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Restricted motor amperage

#1
New to the hobby and having trouble setting up my first power system. Doing some bench test with a wattmeter to verify its operation before installing on the plane. I am only getting 10 A from a motor that is capable of handling 40. I have gone through all of the ESC programming options and tried each one. This is also a brand-new transmitter although after reading the manual I believe I have correctly calibrated all channels and assigned each one correctly. Basically, after about 60% throttle travel the amperage delivered by the battery remains constant throughout the remainder of the throttle travel to 100%. Could it be a bad soldiering job? Although I believe if this was the case I would not be getting electricity flow at all. Could a bed soldiering job result in reduced current? It just seems as if one of these components is restricting the amperage to 10. However, I am not sure which one. Could it be the receiver? I am using the three axis orange stabilizer version three from Hobby King, 2.4.

Motor is a Turnigy G10 810 KV
ESC is a 70 amp birdie
Battery is a 3S 5000 30C
Transmitter is a Turnigy 9XR (stock firmware)
 

Tritium

Amateur Extra Class K5TWM
#4
If only getting 10A for sure with a 12" prop then go to a 14X7" prop and see what happens.

Your 12" prop might do better with a 4S battery.

NEVER use Hobby King data except as a starting point as their data is not necessarily true.

Thurmond
 
#5
If only getting 10A for sure with a 12" prop then go to a 14X7" prop and see what happens.

Your 12" prop might do better with a 4S battery.

NEVER use Hobby King data except as a starting point as their data is not necessarily true.

Thurmond
Are you saying that the motor is reaching its KV rating at only 10 A? I guess that would mean that the propeller is not producing enough of a load to extract the power. Sort of like running the motor with no prop and drawing minimum amp?
 

Foam Addict

Squirrel member
#6
Have you calibrated your ESC yet? Ecalc said that You should be seeing a 31 amp load with that prop and battery.
Disregard all below til you recalibrate your ESC: Turn on your Transmitter, then set the throttle on your Transmitter to max, plug in the plane, wait for a "beep" or "Beep beep" from the ESC, then quickly move the stick to Minimum. You should now have better results.


I think that you need something more like that 12x6 prop on 4 cells to get anything near your 40 amp limit.
Look at Ecalc to give you a reasonable idea of amp draw and useful props. also use their Default P const. of 1.3, or else you will have wildly optimistic readings.
http://www.ecalc.ch/motorcalc.htm?ecalc&lang=en
 
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#7
Have you calibrated your ESC yet? Ecalc said that You should be seeing a 31 amp load with that prop and battery.
Disregard all below til you recalibrate your ESC: Turn on your Transmitter, then set the throttle on your Transmitter to max, plug in the plane, wait for a "beep" or "Beep beep" from the ESC, then quickly move the stick to Minimum. You should now have better results.


I think that you need something more like that 12x6 prop on 4 cells to get anything near your 40 amp limit.
Look at Ecalc to give you a reasonable idea of amp draw and useful props. also use their Default P const. of 1.3, or else you will have wildly optimistic readings.
http://www.ecalc.ch/motorcalc.htm?ecalc&lang=en

I am unsure what you mean by calibrate. According to the instruction programming manual for the ESC the procedure you described enters the setup phase for which there are many options to select. I have gone through all of these options. Examples are cell count throttle setting and brake. I agree that this propeller should be producing enough of a load to exceed 10 A.
 

Foam Addict

Squirrel member
#8
It should not enter program mode if you Immediately move the throttle down. This should be your best shot. Try that one more time, but as soon as you hear the Start up tone finish, drop your throttle down to minimum, if you hold it at max you will stay in program mode.
I hope this helps, and keep asking if you still need help!:D
 
#9
Nope. Still having the same symptoms. As a side note, I also tried and 11 X5 prop and am having the same exact issue. I'm beginning to think that the issue is with my transmitter. This is my first experience with a computerized transmitter and I find the set up and modification menus to be quite complicated. Turnigy 9XR. I feel stupid that the problem is probably obvious and I just don't see it or don't know to ask the right questions.
 

Foam Addict

Squirrel member
#10
No, it isn't obvious. And a motto of mine, is no honest question is stupid. Try this: go into your servo menu, and increase the throttle "servo" travel to maximum (150-200%). Do not recalibrate the ESC. Then try again.
Another possibility is that your ESC is bad. I have zero experience with birdies though.
 
#11
This really sounds like a trim issue. I am not familiar with Turnigy transmitters but I would be willing to bet there is a page that shows where all your trim points are set.
If the trim point is set to 25% then that is all you will get from the ESC no matter what prop you are running. See if you can find that page and adjust the trim to 100% and see if that makes a difference. WJ.