How hot is too hot?

[mistercrash]

I recently went to 74V on my e-moped. Although I don't think that I'm having heat issues, I would like to get the expert's opinions on how hot the components can safely get before getting damaged. Mainly how hot can the controller's casing get? How hot can the motor windings get? How hot can the battery get and also how hot can the phase and power wires get. Any other opinions on some other components getting too hot is welcomed.

After a 14 km ride at mostly WOT, I took these temps:

- motor windings 240 degrees Fahrenheit
- motor end caps 135 degrees Fahrenheit
- controller case 125 degrees Fahrenheit
- phase wires 120 degrees Fahrenheit

If this has already been discussed in detail then I apologize, the search feature gave me hundreds of posts and threads that were not useful. If there is a thread that discusses the various max temps of EV components then please direct me to it. Thank you.

 

[Ypedal]

240f = 110c

that is the max i would allow, any much more and the varnish off the windings will start to cook and burn off then the motor fails.

the battery should remain cool, if it gets warm it's being stressed.

wires getting hot, easy fix, increase wire gauge..

controller .. i would keep below 60 celcius at all costs.. a bunch of components inside will be hotter than 60 if the outer shell is that hot...

 

[dnmun]

how did you determine the winding temp? have a sensor inside?

 

[arkmundi]

plus 2C and its all over for planet earth with post-threshhold run away and catastrophic climate change. so everyone get an ebike and throw those huge monstrosities called cars away. there's now barely enough time for a safe climate. only radical action to get us there. go deep-green, do resistance, hassel your family & friends, anything to get us where we need to be. change your life, walk the walk, ebike the bigE, model & demonstrate the new economy. be good.

 

[mistercrash]

how did you determine the winding temp? have a sensor inside?

I made holes in the end caps for ventilation so I can point the temp gauge right on the windings in a few spots around the motor. Good thing there's holes in those end caps or else I would've cooked that motor already.
This ride was basically a test to see how far I could push this moped before things get ugly. So I was out on stretches of road with hills and no stop signs to slow me down. I checked the temps a few times along the way. I was WOT most of the time on a 85 degree day which I won't do when riding normally around town so the temps should be much lower than what I noticed today.

 

[dogman dan]

You are seeing about the max on your motor. I've taken em hotter with predictable results, but I like to call 200F on the windings about the safe limit for real reliability. Others will say 300F, but by then you start cooking off hall sensors and browning the windings. At 451F you start igniting the strings that tie up the windings, and a bump can disconnect soldered connections. I have a motor running that survived that, but the windings are pretty black, and it's risking the burnt varnish letting the wires short. On that one the halls even survived, but I had to solder the phases back on.

In the desert heat, I've never cooked a controller. Just mount it where it gets wind and you should be ok unless you are running a high speed motor that's notorious for popping controllers. 5303 for example.

Phase wires will run much cooler if you make them bigger. You can just splice on fat wire 6" from the axle. The fat wire will act as a heat sink to some extent, and the thicker wire will not contribute to the heating. 12 guage is often enough, but some will put 10 or even 8 guage. It's a long run of wire usually, so the fatter the better.

Battery temp shouldn't be getting real hot. But 100F would not be considered unusual. The less it's heating up, the better it likes it though. On a lifepo4 battery, letting the bms have some cooling air is important. Don't smother a bms in an insulated bag in hot weather.