Hi Guys  ,

I am facing a strange issue with my brushless motor!!!!! 
Whenever I start increasing  the throttle, at around 70% prop RPM reaches max and after that there is no increase in RPM till 100% throttle. I tried different props and of course without prop, but same thing happens. I actually didn't measure RPM using any meter, but I observed the sound of the motor and I  have concluded that it's not increasing (May be I am wrong judging motor RPM this way) but I also noticed there is no increase in power while holding in hand and while flying!!!! I do have some Turnigy motors but I am not facing this issue with those!!!!!!

The motors I am talking about are:
1.   FC 28-05 Brushless Outrunner 2840Kv: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=5353 with TURNIGY Plush 25amp Speed Controller on 3S lipo
2.   EMAX CF 2822: http://www.rcdhamaka.com/index.php?main_page=product_info&cPath=58_59_93&products_id=391 with TURNIGY Plush 25amp Speed Controller on 3S lipo
3.   C20 brushless Outrunner 2050kv: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=6634 with TURNIGY Plush 18amp Speed Controller on 2s Lipo

I am using same ESC for both option 1& 2 swapping at field whenever needed. I do have some Turnigy motors as well with HXT ESC but I am not facing this issue with those motors. I also had combination of above Turnigy 25A ESC and hexTronik 24gram Brushless Outrunner 3000kv, it also worked just fine, without any issue!!!

I am not sure why I am facing this issue but seems like motors are not able to deliver full power because of this. That is why I am posting this issue so that if anyone can address this!!!

I started to doubt that if  ESC timing got to do something with this? And how ESC timing which is generally low, mid and high affects motor, how to decide what is correct timing for motor? I do have programming card for these ESC. I never tried changing timings, but if anyone could tell me understanding how it affects motor then I think I will give it a thought!!!!

Just in case, my TX is JR 7202 & DX7, RX  Corona 72 Mhz synthesized and spectrum AR6110.

Plssssss help!!!

The range over which power is delivered is set by letting the ESC learn the max throttle position (usually done by powering up the ESC/motor with the throttle set to highest on the stick, then reducing it to lowest).

I am a bit confused by your long description above, on what combinations are working and what are not, so the above point may be irrelevant.

Quote from: anwar on July 02, 2010, 01:58:21 PM
The range over which power is delivered is set by letting the ESC learn the max throttle position (usually done by powering up the ESC/motor with the throttle set to highest on the stick, then reducing it to lowest).

i never tired this, i usually start with throttle at min, so i will give it a try!!

Quote
I am a bit confused by your long description above, on what combinations are working and what are not, so the above point may be irrelevant.

hmmm.... yes its little long......
the combination mentioned with points (1,2&3) is not working, rest others are examples in which i am facing no issues!!!

Please do keep away from the prop and secure the model the first time you try this, in case the ESC does not recognize the max throttle as an attempt to teach it and decides to take-off instead !

Quote from: anwar on July 02, 2010, 03:04:52 PM
Please do keep away from the prop and secure the model the first time you try this, in case the ESC does not recognize the max throttle as an attempt to teach it and decides to take-off instead !

yes of course!!!! but i think most of the ESC hav safety feature, and doesnt arm unless throttle is set to min and most of my ESC have this feature!!! if it si not set to min after powering up then it keeps on beeping!!!!

one more thing any idea about ESC timings!!!!

Dont increase the ESC timings for these motors, it may even burn them, Increasing the timing increases the frequency of the pulses sent to the motor. This is great for big motors which required lots of power and more poles are present, though not recommended for small ones.

Just do a throttle range setup w/o the prop on the motor as anwar suggested.

Was this resolved? What was the problrm?

Hi Ash,

I am facing the same problem. I have also tried to change the prop, esc timing etc. nothing is working.

After increasing the throttle above 70% the motor makes a weird noise and it stops.

Although, I changed the EPA setting to 60% and then the motor works but becomes very hot.

Try changing your EPA settings..

If above 70-80% motor is stopping then its probably that your ESC is not big enough as the motor is demanding. I had the same problem with HK 18-25 ESC which give burst mode for 5 seconds and after running super fast for just 4-5 seconds the motor will stop and keep beeping. I put a 25-30ESC and it is working fine now.

Another thing you might want to check is if your RX is digitally trimmed to keep the motor running on low speed and limited to just 70% or similar. Dx6i has this feature so you might want to check that as well.

Quote from: atul_pg on December 04, 2010, 12:27:03 PM
I am facing the same problem. I have also tried to change the prop, esc timing etc. nothing is working.
...
Try changing your EPA settings..

What motor are you using? What is the Prop? What is the ESC you are using? What is the battery? What are your Tx EPA settings on Throttle? Are you in Heli setup (if so, then what is your throttle curve setup?)

All this i required to make an accurate analysis.

@Saurabh... you sound like a perfect fit for tech. support. If you are not already into it (no offense hehe)

Thanks Vikas

I know ... just common sense and logical approach. trying to help friends... 

I had exactly the same problem but with a brushed motor but fixed it up by tightining the can of the motor.

I guess it was due to the loose can that caused imbalnce in the mag. flux.

I also had the same problem once with 2204 motor. but that time i was new to brushless motor. i also have 2212/13 motor which works perfect on same ESC. From someone or somewhere i came to know about min and max throttle setup in ESC. I set those settings which took 30-40 sec, and all set.
Process of setting min and max throttle : Push throttle lever to max position and switch on the ESC. after beeps pull back throttle lever to min and switch off the ESC. Switch off the TX.

Sandeep

I believe it was mentioned that you are not sure whether the speed was actually increasing or not. There is a simple crude way to check this:

Use a cheap Chinese digital clamp- on multimeter with the clamp-on arms put around any one of the brushless motor wires going from the esc to the motor and the meter set in AC current mode. The reading will show some value. An increase in value exactly tells you whether the rpm is increasing. Actually it tells you whether the current thru the wire (read  that phase of the motor ) is increasing or not. The values if co-related (calibrated) to actual current thru the motor, can give a fair idea of how the current is changing. This method can also help you understand whether each of the phases are balanced... if not balanced, it could also mean that there is a loose contact.

My experience tells me that the topping off could be a contact resistance problem (connectors between the ESC and the motor). This could especially be true if the male part of the connector has its spring  contact plate rotating on its stalk.


Saju

most of such issues are because of wrong calibration of the throttle. Ensure you read the manual of your ESC to calibrate the throttle and check again. The next thing is the timing. most of HK SS series ESC do not support timing above 2000 kv. rest are loose connections and incorrect combination of motor/ESC/Prop.