Pixhawk and some ESCs with Low KV motors. Pixhawk is not the problem. Problem is related to ESCs, Firmware and fine tuning.

I Found a solution to the problem; I changed ESCs to Tiger Motor ESCs and changed the signal to 200hz.

More tunning on PID required, will try Autotune, however quad flies great on stabilized mode.

It is now clear that the problem is not related to PIXHAWK but to the ESCs and signal processing by the motors . As previously mentioned by experts in this Forum, the signal for Pixhawk is always the same and the controller is not the problem.

7/27/2015

Ok I accidentally sent a message to all the group, but I meant to make a clear declaration about PIxhawk.

For some reason, no one has ever found a resolution with the motor sync issue with some ESCs,( in my case with hobbywing 40a and 60a and the sudden loss of control of the Pixhawk due to signal malfunction with low RPM high pole count motors ( t motor 4008 380kv).

I believe it is important to mention, that after tunning, changing ESCs checking motors, and a few minutes of Stabilize and Loiter flight mode flight, switching to Pixhawk has been truly disappointing, and everyone should no that it will take some time to reach the " industrial" reliability and end user friendliness of the DJI Wookong M in the Pixhawk.

I believe it will be possible, but when there are potential to date unsolved issues, the community needs to be aware of them, in order to create proper expectations of Drone Builders and developers.

Pixhawk is completely incompatible with hobbywing Pentium 60 a and Hobbywing 40a ESCs. It Flips on necessary roll adjustments, and the motors are completely out of synchronization, even after adjusting RC signal parameters, PID adjustments, ensuring good connections, and checking motors and ESCs.

I truly hope the solution will be using DJI or T motor ESCs; however, there is a lot of people that are likely to try Hobbywing, or other brand high Amp ESCs with large motors, and my message is:

DON'T try it!!

You will spend more money, parts and time and brain power than simply using another controller.

Replies

- Henri > Rob_Lefebvre July 29, 2015 at 11:54am
  
  @Rob_Lefebre I like your secret. (Hobbywing)
  
  I like what I see about the "advertised performances" and I'm going to try them out.
  
  Thank you, Rob, for sharing your positive experience.
  
  This manufacturer mention on the HV80 Pro:
  
  -- Quote
  
  " The twisted-pair design of the throttle signal cable effectively reduces the crosstalk produced in signal transmission and makes flight more stable."
  
  Compatible with various flight-controllers and supports a signal frequency of up to 621Hz (Notes: all throttle signals over 500Hz are non-standard signals.).
  
  -- End of quote
  
  I'll try a number of different large pancake motors with it.
  
  (Currently using Turnigy dlux 80A opto)
  
  Again thanks Rob.
  
  Henri
- Muhammad Abdul Hadi July 28, 2015 at 9:17pm
  
  bro, I read elsewhere that one guy finally checked THR_MAX and found that somehow it was too low, try checking that too.....good luck
- Developer
  
  Craig Elder July 27, 2015 at 9:05am
  
  I would re-do the ESC calibration first. Some people forget / are not familiar with using the Safety button to calibrate the ESC. Look at the video on calibrating the Iris ESC on the 3DR you tube site. It will give you step by step instructions.
- rodger roth August 11, 2015 at 12:06am
  
  Hows it friend had the same problem beat me up also the solution were two fold i had a bad motor it still calibrated and telemetry was not giving me any help so like you i re did the whole cha cha the bad motor was messing with esc's (skywalker 25A 4in1 ) and one of my batteries did not survive a crash as well as ii thought and my flight times dropped from 17 min. to almost 4min, before battery FS landed it. physically check motor winding make sure none are lose. If you find any a performance check should be done. A fading motor will affect esc performance if you haven't done it yet check them u may have a damaged one also who u kidding u aint giving up on it shelving till more time maybe going till u fix it yeah
Paul Williamson July 27, 2015 at 7:21am

This thread has me a little concerned - I'm thinking the current combination for my next quad build:

- 700 size spider quad

- Multistar Elite 3508 274 kv motors (x4 obviously)

- 13x4 CF props

- TBS 30A OPTO ESCs running SimonK

- 3DR Pixhawk with power module

- 4S 5500MAH (thinking x2)

All of this talk has me questioning my component combination - the reason I went for the lower kv motors was to try and achieve better flight times on a high voltage system.

Does anyone have any suggestions - particularly around the FC/ESC/motor combination?

Regards,
- Paul Atherton > Paul Williamson July 27, 2015 at 1:43pm
  
  Paul, I think you need at least 6s power with those motors. You'll be lucky to get off the ground with 4s (unless you plan on connecting them in series perhaps?) You'll be looking at something around the 800kv mark on 4s with 1340 props to lift something around 2.5Kg safely. I would suggest trying eCalc for some basic specs - not always 100% accurate but a good starting point. Regards, Paul
- Paul Williamson > Paul Atherton July 29, 2015 at 12:24am
  
  Thanks Paul, yes series - I might shelve the 274kv's for another time.
- Cala > Paul Atherton July 27, 2015 at 2:15pm
  
  +1 and test sync problems running simonk and Low kv after fly
Muhammad Abdul Hadi July 25, 2015 at 1:44pm

@John & @Craig, thank you for clearing up the motor timing issue. My cuz had a similar problem once. The 600 would just power down on its own and come crashing down, twice, luckily on soft soil.
Developer

Craig Elder July 25, 2015 at 10:39am

@Pmarche, now that you have discovered the truth about Pixhawk and low KV motors and that the autopilot works fine with them and that you have discovered that the ESC firmware and configuration is the issue, I would like to request you revise your post with a supplemental paragraph about your new discovery so that other people can read the TL;DR version:
Pixhawk works great with low kV motors. Some ESC firmware and some ESC settings do not.

of 8

This reply was deleted.