Motor, ESC, Battery temps, whats good, whats not?

[Varooom]

Been watching many YouTube videos lately. Watching guys change props and then check motor, ESC, and battery temps but they never say whats good and what is not.
What I would like to know is what is good operating temp for the motor, ESC and batteries?
What's the "oh its getting a little too warm" temps?
And finally, what is oh s#it, its too hot temps?

Thanks for your time,
Varooom

BTW: connectors and wires too.

[Xrayted]

Most ESCs have a thermal shutdown around 100C/212F. A brushless motor can get up to 175F and still be normal depending on the ambient air/water temps at the time, but is starting to get too hot once you get near 200F. Larger motors with more mass can tolerate heat better than smaller motors can.

You need to measure using a proper IR temp gun, as human hands are terrible at determining what "too hot" is by feel. For example 145F will cause most people to pull their fingers back very quickly, but 145F for a motor is completely normal, and actually running cool. You also wouldn't touch the engine on your car either without being burned, but that doesnt mean the car is running hot, so its the same with our electronics.

Batteries on the other hand are too hot if they are uncomfortable to hold in your hand after a hard run. You are in the damage range once they get up in the 130 zone. Lipos are happiest with the lowest IR in the 80-100F range. There is also the other side of the scale, where lipos can easily be damaged if trying to pull too much current from them when too cold, so they need to be warmed up in Winter climates to reduce the internal resistance so they dont become permanently damaged and puff

[Varooom]

Thank you Xrayted!
Thats what I needed to know.
Thank you,
Varooom

[T.S.Davis]

Neodymium magnets, which are the most common in motors. lose some of their magnetism permanently at about 176 degrees. My recollection. Someone will know the real number here. This does not vary based on size. 200 degrees will result in a weaker motor for subsequent runs.

Get a cheesy temp checker from Harbor Freight to be sure. Once you've been doing it a while, you get good with the hand test. I can usually guess within 5 degrees. Ridiculous way to check in truth. haha HF sells a tiny one for like $20 or something. Checking with my hand is dumb........but stilllll do it.

[Xrayted]

Quality motors use magnets that are rated in the 150C/300F range. There would be a lot of ruined motors on a weekly basis across the entire RC industry if running at 176 killed the motor, as that is completely normal operating temp for RC heli flights all day long on every flight, and those flight last longer than boat runs do. Ive been flying E helis for nearly 20 years, and have motors that are many years old that see those temps or more on every single flight. The magnets are all rated to 150C/302F per the manufacturer for the motors in those models, but of course that's not a challenge to do so!

One of my helis is a custom speed competition model where the motor is in a completely closed fuselage that runs over 150MPH. It pulls hundreds of amps in the run, and the motor gets neat 200F on every flight because of no airflow, yet there is zero loss of performance and top speed after more than 7 years of punishing its motor.

I would agree that some of the cheap chinese Amazon motors, or RTR boats may cheap out and use lower quality magnets, but even the cheap Dynamite motors (HW rebrand) in my Miss Geico uses magnets that are rated for 176F. This is why I always use 175F as the upper "normal" limit for a brushless motor, as things start getting sketchy once you cross that value and start approaching 200F. My cheap Dynamite motors are still running strong after 3 years, and they average temps in the 175 range every single run just like all my boats do since I like to run 6+ cells on all of them.

Im not seeing any difference at all between my boat motors and my heli motors as far as temps or motor performance/longevity goes, but of course yes, lower temps are always better if possible

[T.S.Davis]

Made me do some more reading. Thank you sir. Always a good thing. Fascinating stuff.

Found this gem on google of all things.

As a rule Neodymium Magnets lose 0.11% of their magnetism for every 1 degree Celsius rise in temperature. This small loss is fully recoverable on cooling, providing that the maximum operating temperature is not exceeded.

Apparently there are different grades of Neodymium magnet. Did not know that. None of the OSE listings show which type neo the motors are constructed with. Might be trade secret kind of stuff. None of the motors give a temperature rating either. At least not here on OSE.

Kept reading. Learned this....

For a standard neo magnet, the temperature where permanent demagnetization starts to occur is 175 degrees. Then the highest temperature neo is a type AH. That can withstand 446 degrees with no damage. Holy crap! You still lose magnetism with increased temperature but it isn't permanent until you reach the magic temp for each type of magnet. So power loss due to heat....... but not permanent damage. There's a whole range in between the standard and high temp neo that motors could be made with. Getting a straight answer from a motor maker might be tough.

It's possible that I was told there was a 175 degree damage point some time ago due to us never being sure which motors had which magnets. Especially in the Hacker/Aveox/Fiageo days.

[fweasel]

Made me do some more reading. Thank you sir. Always a good thing. Fascinating stuff.

Found this gem on google of all things.

As a rule Neodymium Magnets lose 0.11% of their magnetism for every 1 degree Celsius rise in temperature. This small loss is fully recoverable on cooling, providing that the maximum operating temperature is not exceeded.

Apparently there are different grades of Neodymium magnet. Did not know that. None of the OSE listings show which type neo the motors are constructed with. Might be trade secret kind of stuff. None of the motors give a temperature rating either. At least not here on OSE.

Kept reading. Learned this....

For a standard neo magnet, the temperature where permanent demagnetization starts to occur is 175 degrees. Then the highest temperature neo is a type AH. That can withstand 446 degrees with no damage. Holy crap! You still lose magnetism with increased temperature but it isn't permanent until you reach the magic temp for each type of magnet. So power loss due to heat....... but not permanent damage. There's a whole range in between the standard and high temp neo that motors could be made with. Getting a straight answer from a motor maker might be tough.

It's possible that I was told there was a 175 degree damage point some time ago due to us never being sure which motors had which magnets. Especially in the Hacker/Aveox/Fiageo days.

Good info dig there

[T.S.Davis]

Good info dig there

Yeah, I guess the right answer on motor temperature is......it depends. Clear as mud.

[Xrayted]

Yes, and in retrospect my original reply was too broad, and I should have said "it depends on the motor" rather than a sweeping statement considering the difference in magnets that can be used. I use the 175F value simply because that's the lowest number that I have ever seen reported by a manufacturer, that is IF you can actually find this info, and that is not always easy as you have stated.

The outrunner motor brand I use for my helis publish this info, and it would be nice if everyone did. They use NSH neodymium material type magnets which are rated to 150C/302F. The lowest rating is with N classification magnets which is 80C/176F, so if you can manage to find what class magnets are used in the motor, you can easily determine the heat rating

I have bought loose magnets from these guys before to make custom quick release canopy mounts for my helis, and they have a lot of geeky info regarding neodymium magnets and how temps will effect them. Its not specific to any particular motor brand, but interesting stuff in general, including the heat tables for the various magnet classes.

https://www.kjmagnetics.com/blog.asp?p=temperature-and-neodymium-magnets#section-1

[T.S.Davis]

For years I told guys 167 degrees max but I had no data. That was just some crap somebody told me one time and it stuck with me forever.

Yesterday we broke the ferrite magnets in our retrieve motor. Wish those were neo. Total rubbish in those things. One brush was half gone and the other was in good shape. Ugh. Like working on dinosaur bones.