Punx0r wrote:I'd be surprised if you'd done any damage at 70°C...
Can you check the KV of the motor? It should have risen if the magnets have lost any strength.
However, ferrofluids lose their magnetic properties at sufficiently high temperatures, known as the Curie temperature.
Doctorbass wrote:I have two brand new QS motor so if i can get a gaussmeter i will measure teh magnetic field and compare...
steveo wrote:How do you think this will compare vs the x5403?
50mm stator.. nice copper fill from what i've seen.. and it come up the 17.71kv version... and around 29lbs!
i wonder what the efficiency rating of a x5403 was?.. this seems to be around 90%.. .. i know my hub-monster according to johnincr is up to 94% efficient but around 60lbs with tire.
Yes, i cleaned the magnet with aceton and then isopropylic alcool.madin88 wrote:I wonder what paint you have used. Was ist the krylon deep black? Simply Krylon ultra mat flat black 1602, 97% absorption on large spectrum
Doc, maybe you remember that i also have painted the entire inner surface of one MXUS 3000 V2 motor and the parts i have also put in the oven for drying. Back on the bike, the motor did overheat quicker than usually (especially when loaded high), because the magnets got weakened.
The temperature was set to 70-80°C, but as mentioned such regualtion is very inaccurate. Well that is sad that yours overheated and that you noticed permanent damage!... On my side, the Oven i have used is a special equippent with very accurate Honewell PID temp controller. The temp remained below 78 degree c ( i had set the shutdown alarm to 80 to be sure )
Did you have already compared the strength with the gaussmeter? not yet , i'm actually looking for a gaussmeter. at work we have one very professional, but i can't locate it
At that time i used a piece of metal and measured the force it takes to remove it from the magnets with a scale.
It wasn't that accurate, but the results did show reproducible lower strength. Yeah that good idea. But i think if i have mathetic field loss it should not be so high as it is right in the knee of the curve according to the 35HS spec sheet at 78 degree C.
In the end, the dry process in the oven of the rotor did not help anything i believe, because i could chafe off the paint from the magnets easy with my fingers
On the other surfaces the paint holds extremely well. I was surprised how well it hold on the strands of the windings. Yes you are right, and i remember that last time i painted the magnet on my previous motor, i applied a very thin layer of residual epoxy coming from the excess of sides of the magnet brick, amd applied it on all teh inner surface of the magnet witch helped the paint to stick on these. Then i applied the paint. Yes that paint stick very well on most surface including the winding
Did you do any surface preparation on the magnets?
DasDouble wrote:@Doc, could you please explain me why you have put that brown paper between your stator and the side plate of your motor? It looks like some classic baking paper which is used for making pizza..
spinningmagnets wrote:Doc, you have tried several coatings inside the motor to protect from rust. what brand of coating do you use now as the best?
madin88 wrote:I wonder if iron saturation can be measured with such gaussmeter?
About the magnetic field i always was the meaning it is strongest above the middle of the magnets, since between the magnets the fields are canceling out and doing not much (or nothing?) in view of torque.
Thats why weight optimized motors have a gap between the magents.
DasDouble wrote:spinningmagnets wrote:Doc, you have tried several coatings inside the motor to protect from rust. what brand of coating do you use now as the best?
Really good question. +1 Im interested too
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