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Quad not delivering power + worrying disarmed behavior
#1
My new build is exhibiting two behaviors that I can't understand yet. Thanks for taking the time to plough through this lengthy post!

1) [FIXED] When disarmed one of the motors is non-regularly receiving very short pulses making the prop move a tiny bit. 
    Min_command was too close to the calibrated low point of the ESC. Lowered min_command to 960 and haven't seen the twitch since.
2) When armed and in the air I can't achieve full thrust (and the quad yaws to the right about 25 degrees). 

I'm not sure which hardware/software component(s) are involved in these issues. 

First: the partlist
  • FC (new) - SP Racing Evo F3 (from cleanflight 1.13.0 to Betaflight 2.9.1). Default PIDs. Gyro @ 2khz, pid @ 1khz. Using Oneshot125.
  • PDB (used without issues on a previous build) - Matek PDB (link). With 1000uF low-esr capacitor added to the main power to tame motor noise.
  • ESC (used without issues on a previous build) - LittleBee 30A, BlHeli 14.6, Active Damping, demag low, motor timing med-high
  • motors (new) - Racerstar BR2205 2300KV
  • RX  (new)- Flysky FS-IA6
  • vCam (used without issues on a previous build) - Runcam Magnesium (PZ0420M)
  • vTX (new) - Eachine ET200R
  • Lipo - Turnigy Graphene 4s (1000mah and 1300mah) 

2) throttle / power issue
The quad takes off fine (given low throttle). I always take off in angle mode and then switch to acro (and enable airmode while doing so). Both these modes are functioning. My throttle issue occurs in both modes. I can take off and hover just fine, the throttle stick being at roughly 35%. Where it gets odd is when I increase throttle to about 50%. There's no changes in stability such as oscillations or shaking.. there's just no power. I've seen these motors on another build and they can give a hell of a punch. The other components should also be able to make this quad punch a hole in the sky but instead it rises very slowly. Notably, the yaw dips to the right about 25 degrees when increasing the throttle and will come back to its original heading when I decrease throttle again. It just seems like beyond a certain throttle point there's something holding the quad back, can't put it any differently. 
After a minute in the air the motors are slightly warm, nothing to be worried about. ESCs aren't warm at all, neither is the battery. The motors don't appear to get anywhere near their max rpm. In Betaflight in the motors tab (and props removed) the motors can spin up to max rpm no problem. 

I flashed Betaflight 2.9.1 to the FC, which it should support. On the first time flashing the process reported successful however the FC could only initialise one ESC (on motor 3). I couldn't get the other motors to turn in the motors tab. On the second flash all ESCs initialised and I could address all motors through the motors tab. I'm finding it a bit odd that my ESCs are giving the initialisation beeps out of sync of each other, but maybe that isn't too odd as long as all is well. But since all is not well I'm mentioning this just in case it's relevant.

This is the first SPI-based FC I have so I *could* go to 8khz/8khz but if I'm not mistaken I'd have to go to multishot so the ESC's can keep up with the short looptime. For my maiden I didn't find it necessary to flash the ESC's so I'm still running Oneshot125 with them and keeping my looptimes in Betaflight at 2khz gyro and 1khz pids.

I direct-soldered the ESC leads to the FC. Connections appear quite solid. I mounted the FC upside-down so I can have easy access to the SD card for Blackbox logs. 

update: I flashed Cleanflight 1.13.0 back to the FC and tried with that. No difference.

Some images of the build
[Image: L5voXju.jpg]
[Image: 3QVycDw.jpg]

Here's a video to show the issue. Hopefully it demonstrates the 'meh' throttle punch outs:
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#2
Could it be your motor timing? If I remember correctly, I run those motors on medium timing. Im not sure if it will fix it, but I would give it a try
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#3
Thanks for the input. I actually changed the motor timing to medium as well. No noticeable change at all. What's your demag compensation setting?
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#4
this is my BLheli settings (default BLheliS settings by the way). I'm using blheliS ESCs, but it should be about the same:

[Image: j2T9szH.jpg]


Can you do a blackbox log? it would be interesting to see the motor outputs. it looks like one of the motors is too weak, and the FC is reducing the throttle to the rest of the motors as a result
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#5
do you normally fly with your FC mounted like that? maybe it's shifting around even though it's on those antivibration mounts. that might be what's causing it to yaw. have you tried putting some nuts on there?
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#6
@JimmyLe813: I do use these rubber mounts quite often and haven't had issues with them before. If anything, they've helped me remove tons of potential vibrations to the gyros.

@oyvinia: took me a while to get around to continue debugging this quad. I got a new set of motors and replaced them all. Exact same behavior! Strange huh? I figured it might be a weak motor as well. I'm going to check the solder job of the ESCs on the PDB next. Still want that blackbox log?
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#7
Do you have ground connected to FC too?

Other than that idk. Did you check escs, or swap them?
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