Front motors are getting hot.

[jevermeister]

Hi,

I just noticed, that my front motors are getting hotter than the rear motors (I noticed it with front mounted empfty GoPro casing) so the center of gravity is slightly moved forward.


I use eMax CF2822 cheopo motors on a 1 kg Quad with 10" props and 12A Turnigy Plush set to HIGH Timing
Props are balanced (not perfect but good enough all axes are corrected so the rotor/stator is not sitting to tight.
I never checked the temp before so:

How hot is normal after 3 min of flight?

My motors are getting noticeable hot after just 3 min. A little hotter and you cannot touch them without pain. :-/


Is the high timing a problem? Or are the motors broken?


Nils

[Katch]

Too hot to touch is too hot. My motors/escs run very cool and are just warm after 15 mins of fast forward flight.

[jevermeister]

So what is wrong with my copter, I have some bad vibration after some crashes and are about to review the copter and fix the problems - can vibrations cause this?

Nils

[refractions]

Have you tried running your motors without props installed? 10" props sounds a bit large for that motor.

Try this link and see what it says:

http://www.ecalc.ch/xcoptercalc_e.htm?ecalc


Iain

[Katch]

Have you tried running your motors without props installed? 10" props sounds a bit large for that motor.

Try this link and see what it says:

http://www.ecalc.ch/xcoptercalc_e.htm?ecalc


Iain

Yup sounds like you are swing too props that are too large.

Other possibility is if your bearing have worn out or a crash has bent the shaft slightly leading to increased friction and work for the motor causing the heat.

I'd guess the first is most likely the case in this instance.

[jevermeister]

Hi,

I switched to 8" props but the result is the same - the motors are getting really hot. I also noticed, that the ESC (Turnigy Plush 12A) are getting hot too. The voltage supplay remains cool though .
Battery is slightly warm but alle the contacts on the power distribution are cool.
Is it possible, that the high timing rate of the ESC are causing them to heat up?

I will now change axes and bearings on the front motors. I do not think the props are the problem - the rear motors are spinning the same props and are not getting very hot.

Thank you for your help.

Nils

[chris ables]

Are you running motor connectors? And if so you need to hardwire them!! Bad connectors can cause heat.

[jevermeister]

Are you running motor connectors? And if so you need to hardwire them!! Bad connectors can cause heat.

nope, everything is soldered directly - no connectors between lipo ESC and motor.
only PWM wires are connected via connector.

I just found a stone stucking beneath the motorbase FR i fixed it and will try again this evening and will repoert back if this fixies the problem -

no opinion about esc timing?

Nils

[Pyrofer]

You must have SOMETHING between lipo esc and motor, or you wouldn't be able to charge or unplug the battery.

[jevermeister]

you are right... a lipo plug... d'oh

[chris ables]

you can change front motors to back and if same motors get hot that will tell you if it's the motors are the problem! Might be the bearings !!

[tovrin]

http://www.ecalc.ch/xcoptercalc_e.htm?ecalc

if you plug your copter info into this calculator, does it show that your nearing the heat range of your motor on the graph at the bottom of the page?
if so, your addition of the camera might be adding a bit too much stress to the front motors. try moving your battery to the back of your frame a little to adjust your CoG. see if that shifts the heat balance a little.

or simply remove the camera and see if the problem goes away. it may simply be the camera weight forcing your front motors to work much harder to maintain level flight. the gopro with mount weighs close to 200 grams, i believe, and that's a significant shift of weight on my smaller copter. on a much larger copter i would assume not as much but it is still going to register a difference in motor usage, which in turn will add heat.

[LenzGr]

So what is wrong with my copter, I have some bad vibration after some crashes and are about to review the copter and fix the problems - can vibrations cause this?

Vibrations and excessive heat are a common sign for worn out/damaged bearings, likely caused by a crash. Do the motors in question "feel" different when you spin them manually? Do they all spin up at a similar speed? This might also be a reason for motors stopping in mid-air, so it's definitely to investigate/fix.

[jevermeister]

1. replaced Props to 8" -> no improvements
2. replace bearings
3. replaced motor bell
4. replaced shaft
5. replaced prop adapter with prop saver: Motor is 51°C hot other motors are about 45°C
6. switched timing from high to middle.

I noticed that the motors are vibrating at higher rpm.

Is it possible that the vibrations drive the gyros nuts and that the FC tries to compensate the disturbances by shifting RPM and this is heating everything up pretty bad?
Now??

Nils

[Katch]

if they are vibrating they are unbalanced and therefore less efficient and therefore generating more heat.

[kos]

those motors are designed for 8 X 6 up to 9 X 3,8 .. and draw 18 A

the average middle range motor will spin 10 X 3,8 .. at 12 A

changes for more efficient motor or remove weight ?

[refractions]

Have you tried balancing your motors?

This link shows an easy way of doing it.

http://youtu.be/OgvayWfey78

You can also get a "seismograph" app for android and apple mobiles. Install and place your phone on the motor arm and watch the graph - works quite well.

http://youtu.be/_yLRGF5_4XU

[jevermeister]

I wish I tested the temps right after assembly so I would now if there is a systematic flaw or if something is broken now.

I will try the balancing tomorrow - what a bummer that my motor mount is build in a way that prevents me to attach stuff to the bell.

I will test the vibes via the gui with the motor testing version of multiwii.

Nils

[jevermeister]

I just measured the curren on the FL ESC with the hot ass motor: it is drowing max 10,45A and 9A mean current at full throttle.

That is sounding ok to me.

Nils