you connect the battery (11v) on the control board if this input voltage is 4-6v???
    same situation to RX module or other accesories that input are less then 11v or 12v…


    • What board are you using? Different flight control boards are powered different ways. Many are powered by one of the power wires from one of the ESC BECs. Many ESCs have 5v BECs. Other boards get power from the battery and have their own voltage regulators. You should read the documentation for the specific board you are using to figure it out. Also, most flight control boards have RX headers that power the RX through one channel that I believe is 5V, but I really don’t know. I have always just plugged my receiver in and it worked. Definitely read all you can about the board you are using before attempting to power it or connecting a receiver to it.

      • Thanks Britt.

        My dounbt is because my order didn´t arrived yet, and then I want to know if I need to buy someone else.

        I Bought the ESC 30A HobbyKing and the KK2.0 (LCD) Control Board.

        The TX and RX, I intend to buy the Turnigy 9X…

        So… you mean that ESC “gives” the power to the board, and when I plug my RX on the board, automaticaly it is powered by the control board?

        Please, correct me if I’m wrong.

        Thank you for you help!

        • Yeah, each ESC has a BEC (battery elimination circuit) that is plugged into the KK2.0 board. On some boards it is better to connect just 1 of the 4 ESC BECs to provide power. But, the KK2.0 only takes power from one of the ESC BECs regardless of how many are connected. That is good. Otherwise, you would have to disconnect all but one ESC BEC power wire.

          I only connect one power wire coming from the KK2.0 board to my receiver.

          You might be able to see in the picture below how all of the ESC BEC wires are connected on the right, but only one power and ground are connected to the RX on the left.


  11. I’m looking foward for to build my own quadcopter prototype, and i was wondering which board to use… I’d like a cheap and tiny one, to whom connect(or better if already on it) gyros and a radio transmitter. How’s the one that’s in the picture? I’m a little noob on this topic… Anyway, your guide is very helpfull, thx a lot.

  12. Here’s a tip for quickly and easily soldering bullet connectors:

    You’ll need a mini butane torch with a pencil flame, and a “3rd Hand” with the small alligator clips.

    1. Tin the wires that you plan to solder to the bullet connectors with a regular soldering iron.
    2. Clip one half of the bullet connector in the 3rd hand, and heat it with the butane torch. As you heat it, feed solder into the hot bullet connector until its 1/2 to 3/4 full.
    3. While the bullet connector is still hot and the solder still molten, insert the tinned wire into the back of the connector and hold it there until it cools.

    The entire process should take about 20 seconds per connector. Super easy, clean, and quick! The same process can be used to desolder them, just in reverse! Heat with torch and tug on wire to remove it from the connector!

    Hope this helps!

  13. My buddy and I just built our first quads from scratch. I told him the longest task was soldering all the bullets…afterwards he said “I used to like soldering…not anymore!”. LOL

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