I came up with some ESCs having BEC and some don't. So I would like to know actually what is BEC. What does it work?
P.S. I am newbie, help me pls 😊
Thanks in advance.
Regards

BEC stands for Battery elminator circuit
It converts the lipo voltage to around 5 volts...This 5 volt powers ur receiver and servos
so if ur Esc dosnt have a BEC u will have to add an external one

So I must need it for every motor? I am using Sunnysky 2212-980kv motor and Pixhawk

Most esc have an bec built in .but your pixhack would be better powered with its voltage current sensor.

BEC is battery eliminating circuit.
Your receiver need supply so BEC provides 5v from ESC's supply by means of a regulator.If your ESC has BEC then you need to connect it to receiver by only one BEC supply. Do not connect many BEC's red wire to receiver there is chance of flowing circulating currents.Just remove that red wire connection from all except one. If your ESC dont have a BEC connect it receiver directly.There's no problem at all.
You may see few ESC's dont have BEC because these ESC's are high voltage ESC's supporting 22v so bringing 22v down to 5v through a linear regulator dissipated lots of heat so they don't have one inbuilt into it.

But My receiver have PPM output , and it will go to Pixhawk flight controllers and not to motors directly.

your receiver will send the signal to pixhawk.....then pixhawk will do the calculations and send the signals to ESC....as to how fast or slow the motors would spin

just a suggestion .... this is ur first multirotor build....better go with kk 2.xx   Flight controller  ....

multirotors are serious machines....if you can read between the lines....you should do a lot of research before buying/building a multi...



this forum is full of helpful people....and we will try our best to help ....but you would have to take some effort to learn ......and guess what....most of these things are explained in a very detailed fashion on youtube

please take some time to learn via vids/blogs/websites....

the quadcopter is something like this:
1. radio reciver, function: to take the input from the user and do accordingly
**in the case of a multi rotor, The input from the reciver goes to the flight controller.
2. flight controller,function: provides GYROS for a stable flight, u can get additional features like GPS and other added functionalities
**The flight controller is required by every multirotor and they have 6-8 set of pins to which u will connect your ESC's to, THE ESC IS NOT DIRECTLY CONNECTED TO THE RECIVER
3.ESC, functon: controls your brushless motors, has approximately 8 wires, 2 connect to your main battery (through a PDB or something like that), from the same end as the power in, 3 wires will come out that are not THIN and have an adapter at the end of it,, this goes to  your flight controller, on the other side of the ESC you will see 3 THICK wires, one to extreme left, middle and Extreme right, this will connect to your Brushless motors.NOTE the direction in which the motors turn, the front left and the back right motors should turn clockwise and the other two anti-clockwise, Same goes for props!
if the motor is not spinning in the direction it has to, simply switch 2 leads (It doesnt depend on the ESC or the motors, that technique is used by EVERYONE)! just dont make the wire leading to the brushless motors touch each other when they are active, use heatshrink tubes to cover the bullet connectors so they wont touch mid flight!
The circuit goes like:
RECIVER->FLIGHT CONTROLLER->ESC->MOTOR

if u fell that u didnt understand what ever i have blabbered, then i guess you should just watch some build videos that are online! or pop a question on this website! everyone is ready to help

Thanks a lot for your replies.
 I am pretty good at software. The reason I choose Pixhawk is because of its serial bus. I want to connect my Intel Edison to Pixhawk and communicate them via a serial bus. It's not like my hobby (but I like it so much and became my hobby now :p), I am doing this for my project. Receiver send PPM (Pulse position modulation) to Pixhawk and then Pixhawk do some calculations by taking some input from gyro and sensors to stabilise the multi rotor. Since I saw BEC a new concept that I didn't knew, I asked you!! Okay, so receiver needs BEC to get correct voltage, but my receiver will have voltage and power from Pixhawk which is operated at the same voltage. Still do I need to install a BEC in between Pixhawk and receiver? Since I am doing a hexacopter, do I need ESCs having BEC? ESCs are connected to Pixhawk and motors and battery.

ESC's having BEC shouldnt matter, u can have all ESC having BEC or u can power the Pixhawk externally, all that matters is the signal wire from the ESC!
Ur Pixhawk will provide enough voltage to run the receiver so even if you do not have a BEC with the ESC, u need to supply 5v to the Pixhawk externally and everything should run smooth! u can provide 5v to the Pixhawk by just plugging the external BEC plug beside any ESC signal wire!

BEC is battery eliminator circuit.

It is required because some components (FC, Rx) use 5V and batteries are usually 11.1V or higher.

To power your Pixahawk, either power it through ESC with 5V BEC or use a power module (recommended).

If powering through ESC, check what kind of BEC your ESC has. If it is Linear BEC, you can connect all ESC servo pins to the Pixahawk. If it is a switching type ESC, then you need to remove the red wire from 3 of your ESCs and only keep it in 1.

Exactly!! That's what I am doing! I have external XT60 power connector that comes with Pixhawk which goes in dedicated power line. Thanks man!! 😊😊

I have external power connector for Pixhawk.. So even if I bought ESCs with BEC I will remove the red wire from that 3 pin connector, thanks man!! ☺️