ESC for EMAX RS2205 2300kv BLDC

Hey guys!

Complete and utter noob here. I am looking for a suitable ESC for the EMAX RS2205 2300kv BLDC mounted on a Martian II 220mm frame. I already have a Pixhawk PX4 2.4.7 and plan on using that. I will be using the drone for indoor videos and/ or target tracking.

I had shortlisted the Emax BLHeli Series 30A ESC, but saw a lot of people posting about issues with it(esp. on YouTube). As of now, i need a solution which works out of the box and want to avoid the nitty-gritty of the firmware etc.(I also read that EMAX ESCs may face issues with the Pixhawk FC)

I would be immensely helpful if someone could suggest a suitable ESC which comes with the firmware pre-flashed.

Here are a few which i had shortlisted(based on motor ratings and referred this link:

1. Emax BLHeli Series 30A ESC(
2. Emax Bullet Series 35A ESC(
3. Spedix IS30 ESC(
4. Racerstar RS30A V2(
5. Holybro Tekko32 35A(
6. Aikon AK32 35A ESC(

I would be grateful for any help I receive.

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  • Not sure you would go wrong with any of those choices. Best advise I could give is stop reading posts about issues or watching YouTube gripes. In nearly all cases the user is the problem, not the hardware. At KwF we exclusively use Favourite ESCs on small aircraft. Authentic Favourite ESCs are made very well. Other manufacturers sometimes use less reliable hardware. On such a small aircraft, you might want to use a 4-in-1 ESC. These also work great and save space & mass.

    We purchase just about every ESC on the market for testing, and we have never found one that arrived without firmware pre-flashed. Sometimes the firmware is not current, and sometimes the default parameters are not desired; so we reflash, set parameters, and lock out RC programming.

    When we teach robotics to small children, we provide ESCs that are locked down on firmware and all parameters except throttle calibration -- usually Simon-K firmware.

    I would worry more about that Pixhawk 2.4.7. It is a rather old flight controller with very limited performance.


    CTO, Kashmir-Robotics
    • I can also only join. Most of the time it is really the use and only in a few serious cases the device itself. On the other hand, you can be happy about it, because it can also be expensive.
    • Thank you, Ron!
      As i understand from your comment, any of the above mentioned ESCs should be fine for my drone.

      Could you please elaborate on why you have concerns about the Pixhawk?

      Some people have reported that EMAX ESCs have trouble with the Pixhawk, for eg. according to this thread(;

      "I did some digging and came across a few threads of people claiming that EMAX ESCs will not work with Pixhawk because the voltage on the servo rail is 3.3v instead of 5 and the ESC draw pulls that down to 2.8v or 2.2v I don't know how accurate that is, but I was hoping somebody on these forums might have found a work around and/or possibly run into it and discovered they were just overlooking something."

      Is that a cause for concern??

      Thanks again.
      FliteTest Forum
      Welcome to the Flite Test Forums!
      • Let me repeat that the best advise I could give is stop reading posts about issues or watching YouTube gripes. EMAX ESCs are fully compatible with Pixhawk 2.4.7 and with all Pixhawk variants. If you like or have EMAX ESCs, use them. Some small ESCs come with an integral Battery Elimination Circuit (BEC) to provide ~5.5V to the output rail. Most multicopter ESCs do not, If you need voltage on the output rail, and your ESCs do not have BECs, then simply add a small 5.5V BEC to your rail. This is your first aircraft, and it will fly just fine with EMAX ESCs and Pixhawk 2.4.7.

        At KwF we have complex test equipment to help select the best components, but with ESCs I usually tell people to just hold them between your fingers during full throttle for 10 seconds. Some will get so hot they will burn your fingers. Some will just be a little warm. Those are the most efficient. Then weigh them; the least weight is the best.

        I was never a fan of the Pixhawk 2.4.7 because the designers made poor choices for connectors. They fail with wires pulling out of the connectors, connectors pulling out of their slots, and internal board mechanical failures. If you have one and need to save money use what you have. If you can afford a new fight controller try the inexpensive Pixracer, either from mRobotics or other manufacturers including the Pixracer R15. All provide improved performance over the Pixhawk 2.4.7 and feature better cables and connectors.

        CTO, Kashmir-Robotics
        • I took a quick look at the Flitetest forum. The posters attributed failures to hardware that were their failures to understand their hardware and firmware. For example the poster about Pixhawk 2.4.7 rail voltage did not have a clue as to what sets the voltage on the rail of a flight controller. Also the poster about the Pixhawk 2.4.7 not initializing the ESC did not have a clue as to how to initialize an ESC. These are parameters set in the ESC firmware and the Flight Controller parameters. Set them correctly and the ESCs will initialize correctly. In building your first aircraft, ask knowledgeable people for assistance when something does not work as expected. Most all commercial hardware works when operated properly.
          • Hey Ronald! I just want to be sure of the wiring scheme between the Pixhawk and the ESCs.

            This is what i have understood, so far.

            1. The Power module will be connected to the Lipo and provide 2 outputs. The (i). six wire output cable will be connected to the POWER port of the Pixhawk. (ii) the XT-60 output will go to the PDB(Power Distribution Board).
            2. Connect the each of the ESCs' power cables(the thick red and black wires) to the PDB. The 3-cable(White-Signal, Red-BEC output, Black-GND) connector from each ESC will go to the servo rail of the Pixhawk. If the ESC has a BEC, it will also have a Red wire(BEC output) in the middle port of the 3-cable connector. I should not connect the Red wire to the Pixhawk(because we don't need to power the servo rail), only the Signal(White) and GND(Black) wires.

            Is that correct?

            What if i want to connect an RC receiver(FS-X6B), will i need to power the servo rail then? I think, the FS-X6B will have to be somehow connected to the PPM encoder and then the PPM encoder will be connected to the Servo rail pins designated 'RC'.

            Thanks a lot, for taking the time to help me out.

            • Hi Ashish,

              I looks like you have a good wiring scheme.

              If your power module did not come with your flight controller, check the pin order on the six pint connector as these are not always "standard." The existence of a red wire on an ESC does not indicate presence of a BEC. Power the ESC and check voltage between middle (red) wire and ground (black wire) to verify if a BEC exists and determine BEC voltage.

              If you purchased ESCs intended for multicopters, most likely there is no BEC, so you will need to purchase a separate BEC to power the FS-X6B receiver. This is good BEC:

              Your FS-X6B has a PPM output so do not use an additional PPM encoder.

              CTO, Kashmir Robotics
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              • And thanks for the UBEC suggestion.
              • Thanks a lot for taking the time to help me out, Ronald. I really appreciate it.

                1. to reiterate,
                (i) the above scheme for wiring ESCs is correct. This would also work with any EMAX ESC and i will be able to initialize and tune them etc.
                (ii) to power a receiver, it is necessary to get a BEC and power the Pixhawk's servo rail from it. The BEC will receive it's power from the PDB.

                2. Questions:

                (i) Is it a good idea to get ESCs with BECs in them and connect the output(Red) from one of them into the servo rail instead of buying a separate BEC?
                (ii) If there is no BEC, what purpose would the Red wire serve, if present?
                (iii) How do i connect the FS-X6B to the Pixhawk?

                • Hi Ashish,

                  If you have Simon-K ESCs you will only be able to calibrate throttle. If you have BLHeli ESCs you will be able to change many parameters. For your application both options are fine.

                  For multicopters it is better to use ESCs that do not have BECs. A single separate BEC is a better option. The one I recommended is an efficient BEC. Most integral BECs are not as efficient. Fixed wing planes often have just one ESC, and the integral BEC saves space and adds convenience.

                  A Pixhawk has one pin reserved for PPM input. Using a 3 wire cable (often referred to as a servo cable) connect the PPM output of your receiver to the PPM input of your Pixhawk. It might be labeled "SB"


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