Any ideas?

[Dave1701]

My gb 130 has taken to dropping out the sky, I initially changed the receiver as I thought fail safe was kicking in, it does the same. I have since noticed motor 3 becomes intermittent after a short time and will not pick up enough speed to take off. On the bench tonight it pulsed but wouldn';t run consistently and was noticeably warmer than the other motors. The motor is an Emax rs1306 kv 4000, it is a cw motor which I have running ccw .... Is this an issue. ?
I also wondered whether it could be the esc (dys 10a blheli) that was failing.
Flight controller is spf3.
Has anyone got any ideas before I start ordering random parts and swapping them.[emoji52]

[Cheredanine]

If one mootor goes typically the quad will not just drop out the sky but spin towards the motor that has gone, very different from failsafe where all motors cut out. Can you describe what is happening a bit more?

[Dave1701]

I';ll try. The quad will fly well for 30 seconds or so then when changing inputs , either throttle up or quick turn etc it fails usually spin over a couple of times, it doesn';t just stop and drop. Tonight it did this twice, the 2nd time very soon after the 1st then failed to take off. Motor 3 was only turning intermittently the other motors didn';t seem to develop enough power to flip the quad over. Strange.


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[Cheredanine]

So my first gues would be desync due to failed crossing detection, it usually happens if min throttle is too low at the end of fast flips or rolls and results in one motor failing to provide power, once you have crashed and it isn';t providing power I am guessing crash caused physical damage, check the solder joints etc

[Dave1701]

Ok cheers. What confuses me is that this issue has been happening for a while. My guess is that it will fly ok tomorrow for a little while then fail again and the heat in the failing motor concerns me. I have already checked the solder joints briefly which seem ok . What would prevent the failed crossing you mentioned.


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[Cheredanine]

As the motor rotates he magnets move through the fields created by the coils, the crossings are when the magnets cross from one field to the next, the esc should detect this through back emf and change the current through the coils appropriately.  Particularly when a motor is not under load it is difficult to detect, different demag compensation and motor timing will be needed
So let me ask
1. What motors are you using (make, size and kv)
2. What props are you using
3. What escs are you using
4. What cell count are you using?
5. What protocol are you using (e.g. Oneshot125, multishot, dshot)
6. What min throttle / digital idle are you using?

[Dave1701]

Ok see my first post for motor and esc make etc. I use one shot 125. Min throttle may be an issue as I remember lowering it in clean flight due to motors rotating at idle when linked to computer. I';m using 3in triblades  for props.



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[Cheredanine]

Ok yeah so have you changed demag or motor timing in blheli? Stock settings are for bigger slower motors, I would expect demag high and motor timing high or medium high is needed (having these too low will produce desync, having too high will produce heat)

Min throttle should be 30 points higher than the point where motors spin up
What is your pid loop set to? (In He or kHz)

[Dave1701]

Will have to look into that tomorrow as quad is in shed asleep! I have not used blheli with these esc so they will be as they came to me but this info is useful as I am currently putting a 210 together from scratch and don';t want to make the same errors with that one. Will post tomorrow evening.


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[Dave1701]

Thanks btw


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[Cheredanine]

Ok mate, the reason I asked for loop time is with oneshot125 you can not run 4khz or faster, the signals at full throttle will bomb

[Dave1701]

Paid loop freq is set to 2.67 kHz .
More info .... When in blheli and testing the motors/ calibrating the esc motor 1 spins erratic and slow then stops and there is one beep from the esc, motor 3 spins fast at first then does the same.
I have changed the demag and motor timing in blheli.
Min command is set to 115, min throttle to 1087 ( motors spin up at around 1057)








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[ched]

Coming at this from a different angle. It could be esc or motor. So swap 2 motors. If the fault is still on same arm then its esc if it moves to other arm its motor.

[Dave1701]

Yeah that was my first thought and I have ordered a motor and esc just in case however from today the same issue as developed in motor one whilst on the bench. I have flashed them in blheli and as I say it seems to behave slightly different in betaflight when testing the motors . Confused


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[Dave1701]

Just tested again in betaflight. both motors rotate 4 times in slow pulses and then the esc beeps once. the esc will beep again when I throttle down. When armed and using the radio to throttle the motors motor 1 will behave the same but will respond to me moving the quad , motor 3 doesn';t respond after initial throttle up. Motor 1 has become really warm .

[Cheredanine]

1. Motors should not spin during calibration, typically this will happen if "program by tx" has been disabled. Re enable
2. Min command should be 1000

Try demag low, timing medium high, may even be necessary to turn demag off

[Dave1701]

ok done that. motor 3 spins upfor a while then pulses 4 times and esc beeps as it stops. motor 1 just pulses 4 times then stops.

[Cheredanine]

Ok mate so recalibrate from the motor tab and describe what happens when you recal
(Don';t test afterwards, just do the recal, let';s take this a step at a time)

[Dave1701]

sorry to be dense but are you talking in betaflight or blheli

[Cheredanine]

Always cal in bf/cf

When you cal you are basically telling the esc what minimum and maximum throttle looks like, if you do it directly it is reasonably accurate but if you do via bf or cf you allow for any idiosyncrasies of the fc, the wires and the soldering

For reference,(just in case)
Take the props off
Go to the motor tab in bf
Click the little check box at the bottom right,
Slide the motor master slider to top,
Plug the battery in
Wait until beeps finish
Slide the master slider to the bottom
Wait for the beeps to finish
Unplug the battery

[Dave1701]

done that and had the normal tune from the esc';s, have not tested.

[Cheredanine]

Ok mat e so now, without putting props on
De power the quad.
Reconnect to bf and go to the motor tab
Plug the lipo in
Click the check box and one motor at a time gently spool it up to about 1150
Then spool it back down and move to the next motor

This is checking basic functionalit

[Dave1701]

ok. motors 2 and 4 fine. motor 1 4 turns intermittent then stop esc 1 beep. motor 3 ran fine for 20 secs then 4 intermittent turns then stop.

[Cheredanine]

Ok so clearly those two motors have a problem
It may be at the flight controller end, on the wires, the esc or he motor, check all solder joints, make sure ere are no thin wires shorting, the as others have said, time to start moving components and see if the problem moves

[Dave1701]

cheers. will have a look tomorrow and report back.

[Cheredanine]

You might check the mounting screws on motor 3, particularly if it is getting hot.

[orfordness]

Did you say you';d pranged it in? are you using a PDU or the base board of the quad to distribute power?
Any chance it occurs when there';s flexing in the plates? May be an internal fracture?

Steve

[Dave1701]

Today I have swapped two of the motors and still motors one and three were failing. I then swapped two of the escs and the problem followed the esc !!! Any idea why two escs fail with very little use and no major crashes? At 10 A are they likely to be ill equipped to deal with those motors (rs 1306 4000kv)


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[Cheredanine]

Not an expert on the micro class it would in any case depend on the cell count and props used

[xxpitt]

i';ve not read through all the answers, but i had a similar thing happen to my quad, when i looked at hd footage and slowed it down i seen front left arm was dropping first. i inspected that esc and found a small resistor/capacitor or something was missing, quad flew fine intil a hard input then it would roll out the sky. try seeing if you can see what arm is dropping first and switch out that esc, if you dont have a spare you could just swap the esc around and see if the arm you move it to starts dropping 1st. if so you know its the esc. if its still the same arm dropping the next guess would be that motor