Safe Maximum Temperature for Brushless Motors

[RustyUs]

Since the question came up recently on another thread, and I did not see any specific thread on the subject.

I know what my normal/cut off temperatures are and how/where I go about getting them. I've always tried my best to not let my motors go above 180°F (82.22°C) even though Castle Creations stated early on for their brushless motors not to exceed 200°F.

On Castle Creation's website, they now have this:

It's important to consult the manufacturer's specifications and guidelines for the motor, ESC, battery, and other components to ensure that you stay within their recommended current limits. Additionally, monitoring the temperature of these components (Keep ESC and motor temps UNDER 200°F, preferably 180°F or lower; LiPo batteries should not exceed 130°F) during operation can provide a practical indicator of whether excessive current is being drawn, as overheating is often a visible symptom of this issue.

**It is always useful to have one of these infrared thermometers on hand, they are specially designed for use with R/C engines, motors, battery packs, battery chargers, electronic speed controllers, as well as hundreds of other applications. To use, simply aim the infrared thermometer at the target and press the measurement button to quickly and easily display the surface temperatures.

From Hobbywing on the subject:

What is the ideal temperature of ESC and Motor? - Avoid overloading your gears.​

6 years ago Updated
The most common reason for your ESC / Motor damage is found by "overloading"

It is hard to accurately check the "load of a vehicle system, but there is a simple method.

Measuring the temperature of ESC and motor.

If the ESC temperature (measured from outside at the hottest position) is over 85 degree (for low-cost thermal instrument with low accuracy) or 90 degrees (for high-cost thermal instrument with high accuracy), or the motor temperature is over 90 degree or 100 degree, your system configuration must be changed immediately that a load of vehicle is too heavy for your ESC or motor.

In such a case,

change your gearing ratio by using a smaller pinion or bigger spur gear by one. Check the temp again after running a few laps until you find the perfect ratio. "Stock gearing" does not mean your system with upgraded electronics works perfectively.

Airplane / Heli
change PROPS SIZE, by sizing down to smaller propellers. timing set to 0, Reduce voltage, Check the temp again after running a few minutes until you find the perfect size.


FPV
change PROPS SIZE, reset betaflight, no timing, Reduce voltage, Check the temp again after running a few minutes until you find the perfect size.

 

[Littlemotor]

Wow… My Tekin stuff wants me to keep it under 185deg. Hasn’t been a problem obviously lol..

 

[WickedFog]

Wow… My Tekin stuff wants me to keep it under 185deg. Hasn’t been a problem obviously lol..

Yeah, HW has some crazy temps they claim their motors can handle. I don't go above 170°F on anything, and if I hit 160°, I am keeping a close eye on things. If it hits 160, all it takes halfway through a run is to pick up some dirt, a stick, or whatever to ramp the temp up. I like a little cusion there.

 

[Littlemotor]

Yeah, HW has some crazy temps they claim their motors can handle. I don't go above 170°F on anything, and if I hit 160°, I am keeping a close eye on things. If it hits 160, all it takes halfway through a run is to pick up some dirt, a stick, or whatever to ramp the temp up. I like a little cusion there.

Agreed. Electronics aren’t cheap, and no matter the reputation of the product-I always gear accordingly. Cool electronics are happy electronics.

 

[Greywolf74]

The maximum safe operating temperature for brushless motors is generally around 170°F (77°C). Exceeding this threshold can lead to several issues:

• Magnet Degradation: Elevated temperatures can cause the motor's magnets to lose their magnetic properties, leading to reduced torque and efficiency.
• Insulation Breakdown: Excessive heat may damage the insulation on the motor windings, resulting in short circuits or complete motor failure.
• Bearing Wear: High temperatures can cause lubricants in the motor bearings to break down, increasing friction and wear.
• Adhesive Failure: Overheating can weaken the glue securing the magnets, potentially causing them to detach and leading to motor failure.

 

[CertifiedMike]

I see ppl thinking about a max temp.
I am thinking these motors are like cooking a turkey.
Once they get hot, they continue to cook! The temps internally prob got way higher than outside temp readings too.

 

[Greywolf74]

I see ppl thinking about a max temp.
I am thinking these motors are like cooking a turkey.
Once they get hot, they continue to cook! The temps internally prob got way higher than outside temp readings too.

This is true, but the 160-170F range is talking about can temps. Fans help to keep internal temps from rising like crazy once the RC comes to a stop. Let that fan blow on it for a good 30 seconds or so before turning it off.

 

[Cranberry Juice]

I have an infrared temp gun. Works real well, just push a button and read the temperature.