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View Full Version : What is causing an esc to over heat my motors?


jaycook777
01-28-2010, 01:43 AM
I'm new to electric flight, but I've had 4 different electric craft now.

I just bought a Turnigy K-Force 40 amp esc and ran a motor I've had great success with. It was a Turnigy C3536-1100 and that motor fried in minutes. I thought it was the motor's fault. I just got a new Turnigy SK3530-1100 and it's getting over heated also in just a few minutes. Can someone explain this to me? ????

I have good airflow, and the first motor I had was in my Parkzone Corsair and was ran by an 80 amp K-Force esc for probably 50 flights. It was fine, I just got the smaller esc for a smaller plane.

The esc came programmed at 15 degrees, and I tried changing that to 11.5. And I tried the other two motor settings ie Normal, Special 1, Special 2. I have no idea what the other two setting are, but they made no difference either.

Thank you for your time,
Jay

cisc0box
01-28-2010, 01:45 AM
Interesting ... someone recently caught fire their Hawk Sky and was using a Turnigy ESC at the time it happened.

He stated that he used Turnigy's before without any problems but this makes me wonder. Maybe their speed controllers are having issues ...

jaycook777
01-28-2010, 01:55 AM
I never had motor power problems with the Turnigy K-Force 80 amp, but I did get a BEC voltage drop that made my Corsair crash. I know this because I had the Eagle Tree Data Logger onboard and could see the voltage drop after looking at the data.

cisc0box
01-28-2010, 01:59 AM
I know he was using the 30 amp when his plane caught on fire ...

ministeve2003
01-28-2010, 02:44 AM
I'm new to electric flight, but I've had 4 different electric craft now.

I just bought a Turnigy K-Force 40 amp esc and ran a motor I've had great success with. It was a Turnigy C3536-1100 and that motor fried in minutes. I thought it was the motor's fault. I just got a new Turnigy SK3530-1100 and it's getting over heated also in just a few minutes. Can someone explain this to me? ????

I have good airflow, and the first motor I had was in my Parkzone Corsair and was ran by an 80 amp K-Force esc for probably 50 flights. It was fine, I just got the smaller esc for a smaller plane.

The esc came programmed at 15 degrees, and I tried changing that to 11.5. And I tried the other two motor settings ie Normal, Special 1, Special 2. I have no idea what the other two setting are, but they made no difference either.

Thank you for your time,
Jay

The 35-30x1100kv motor is well within the limit of the 40amp esc... it's max amps is around 25amps... on the turnigy 40amp esc it should be set to high timing...

What prop were you using?

SK

MS_in_NY
01-28-2010, 02:48 AM
The most likely explanation is you're running too big a prop.

......Mike

ministeve2003
01-28-2010, 02:53 AM
Here's a couple sheets from drivecalc to give you an idea of what it should be,

SK

givmeasmoothy
01-28-2010, 03:16 AM
those charts are out of my league dont understand any of it mini steve. lol hey nitro finally got back with me i think they are ganna send me that stick mount.

ministeve2003
01-28-2010, 03:29 AM
Just look at the basics of that chart... at the bottom...

With that motor, 2200mah pack, and prop, it will tell you amps, Watts, volts, and the really good info ... Thrust, and pitch speed...

That motor looks best around 20-22 amps... you can prop around that for more thrust, or more pitch speed (faster)

SK

ministeve2003
01-28-2010, 03:32 AM
the props I suggested are apc 9x7.5e or 10x7e, or for more thrust for 3d try an apc 11x4.7sf

The smaller prop will give you less thrust, but once it gets going, will give you an overall faster plane...

SK

jaycook777
01-28-2010, 07:08 AM
Wow, you guys are great! Thanks for the quick replies. Those data sheets are awesome, I didn't know about the Drive Calculator software. I just went to his site and plan on downloading and playing with it.

I am glad I am using Eagle Tree's data logger, it is showing me that you guys are correct. Too large of a prop. I am building the E-flite Mini Funtana X. E-flite said to use a 12X6 prop.

My data shows that my motor is generating 380 watts compared to the 148 in the Drive Calc data with the 10X7 prop. That's more than twice as much! No wonder it's getting hot.

My amps were 37 where it should only be 21.

I wonder why E-flite wants a 12X6 prop?

Thanks again everyone. You've just alleviated my frustration.

I'll play around with it tomorrow and let you know the outcome.

ministeve2003
01-28-2010, 07:13 AM
My amps were 37 where it should only be 21.

I wonder why E-flite wants a 12X6 prop?

Thanks again everyone. You've just alleviated my frustration.

I'll play around with it tomorrow and let you know the outcome.

That's because the "eflite motor" is completely different, and I think it's KV is 910 or 1020...)

SK

ministeve2003
01-28-2010, 07:20 AM
My data shows that my motor is generating 380 watts compared to the 148 .

your Looking at the wrong number... that's 227 input... compared to 380....not 148 (output) ... your eagletree logs the input watts...

SK

givmeasmoothy
01-28-2010, 01:24 PM
I know this is a little off subject but how hard is it to program your esc

jaycook777
01-29-2010, 04:08 AM
I bought the Turnigy programming card. It makes it even easier. But using the specified manner in the instructions is easy too, just a little more time consuming having to listen to all the beeps.

jaycook777
01-29-2010, 04:21 AM
Well, I ran the motor with a 9X7e prop (the hobbyshop didn't have a 7.5), I ran it wide open for the duration of the battery and it never over heated!

I have a lot to learn about these model motors and speed controllers. I thought the E-Flite motor was close to my Turnigy, but like you posted earlier, E-Flite's is 1020kv.

I work as a Journeyman Electrician, but this topic is more into electric motor engineering, and this stuff really interests me.

I look forward to finding out the how and why the E-Flite motor is so much different.

Thanks again guys. :D

groundrushesup
01-29-2010, 05:52 AM
Well, I ran the motor with a 9X7e prop (the hobbyshop didn't have a 7.5), I ran it wide open for the duration of the battery and it never over heated!

I have a lot to learn about these model motors and speed controllers. I thought the E-Flite motor was close to my Turnigy, but like you posted earlier, E-Flite's is 1020kv.

I work as a Journeyman Electrician, but this topic is more into electric motor engineering, and this stuff really interests me.

I look forward to finding out the how and why the E-Flite motor is so much different.

Thanks again guys. :D

Just a thought - something to remember - every 2 inches o prop diameter effectively doubles your thrust and consequently your amp draw rises in a similarly exponential fashion.

a rough way to compare two props is to use the equation

(D^3)P * Sqrt(n-1) where D is the prop diameter, P is the pitch, and n is the number of blades (easy, because we have two blades, so 2 - 1 = 1, and the square root of 1 is.... Tada! 1!). Seems complicated but it ain't really.

12x6 would be

12x12x12x6*1 = 10368


The stock Corsair prop is 9.5 x 7.5, so

9.5x9.5x9.5x7.5*1 = 6430

relative to eachother, the loading is quite different - in fact, if you divide 10368/6430 (1.6124) you'll notice that the 12x6 is loading your motor by 60% more than the stock prop. That's a big load lol

Again this is a rough calculation, but it is handy when you want to change diameters/pitch on your props - all you need to do to guarantee you aren't over-propping when you change is to first calculate for a known prop loading (one that works for your setup within the system's limits) and then calculate the proposed pitch/diameter changes. when the two results are relatively close you can be sure the prop will not cause any damage to the power train. if you are willing to deal with a little extra math, this is also a good way to compare the loading of a 2-blade prop with a 3- or 4- blade prop if you were looking for a more scale setup.

FWIW. Hope I made some sense, it is late... ;-)

GRU

capn chaos
04-20-2010, 01:01 PM
Welcome to Watt Flyer Provence (and a belated welcome to Jaycook 777)
All of the above is extremely good advice and helps with taking the "mystery" out of electric flight. It will always be a matter of juggling the "pieces", motors, batteries, ESC's(and BEC's) Props etc to your flying programs. Tweaking props will give either more thrust or more speed but rarely succeed in gaining in both directions. I don't believe I saw mention of Wattmeter above and if it was mentioned, I totally second that.
A wattmeter hooked up inline with battery ESC will immediately tell you if you are in the specs of motor, ESC and battery abilities. It costs about the same as an ESC motor combo but will save many of these from frying. No more guess work and will confirm motor calcresults in case you pumped in some wrong numbers.
Again, Welcome to WF and keep us all up to date on progress.
Capn Chaos