After taking apart my small BeeRotor Ultra 130 Carbon Fiber Mini FPV Racing Build (see here) to exchange the KISS 24A Race Edition ESC’s with the much smaller and lighter BeeRotor 20A ESC’s (Electronic Speed Controller), it’s time to rebuild the multi copter.
What happened so far?
We start right after the installation of the BeeRotor 20A ESC’s and the PDB, so we are just ready to prepare the wires for the power supply and the sensing of the (if you request I can show in detail how to crimp molex connectors)
flight controller (2x VCC (for Voltage and Current meter), 5V (to Power Supply of the BRF3), 2 x Gound(GND)),
the Video Transmitter VTX (12V, GND),
voltage sensing for the Spektrum Quad Race Serial Receiver w/telemetry SPM4649T (VCC, GND).
Powering the flight controller and soldering the ESC’s signal and ground wires
Next I am going to solder the 5V + GND for the FC and then the signal and ground wires of the ESC’s to the BeeRotor flight controller.
Connecting the flight controller (FC)
Now we connect the flight controller via USB to the computer and open Betaflight to have a look at the motor layout in the motors tab.
Soldering the signal wires
It turns out that motor 1 is on the back right, motor 2 on the front right, motor 3 bottom left and motor 4 on the front left position. So we are going to wire the signal and ground wires of the ESC’s in the same order to the flight controller. I’m sorry I’ve soldered them from the bottom, but I am sure you can imagine the process; if not please leave a commend and I will give you a more detailed description.
Testing the ESC’s and the motor direction – 1st magic smoke test
Now it’s time to test the ESC’s. For this we need some power, so I will solder the XT60 battery connector to the PDB on the bottom. I have used a used XT60 connector because it’s a rebuild.
When plugging in the flight battery it’s turns out there is no magic smoke and everything(ESC’s and flight controller) boots up correctly. Now it’s time to check if I have soldered the ESC’s in the right sequence and if the motor directions are right. To do so I plug in the flight battery and the USB cable to the Quad and start Betaflight. Then I go into the motor tab and try to manually spin up the motors. First I spin up all motors at once to see if they are all wired correctly. Then I check the correct positions by spinning up every motor in sequence, and then I check the direction of the motor.
Correcting the motor direction by using the BL Heli firmware
All motors check went fine. In the single motor check an anomaly appeared. Motor 1 has right position but wrong direction, motor 2 has right position but wrong direction, motor 3 has right position but wrong direction and motor 4 has right position but wrong direction. So, ok, I twisted the phases of the motors in the wrong manner when I soldered them to the ESC’s. This is not a big problem as the motor direction can easily be changed in the ESC firmware (BL_Heli). To do so I keep the flight battery and the USB connector connected to the quad and disconnect the Betaflight software by clicking on Disconnect. Now I start BLHeliSuite.exe and select under Select ATMEL / SILABS Interface the option SILABS BLHeli Bootloader (Cleanflight). If BLHeliSuite does not connect, try to cut every power supply to the quad, reconnect the flight battery and USB and try again. Now it should work out fine.
Connecting to the ESC’s with the flight controller
Next I click on Connect and then Check and after pressing Ok on the following dialog I gained access to the four ESC’s.
I didn’t describe every step for every ESC as they are all the same
Now I change the Motor Direction property on every ESC(right click on the Number under Multiple ESC / Master#1) to reversed, and the Motor Timing to MediumHigh, because the ZOE FPV 4100KV Motors I use in this build are medium to rather fast(I’am sorry but I don’t know a brushless build needing the fast option of the firmware, must be some secret super high KV motor setup) just click on Write Setup.
Recheck the motor direction in Betaflight
Now it’s time to disconnect BLHeliSuite and check the motor directions in the motor tab in Betaflight again.
Calibrating ESC’s in Betaflight
As you might have seen in the BLHelli screenshots there was very low value for PPM Max Throttle set(should be around 1997), so we have to do a ESC calibration in Betaflight. We don’t really have to, because we are willing to use DSHOT 600 as protocol which needs no calibration, but if there is a problem with DSHOT like a DMA conflict on one or more of the motor connectors on the flight controller we are going to use the multishot protocol which needs calibration. To perform a calibration we disconnect the flight battery and go into the motor tab in Betaflight. There we enable Motor Test Mode and pull the master slider all the way up.
Plugin in the flight battery to complete ESC calibration.
Now we plug in the flight battery. The ESC’s will indicate the calibration process. Now we pull the master slider all the way down to zero. The ESC’s will indicate the completion of the calibration process.
Testing the motor direction and enabling DSHOT 600 in Betaflight
We can slowly pull up the master slider again to check the motor directions. Everything is fine now. The next step is to check if it’s possible to enable DSHOT 600 in the configuration tab in Betaflight.
After activating DSHOT 600 click: Save and Reboot to continue. After the reboot we go again into the motor tab to spin up all motors to see if the DSHOT 600 protocol is working properly. Everything works perfect, nearly out of the box…nearly.
Mounting the ESC’s
Now I disconnect any external connection to the quad to continue the assembling. Next I will position the ESC’s, shrink the shrink tubes with a heat gun(or maybe with a lighter, soldering iron; but the hot air re-flow station gave the best results so far) and after that I fix the ESC’s with insulation tape onto the frame.
Finishing the rebuild of the BeeRotor 130 trainer
With some caution the heatgun worked well for the shrinking of the tubes, next I am going to mount back the flight camera, the top plate with the VTX and the Spektrum receiver. Before mounting the camera I put some insulation tape on the front of the copter right underneath the place where the camera will be placed, as the carbon frame is conductive and the camera could get damaged when shorted with the carbon.
Somehow I damaged a female molex connector when I removed the hot glue, but it seems I don’t need it anyway, as my custom crimped molex connector is 5pin and there is an other free 5pin female connector on the board where it is supposed to fit in(spoiler warning).
For god sake, I put some M3 nuts above and under the spacers to increase the space between the camera and the conductive carbon frame to prevent electric shorts.
2nd magic smoke test
Now it’s time to plug in the flight battery for another magic smoke test, it is supposed to check out if the FPV-System is working correctly aswell if the Spektrum receiver and the telemetry are working correctly.
The magic smoke test was successful, there was magic smoke. Now it’s time to take the multimeter and check where the short could be. You should really do that before plugging in the flight battery the first time.
Finding the short
After unplugging every part one by one and testing if the short still persists, it came out that the short ends if I unplug the connector on the FC where the sensor wires, for the voltage and current measurement, and the connector to the LED bar come in. So I will have a look at the BeeRotor flight controller manual to check if I eventually plugged the connector into the wrong place. I could also have had a look at the blog post where I disassembled the copter, but lets have a look into the manual just to get to know which part of the flight controller I might have roasted. It was the OSD, that’s not so bad as I don’t indent to use it anyways. Hopefully nothing else is damaged.
Finally finishing the rebuild
Now lets plug in the connector into the right place and lets repeat the magic smoke test, this time with a continuity measurement beforehand.
The second time the magic smoke test failed, which is a good thing, all systems are up and running, have a good flight.
The MTOW crime
We have a TOW of 270g where the legal MTOW is 249,9g, Fail; next time; maybe…
In my skill it flies like hell, very grippy, perfect for proximity!
KV suggestion because I have destroyed a ZOE FPV 4100KV motor
If you are trying to rebuild this build, you should take some lower KV motors then the 4100KV ZOE FPV motors I build in. With this props you won’t get all the power out of it. You would need some more torque or some lighter props. For the props I have taken you should maybe take some 3800KV to 3900KV motors, if you can find some. Hey, don’t care, at least for me the motors work incredible well. Sadly it took only 12 hours of flight time to destroy one of them by hitting a branch. It took me two and 1/2 weeks to get a replacement motor, it was delivered over Istanbul(not the best route for the EU).