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Quad motors get hot

cranialrectosis

Faster than a speeding faceplant!
Mentor
#1
I am running an 840g Anycopter with 10" booms and a KK2 board (v1.6).

Motors 2 & 4 get hot. ESCs 2 & 4 get hot.

The copter seems to be able to spin faster CW than CCW and I do not believe in coincidence.

I have swapped out the motors and props and re-connected all the wires.

I cannot recreate this on the bench with the rotors off.

I am running suppo 2208 1450kv motors and Ipeaka 22A (SK) Escs with a Turnigy 2200mAh battery.


It feels to me like the copter is having to spin CCW all the time to maintain hover and that is causing two motors to have to push harder.

Could this be a CG thing?
 

kah00na

Senior Member
#2
Of course you did the throttle thing with your ESCs?

If you don't have too much time invested in your config, you could reset the KK2 board and start over. Maybe you changed something unknowingly that is causing this.
 

xuzme720

Dedicated foam bender
Mentor
#3
Probably not a CG thing, but a yaw problem. Are you absolutely certain all the props are matched in size and pitch? Seems like it's trying to yaw in one direction more than the other and one set of motors is being forced to compensate...
 

cranialrectosis

Faster than a speeding faceplant!
Mentor
#6
I have done some additional experimentation.

Kah00na, I have never successfully synched my ESCs with the remote. It has never worked.

At the point where I plug in ESC 1 to provide power to the KK2 with my fingers on buttons 1 & 4 with the remote on and at full throttle, the KK2 simply goes to safe mode as per usual and there are no special beeps from the ESCs.

All my motors seem to start at the same time and the copter has been flying for several months now.


Furthermore, I re-built the copter last weekend. I moved the ESCs from the booms to the center hub. This means that the CG is much tighter to the hub as I have less weight out on the booms and more in at the center. This seems to have made it so my receiver which is slightly forward and port on the craft is now able to shift the CG port and fore. A basic hover now requires a tad of trim to balance out the CG.

I also note that when I land the copter and reduce to 1/4 throttle, all motors but one continue spinning. Motor 3 stops and sometimes has trouble re-starting (going to re-check the connectors on this one today).

I believe my booms are now flat, and my rotors are now (for the most part) on a parallel plane.
 

kah00na

Senior Member
#11
In the KK2 board menus there is a receiver test part. Did you use the sub-trims to zero-out all the pieces (aileron, elevator, & rudder)?
 

kah00na

Senior Member
#13
When you swing the rudder (yaw) back and forth does the receiver test move the same distance (+ & -) in both directions?

Also, just making sure because this is a toughy, in the "show layout" part of the KK2 board, do have the right layout chosen? I can't imagine it is wrong because you've been flying it for a while.
 
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cranialrectosis

Faster than a speeding faceplant!
Mentor
#15
When I swing the rudder in receiver test, it goes right-103 and left 100. So there is a -3 difference.

Motor config is correct and I am spinning my props and motors correctly and I checked to be sure.

My motors 2 and 4 still get too hot to handle after 10 minutes of flight. Motors 1 and 3 may get warm but it has to be a hot day.
 

Tritium

Amateur Extra Class K5TWM
#17
OK, Hot motors are NOT caused by any settings. Motors get hot because they are overloaded.

If you are running the same ESC's, motors and props all around then there is a drag on 2 motors as evidenced by both hot motors and the corresponding ESC's .

Either the bearings are bad or there is a physical obstruction to the rotation of those motors.

How are the motors mounted? Many motors shaft protruded slightly from the mount at the rear of the motor and if the mounting surface is not indented for the shaft then drag and overload will occur.

I have also seen dragging magnets and "trash" in the motor from manufacturing as well as from rough landings or crashes.

Thurmond
 

xuzme720

Dedicated foam bender
Mentor
#18
I would next try swapping one or both of the even motors to an odd position to see if the heat problem is following the motor or the ESC. Right now it's matching so if you move the motors and then the 1 and 3 motors/ESC's get hot then it's the motors...if not it's the ESC's.
 

cranialrectosis

Faster than a speeding faceplant!
Mentor
#19
The problem does not care which motor, prop, collette or esc is where. The current motor in 4 is new and has never been in any other location. The motors in locations 1 and 3 both got hot when they were in locations 2 and 4 and the motors currently in location 2 did not get hot when it was in locations 3. I did this all last weekend before I decided to ask for help. :)

The motors are mounted using M3 screws through an FT Anycopter G10 mount. The motor shafts are centered in the hole for the mount. I use all 4 screws. They are tight.

When the battery is disconnected and I spin motors with my hand I do not feel or hear any obstructions. I have learned to clean mud and grit out of my motors after crashes and am comfortable taking motors apart.

I know I am off a touch on my CG. The weight of my receiver pulls the copter a bit forward and left. CG is still under the KK2, however.


The symptoms make me think frame. I think I have something bent or twisted.

Is there a method to level your rotors? I am wondering if I have a mount that is somehow tilted or twisted.
 

cranialrectosis

Faster than a speeding faceplant!
Mentor
#20
One more thing I am considering. I use a quad copter power distro board. I am wondering if somehow I am over powering it (1450 kv motors and 8" props on a 3S) so I am considering building my own and seeing if that will fix the issue.