7.5KW 60mph+ build

apprisco

10 mW
Joined
Feb 4, 2021
Messages
31
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Absolute unit of a scooter, each part of the assembly either purchased separately, or machined & welded from aluminum.
The problem here is that I need to somehow actively cool these motors: just recently, I burnt out both wheels due to overheating. Luckily these are quite easy to take apart and rewind, so the motor is back in action.
Not sure what I can do at all to cool these down, it's not like I can just get some hubsinks on them :(
 
Stator-aide should help a ton. It's a ferro fluid that improves thermal coupling from the stator to the casing shell of the motor.
 
Yeah, I'm already prepping for statorade on the new motors, but I'm not convinced. It helps move heat away from the core to the casing, but what will cool the casing itself? Thermodynamics isn't magic. I can move the heat around but I need to get rid of it somehow, not just move it.
 
apprisco said:
Yeah, I'm already prepping for statorade on the new motors, but I'm not convinced. It helps move heat away from the core to the casing, but what will cool the casing itself?

The thermal gradient between hub shell and air is directly proportional to your ability to reject heat. The hotter the external surface exposed to air, the more quickly you can be rid of the heat.

Make no mistake, you can only move heat around. You want to move it quickly to the outside surface so you can move it in turn to the ambient air.
 
apprisco said:
~ but I'm not convinced.

You can spray water on the shell.
 
I'm currently planning on modding the motor casing itself and adding some heat sinks on it to cool it better, we will see. The issue is that last time, even the motor casings were untouchably warm, so I need to cool them for sure.
 
larsb said:
i'm suprised no one has stated the obvious yet: these motors get too hot because they are to small to do 7.5kW efficiently. Switch motors.

Any motor that fits in a wheel, that fits in the frame or fork of that riding toy, won't tolerate 4kW each.

I was half looking forward to the road pizza recipe.
 
obviously everyone's experience is different, but my guess is you're going to get it up to, or near 60mph, be glad you did so you can brag about it to your friends, and then never elect to do it again. Also, make sure your speedometer is very far forward because you are not going to want to look down at that speed. Wheel wobble, lousy steering due to short lever arms, lousy vibration suppression because of small wheels and light weight -- seriously, youre really unlikely to enjoy it much.

you will however probably have a great time with the high amount of torque at lower speeds.
 
Going 60+ mph even on a downhill bicycle frame is super sketch. Doing this on a scooter is literally Russian roulette. Do you wear a full motorcycle gear or what? Have you ever seen road rash in real life? I would guess not.

As far as cooling the hubs F/F well definitely help and especially if you can figure out a way to install heat sinks.
Also keep an extra bottle of really cold water or maybe in a camel pack or something that definitely helps to cool the motor off. I typically will roll the motor down into a creek bed. That being said my hub motors are varnished on the inside so I’m not too concerned with the water/moisture.
 
I would say 80mph on a scooter starts to feel overly sketch, but 60mph on a scoot is not too bad.

Eric has a dual adapto apocalypse scoot on 20s running 7-8kW to each hub, and it gets to 60mph so quickly you barely have time to be scared because you're too focused. 😉

And yes I wear full motorcycle gear for that.
 
liveforphysics said:
Eric has a dual adapto apocalypse scoot on 20s running 7-8kW to each hub, and it gets to 60mph so quickly you barely have time to be scared because you're too focused. 😉

Do you have info/photos/videos of this? That sounds hilarious.
 
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