Over heating esc?


Well-known member
Noob question. How does one determine if an esc is overheating? I am flying a ARC Pirates Eazy, fairly small aircraft, smaller that the TT. I am running it on a DYS Samguk 2206 2400kv motor with a 5x4x4 prop and a 30a Emax BL Heli esc. I maidened it the other day on 3s and it flew awesome. Towards the end of the 2nd battery, it started to sputter, like it was misfiring and went down to maybe 20% power. I didn't think to much into it as i was at the end of the battery anyway. Well, today, i decided to try it on 4s. But this time, it did the exact same thing but at less than half the battery used, and did it on all 3 batteries. I landed it, felt everything for heat, everything was cool except the esc. It was a tad hot but i could hold it easily in my had. After waiting a minute, i threw her back out and it flew fine for about 30 seconds and started doing it again, sputtering around not going over 20% throttle.

Now, looking at the specs, the motor on 3s with that prop only draws about 19a. With a 30a esc, it shouldn't have any problem at all. Heck, even on 4s its only drawing about 28a. With an esc that is 2-4s compatible and does 30a continuous and up to 40a burst, how would this cause me issue? In theory, i should be able to run 4s with that prop and full throttle till the battery dies before i have issue.

Does this sound like the esc is overheating? If so, is there a solution to this issue other than cutting vents into the fuselage?


Master member
It could certainly be the ESC over heating. Some just cut out others reduce the power. If you continue to fly it will cool, reset but then over heat again. If an ESC starts to give odd effects land asap!
As a rule an ESC generates as much heat as the motor but of course it does not have the benefit of rotating parts to swirl the air about so a positive airflow around it is important.
It can be is unwise to run an ESC at or near its full capacity as it may only be rated for 10 seconds, Running at 2/3 capacity and with positive cooling is advised.


Old and Bold RC PILOT
I had a motor do the same thing and it just got progressively worse. In my case I was about to toss the ESC when I noticed that the colour of the windings on the motor was not uniform. Some of the Poles were still quite bright whilst others were showing discolouration.

I pulled the motor apart and found that I had a few poles that had broken wires. Each of the motor leads actually connected 3 or more of the coil wires and a couple had broken. This gave an intermittent power output from the motor without the motor actually ever refusing to start and turn.

After repairing the windings I reassembled the motor and it is as good as it ever was. The ESC was blameless!

Just what I discovered and repaired!

Have fun!


Active member
You might need to put an air scoop in the front to let air in, don't forget the exit hole. Also note, some esc's have a thermal switch that reduces current flow.


Wake up! Time to fly!
You are not using too long screws and they are penetrating the mounting plate and touching the winding's are you? this is common with quads and that causes heat and rpm issues big time.


Wake up! Time to fly!
You are very welcome mate. Just get us some video of your success in flight when you can. That what powers our forums.