Tag Archives: esc

Is ESC without BEC an OPTO ESC – some quick explanation

I will try to keep it super simple (KISS) and explain why an ESC without BEC is not necessary an OPTO ESC. BEC stays for battery eliminator circuit. It is an electronic circuit, which delivers power to other electronics, like your flight controller or receiver. That is why we connect the red wire of the servo cable to the FC, it simply outputs (hopefully stable) 5V.

Some ESCs don’t have an integrated BEC and can not supply power for your controller or receiver (for example: KISS ESCs, Afro Race Mini 20A or XRotor 15A). In this case you need a separate BEC for powering them. There are also power distribution boards with integrated BEC. I personally use the ACSP3 from Nick Arsov.

So far so good. The problem is many ESCs retailers and manufactures (mostly Chinese) don’t know, that an OPTO ESCs is just not equal to ESC without BEC. OPTO means that the ESC have an opto-isolator. If you Google it, you will find that, it is a optical component that transfers the signals between two isolated circuits by using light. The main purpose is to prevent rapidly changing voltages or high voltages on one side of a circuit from distorting transmissions or damaging components, like the receiver, on the other side of the circuit.

I have never experienced any problems with my not OPTO isolated ESCs, but thought it is good to know what an OPTO ESCs really means.

HobbyWing XRotor 10A ESC

Some time ago I looked for small, quality and not expensive ESC for my SG Acro quadcopter and I found the HobbyWing XRotor 10A. Ordered four of these and approximately 2 weeks later they are by me. I don’t have a free acro frame now, to mount them on, so the flight test will be in a few weeks. But as I love to take pictures, here are some of the ESCs:

They came well packaged, but with manual in Chinese. This is actually normal as I ordered the Asia-Version, because it was cheaper. If I wish, I can always download the English manual.


The ESC is really small: 36.5mm x 16.4mm x 4.1mm. The weight is 6.5g with 2mm connectors already soldered. So it is really easy to connect to my T-Motor MN2206 or MN1804 motors. It is important to know, that the ESC does not have any BEC, so you cant power the flight controller directly from the ESC.


I decided to remove the heat shrink on one of the ESCs, to check what is inside and as expected, these ESCs are exactly the same as the T-Motor Air 10A. I have already tested one T-Motor Air 10A (compared with one HK BlueSeries 12A flashed with the newest SimonK and comp_pwm enabled) and it performed great. I am not absolutely 100% sure if the XRotor 10A have the same firmware as the T-Motor Air 10A, but it is probably the case.

HobbyWing XRotor 10A:



T-Motor Air 10A:



Both ESCs are labeled as 2-3S, but I will give it a try on a 4S configuration and see if it will burn. If you already tested these ESCs on your multicopter, I would love to know about your flight experience with them.

Power distribution board vs. Cable harness

When I started with the Multicopters in the late 2012, I used cable harness/power breakout cable  for the power distribution from the battery to the ESCs in my first quadrocopter. Until last month I always used my self-made cable harness in my copters. There were no problems during the flights and everything was just great.

Last month I decided to buy one from these so called power distribution boards. Just because of the weight and it looks a bit better when there are not so many cables. My goal was to safe some grams and optimize the overall weight of my SG Adventure quadcopter. It is a small quad and every gram matters.

Soldering was a bit tricky, because I left the ESCs mounted on the quad and I am not so good at soldering. In general there is no difference, but it looks better for me now. The quadcopter flies great, as it was with the cable harness.

How many grams do I saved?

Cable harness and the 3.5mm gold connectors, that I cut from the ESCs wires: 28g + 12g = 40g.       Power distribution board + 4mm gold connectors to the battery + some tin-alloy: 3.5g + 10g = about 15g. So I saved about 25g, which is not much, but for small copters every saved gram means more flight time.

Another cool feature on this flyingfolk board is, that it is possible to solder other low current components such as LED or Voltage-Sensor on the corners.