Does heat affect the power of an electric motor?

[Offroader]

Couldn't locate anything specific. But when the hub motor starts heating up and especially starts to get pretty hot like 130c. Does this affect the power of the motor?

I could swear that the motor feels a slightly less powerful as the temps start climbing.

 

[r3volved]

I know resistance increases with heat...probably frocks with the field dynamics too.

 

[DAND214]

How about some more inf.
Motor, battery, controller, wheel size, wieght and terrain.

130c is HOT. How long does it take to get that hot and has it been that from the first install?

Dan

 

[Offroader]

I'm running a cromotor v3 18s lipo or 73 volts off the charger set at 60 battery amps maybe 130 phase amps. Cycle analyst shows 4300 watts at max.

I have 2.7KW of battery capacity so I have no problem heating this motor up. It started to get hot recently when running it during the summer, but I only finally wired in my temp probe so I am not sure how hot it got during the winter.

I had it up to 150c after a hard climb and at that point it has noticeable loss of power. But it all goes away after I let the motor cool.

So I am curious how heat exactly affects electric motors.

 

[Miles]

So I am curious how heat exactly affects electric motors.

As well as the resistance of the copper increasing, the magnets weaken, which means you need a higher current per unit of torque.........................

 

[John in CR]

Not only does getting it hot like that noticeably affect power temporarily, but if you keep doing it the power potential will go to 0.

 

[Futterama]

The magnets will demagnetize at elevated temperatures, the max temperature for reversible demagnetization depends on the magnet grade. For neodynium, here is some reading: http://www.kjmagnetics.com/blog.asp?p=temperature-and-neodymium-magnets

Quote from above link regarding a grade N42, D82 magnet:

Above 80°C, the magnet begins to irreversibly demagnetize.

 

[John in CR]

The magnets will demagnetize at elevated temperatures, the max temperature for reversible demagnetization depends on the magnet grade. For neodynium, here is some reading: http://www.kjmagnetics.com/blog.asp?p=temperature-and-neodymium-magnets

Quote from above link regarding a grade N42, D82 magnet:

Above 80°C, the magnet begins to irreversibly demagnetize.

The quality of the magnets will vary by manufacturer, though I doubt even one that uses the cheapest possible parts such as Crystalyte would use magnets that start permanently degrading at 80°.

It's not just about the magnets, though the at least temporary flux reduction with temperature along with less current getting thru the copper would be what you can easily feel while riding, some use cheaper glue for the magnets or cheaper wire with lower thermal ratings.