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Author Topic: CC ESC at 4200 rpm  (Read 936 times)

Online Igor Burger

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CC ESC at 4200 rpm
« on: March 13, 2010, 01:38:18 PM »
Friend of mine sent me a question about CC ESC governor settings. He set 12pole motor at ~4200 rpm and got warning on picture. Is it true that CC cannot regulate so low RPM?
Or he missed some other settings? Or do you know any trick how to do it? As far as I know it is 10A ESC.

Online Dennis Adamisin

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Re: CC ESC at 4200 rpm
« Reply #1 on: March 13, 2010, 05:56:27 PM »
Hi Igor:
Castle Set Rpm mode prefers that you be somewhere between 70% & 85% of max RPM capability.  At kV=1360 with 7.4V the max is something like 10,064 RPM max, so it will give warnings below about 7000RPM and above about 8500 RPM give or take a little.

I have successfully flown at 52% throttle, your friend is going to be around 42%.  I'd say give it a go...

BTW if you want to see how it generates the "red warning, just enter diferent values for kv.  THe "Too slow" warning should disappear for approx kv=810  setting,  the "too fast" should appear at about kv= 665 (I think..!)
Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Offline Jim Moffatt

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Re: CC ESC at 4200 rpm
« Reply #2 on: March 14, 2010, 06:34:32 AM »
It is also possible that the warning comes from the fact that the rpm is below 50% of the Kv rpm. The plot below shows that increasing the throttle opening on a typical motor (over)loaded so as to be below 50% of the kv rpm will actually slow it down - not to mention possibly burn it up! If the motor is not overloaded operating with partial throttle in this range will work fine.

Online Igor Burger

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Re: CC ESC at 4200 rpm
« Reply #3 on: March 15, 2010, 03:08:43 AM »
Castle Set Rpm mode prefers that you be somewhere between 70% & 85% of max RPM capability.  At kV=1360 with 7.4V the max is something like 10,064 RPM max, so it will give warnings below about 7000RPM and above about 8500 RPM give or take a little.

Thanks Dennis, throttle % was the reason, not too low uncontrollable rpm (that's what I affraided of). I told him him to set lover voltage and warning dispaeared. So he set it back and tested governing without prop (just braking by fingers), it worked well. So everything is OK.



BTW .. this guy on video started last year and he already did whole program ... looks like indoors are good way (read safe = cheap way) to learn all fugures  ;D

Online Igor Burger

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Re: CC ESC at 4200 rpm
« Reply #4 on: March 15, 2010, 03:16:11 AM »
The plot below shows that increasing the throttle opening on a typical motor (over)loaded so as to be below 50% of the kv rpm will actually slow it down

Hmmm ... nice picture, but I think I do not understand that "throttle %"
1/ I do not see throttle % on the graph
2/ increasing throttle can increase input power much more than output, it can lower efficiency lot, but how it can DECREASE output power? longer PWM impulse will push more amperes via winding and that will make higher moment and it will rotate the same prop stronger = higher output power ... does not matter what loses are

Offline Jim Moffatt

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Re: CC ESC at 4200 rpm
« Reply #5 on: March 15, 2010, 07:12:02 AM »
Igor

The pic below illustrates what I was trying to say. In the region to the left of the red line, increasing input power (top line or throttle) actually reduces prop power and slows the prop down. All of the throttle increase would go to heat (loss).  Although no one would ever operate with a motor in this region near full throttle, the CC esc probably does not know this. It is a somewhat ridiculous case. Unfortunately I have tried to operate motors at full throttle in this region with disastrous results.    HB~>

To explain this a little more the curves represent what happens at WOT ( wide open throttle ) under varying prop loads. The throttle and governor always reduce power from WOT. But if WOT is in the left portion of the curve the governor will not work. The green area in the graph shows the proper prop load to use with a given motor at WOT. When the motor is operated in this region the governor will work reguardless of motor speed. The only exception would be if the software is not designed to go below a certain speed.

I know this explanation leaves a lot to be desired. Its the best I can do for now.
« Last Edit: March 15, 2010, 05:39:19 PM by Jim Moffatt »

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