RC India

Well...... manage to get myself into trouble even before takeoff...

I had been testing the motor with different ESC timing. I ran on high timing at about 60% throttle for about 3 mins when the motor came to an abrupt halt. There was little bit of smoke and the ESC started making some wierd noise.

I quickly disconnected the battery and opened up the cowl to reveal the motor. At that point I observed the following.
  The bullet connectors (motor to esc) were hot.
  The motor was very hot.
  The ESC itself was barely warm
  The battery was in room temperature.
  Of the three motor wires (Red/Black/Yellow) the red one has become rigid.
  On the coils, there is some yello stuff - looks like varnish/resin that has melted and accumulated.

I let the motor cool for sometime, disconnected the prop and after about 15mins, tried to wire up the motor again. The ESC boots up fine - as per the sound. At first the motor started spinning, but halted after a few seconds. Subsequently the motor runs very slowly with a lot of vibration. Its shaking more than its turning.

So what could be the problem? I dismantled the case to see if anything is burnt or not, but all the magnets seem to be tightly glued and coil does not seem to be burnt.

Pankaj
 

It might be that one of the motor windings are shorted internally. The yellow gunk is a good indication of something cooked up there. I would suggest not to run the motor again else you risk your ESC or battery getting damaged. Note that unbalanced commutation will create huge pulsating current spikes which all batteries hate.

-Ismail

Try to smell the portion with the yellow substrate (burned varnish which insulates the copper wire). If you smell something different, probably you have fried the winding of the armature. This would have either short circuit the winding or opened the winding. Take a multi meter (preferably a Digital one) and  take the reading of resistance of the winding in good condition ( you might need to de-solder one end before measuring) and then measure that of the one with the fried one. Any difference may suggest the problem.

If you have patience of repairing the motor:

1. Get the resistance of the armature in good condition, if individual armature coils are soldered at both ends to some strip, leave this step otherwise.

2. Unwind the burnt armature completely and measure the length. Note the wind direction as it is crucial. If the coil ends are not soldered and same wire goes to other armature, you may need to cut the wire, leaving more on the good coil ends.
 
3. take the wire to local fan/cooler repair shop and show the wire to get new winding wire of same SWG (I can tell you to measure yourself). You can verify if the wire you bought is right. Wind 10 turns of the old wire on a pen and measure the winding length. Same number of turns of the new wire should measure the same length. Ask the repair guy to give you some varnish he uses to dip new wound armature.

4. Now cut length of the new wire as measured in (2) and wind the complete length on the unwound armature in the original direction.

5. The completed armature winding should have same resistance as measured in (1) - just as double check. Solder the wire.

6. Replace the Red phase wire with new one (if  you can't get silicone wire, 12SWG 'Felexible' wire sold at electronic store would do.

7. now pour some varnish drop by drop (very slowly) on the new wound armature, till the coil ceases soaking any more varnish. Avoid spilling the varnish to adjoining coils

If you are not in a mood to take the pain of repairing it, I am shameless to take it as 'donation'  (:|~    

Thanks Ujjwaana, but there is a problem, I do not see any soldering in armature, so I guess its one big coil

Not much use  now though but I prefer to keep it simple  and use factory default settings  to run my system  even now , don't complicate life  by  using programing on which I have no first hand experience .

From what I have read on your motor till now I guess there was some issue with the motor  to start with because from my experience with  electrics till date I have not had the problem of a new motor screeching or  behaving the way you have described it . I have never had to  change any factory settings on any of my systems till date  leave alone changing the timing nor change to soft or hard start .

I have found that they have always been plug an play for all my set ups from the smallest to the 60 size .



Sai

This motor that I used from HC, Turnigy Aerodrive, even in the site lot of reviews about the screeching noise and everyone reported that changing timing did the trick - however, noone reported a fried motor.

Anyways, more than the problem itself, I need to determine the cause so as not to repeat.

The ESC was cooled because it was outside. Possibly, with the cowl on, there was not enough wind flow to cool the motor and hence the coil fried. Could this be one of the issues?

Yes pankaj, I have seen the ends soldered only in the larger sized motor( and the much costly German ones). Unless you are not sure that the coil is burnt, don't cut and open the winding.

If you don't plan to maintain a motor/engine museum, you always have the option to donate to more adventurous ones  ;D

all the best for the maiden flight!

Three Questions....

1) How to determine if the ESC is damaged or not? Well, it is supplying current to the motor and the poweron self test is OK. Does it mean it is working correctly?

2) While doing static test on ground, is there a limit on how long the motor should be tried safely?

3) When starting up with the motor, is it advisable to try with a lower prop dia/pitch and then move up? Is so, then how small should one start with?

OK, the new motor arrived 2820 from Sai and I tested the setup. The ESC is OK, so I guess, its only the motor that got fried.

Which means that newbies should not test their motor on full throttle on ground for a long time....

Pankaj

Among all the IHS/LHS sites, I see one of the best value of larking on HC sites is the review of most of critical items like Outrunners/ESC/LiPo/Engines/ARF etc. The number of review/feedback on HC generally leaves any other big brother like Towers miles apart. I marvel the helpfulness of many hobbyist out there publishing break-in reports.

If you can find the motor/ESC/LiPo on HC, that you are buying from LHS, its best to spend some time reading the review by people. It gives a good first hand suggestion regarding performance numbers of prop, cell run time, condition after run (temperature/sound). The most handy information for me are the wattage obtained by different props on a motor.

Even if you cannot find the exact motor, finding a close match with Volt/Max Amp/Kv on a motor on HC would also help. There used to be a motor/prop calculator on www.slofly.com. Sadly the site is down for ever (as it seems from posting by the owners) May that wonderful site rest in peace. Any one made a local copy of the site ? In college days we didn't use to have Net access in hostel rooms, so I used to make complete mirroring of few useful sites ( few sections ) using HTTrack. Many people might find this laughable now, with brad band proliferation.

Try this http://web.archive.org/ or any of the other archive sites.

Iv had a similar problem -

FC 2822 motor. HK25-30A ESC. 3s lipo.

I tried the motor without prop and it worked fine - trial was for few seconds without full throttle.
Tried it with 10x6 prop at less than 1/4 throttle and realized the prop was spinning in the wrong direction. Swapped two of the 3 wires from motor to esc and tried again. At 1/4th throttle motor was spnning and not hot, ESC was warm and not even near hot. Between 1/4th and 1/2 throttle esc became very hot and motor started making noise and little smoke, so i stopped immediately. When i tried again motor would tremble but not spin.

The prop i used 10x6. On HK it says the motor draws 14.5A for 10x5.

heres a video:
http://www.youtube.com/watch?v=qRYBTURYh7I

Did i do something wrong??

What happened? By the way motor is turning looks like an internal short and your ESC might have fried. If there was smoke there are chances that the coating in the winding would have come out and if there is a short your ESC might have gone. Check your esc with your other motor.

The esc is fried. I removed the shrink wrap. Two FET's have a yellow colour to it. And it smells funny. I guess the HK reviews arnt to be trusted. I read in a review that 10x6 should not be used even though the sticker says 9-10". GRRRR...
One question:

Say i use anoter 25A esc and a burnt motor - will the burnt motor fry the esc?

Oh no..But y did it burn? My same motor took 10x6 the other day you saw?

Yeah it did. You ESC was also 25A right?

It worked fine at low throttle then started making "grrrk" "grrk" sound. I used a wire to extend the motor terminals to reach the esc. Can the wire have caused any problem? Definately no shorts as all me connections have been shring wrapped. Lipo is unharmed.

Yah its same ESC. Bring the dead motor and ESC sometime, we will do an autopsy of that  :).

Yeah sure i will :) Need to get new ESC and motor now :(

Can someone point out as to what went wrong?

Problem solved. This is how it went about:

Was preparing electrical setup for a model. I used HK18A esc, CF2812 motor and 2200mah lipo. But when powered up the motor kept vibrating exactly like my CF2822 motor even though all components are new ( refer aove video).
Read online that connectors could pose a problem , so i removed the bullect connectors between ESC and motor and soldered the wires directly. It worked like a charm.!
I have decent soldering skills and was surprised with the reason for failure!

 :giggle: :giggle: :giggle: :giggle:
I thought you would again stop building after frying another motor  :giggle:

I had been confronted by the same problem and the solution was the same.