12 kw rc motor

Hmm i will be extremely careful with that Biff! Thanks for your experience.

Does anyone know what the practical voltage limit these can be run from is? I was wanting to use 36s... Will that just kill efficiency/destroy bearings?
 
tostino said:
Hmm i will be extremely careful with that Biff! Thanks for your experience.

Does anyone know what the practical voltage limit these can be run from is? I was wanting to use 36s... Will that just kill efficiency/destroy bearings?
Click to expand...
Depends on how you wind it.
Aim for ~6000 rpm and no higher then 7500 rpm with the old one I have the skirt bearing cant spin any faster!
 
Ahh hrmm, so I guess there is just one stock winding, and i'd have to re-wind the motor for my rpm needs?

What is stock wound for K/V wise?

So really you can't go higher than 7,500 rpm? hmm alright... is it just that one bearing stopping it?
 
tostino said:
Ahh hrmm, so I guess there is just one stock winding, and i'd have to re-wind the motor for my rpm needs?

What is stock wound for K/V wise?

So really you can't go higher than 7,500 rpm? hmm alright... is it just that one bearing stopping it?
Click to expand...
The new version of the motor has a smaller skirt bearing that can spin faster!
 
Using multiple controllers is quite possible and has been done before. That guy who made an axial flux motor out of plywood used no less than seven RC controllers for testing, and later again on the finished motorbike after the kelly controller had burned out. As it seemed, he let each of them individually power three coils (there where 21 in total), instead of sharing parallell wound coils. This gives less interference for the sensorless controllers but may cause assymetric loading. When using sensored controllers however, parallell windings should work just fine. So splitting the strands in a finished winding will probably work, just make sure to check for shortcuts and direction of rotation.
 
markobetti said:
mechanical limit of bearing is 12 000 - 14 000 rpm :)
Click to expand...
Im a little worried about 14000 rpm out of one of these monsters!!!
We should calculate the tensile force on the skirt at that rpm!
 
Arlo1 said:
markobetti said:
mechanical limit of bearing is 12 000 - 14 000 rpm :)
Click to expand...
Im a little worried about 14000 rpm out of one of these monsters!!!
We should calculate the tensile force on the skirt at that rpm!
Click to expand...


I haven't done a careful calculation, but I am worried about core losses at above 7000 RPM. I think the available torque will significantly drop as the core losses start to increase, so you won't actually be able to get much power out of the motor when spinning that fast. The Videos that I have seen sofar suggest that the core loss is still rather low up to 6000 RPM, but at some speed it is going to become a real problem.

-ryan
 
Biff said:
Arlo1 said:
markobetti said:
mechanical limit of bearing is 12 000 - 14 000 rpm :)
Click to expand...
Im a little worried about 14000 rpm out of one of these monsters!!!
We should calculate the tensile force on the skirt at that rpm!
Click to expand...


I haven't done a careful calculation, but I am worried about core losses at above 7000 RPM. I think the available torque will significantly drop as the core losses start to increase, so you won't actually be able to get much power out of the motor when spinning that fast. The Videos that I have seen sofar suggest that the core loss is still rather low up to 6000 RPM, but at some speed it is going to become a real problem.

-ryan
Click to expand...

In other words, at 80V and some 220A it could produce some 16kW power (with some slight losses from the mathematical 17.6kW) continuous. Has anyone done some calculations about short bursts of current, lets say 550A for some 2 minutes or 660A for some 10 seconds..?
 
dangerzone said:
Biff said:
I haven't done a careful calculation, but I am worried about core losses at above 7000 RPM. I think the available torque will significantly drop as the core losses start to increase, so you won't actually be able to get much power out of the motor when spinning that fast. The Videos that I have seen sofar suggest that the core loss is still rather low up to 6000 RPM, but at some speed it is going to become a real problem.

-ryan
Click to expand...

In other words, at 80V and some 220A it could produce some 16kW power (with some slight losses from the mathematical 17.6kW) continuous. Has anyone done some calculations about short bursts of current, lets say 550A for some 2 minutes or 660A for some 10 seconds..?
Click to expand...

The "slight losses" in the calculation are 1.6kW which is about 10% loss. To give a visual on how much heat that is, it is about the same amount as 26 - 60W light bulbs. At that heat production, you would definatly need that liquid cooling system working very well. I expect the losses (this is just a guess, I haven't run it through any simulation) at 80V, 220A to be slightly less than that, maybe 6% loss, wich would only be around 1kW of heat production, which would still need liquid cooling, but you might not be pushing the limits of the coolant design.

-ryan
 
Biff said:
dangerzone said:
Biff said:
I haven't done a careful calculation, but I am worried about core losses at above 7000 RPM. I think the available torque will significantly drop as the core losses start to increase, so you won't actually be able to get much power out of the motor when spinning that fast. The Videos that I have seen sofar suggest that the core loss is still rather low up to 6000 RPM, but at some speed it is going to become a real problem.

-ryan
Click to expand...

In other words, at 80V and some 220A it could produce some 16kW power (with some slight losses from the mathematical 17.6kW) continuous. Has anyone done some calculations about short bursts of current, lets say 550A for some 2 minutes or 660A for some 10 seconds..?
Click to expand...

The "slight losses" in the calculation are 1.6kW which is about 10% loss. To give a visual on how much heat that is, it is about the same amount as 26 - 60W light bulbs. At that heat production, you would definatly need that liquid cooling system working very well. I expect the losses (this is just a guess, I haven't run it through any simulation) at 80V, 220A to be slightly less than that, maybe 6% loss, wich would only be around 1kW of heat production, which would still need liquid cooling, but you might not be pushing the limits of the coolant design.

-ryan
Click to expand...

True, if it were only heat induced but I was referring to losses due to transmission and other losses, the amount of horsepower on the rear wheel and tire of any bike is always a bit weaker than the power on the shaft side. And frankly, 1.6kW of heat would melt the motor itself, which would be irrational. If I remember correctly the efficiency of the motor is somewhere around 95%-96% so the heat would be even less in the 800W range. With decent air cooling, that is ok for continuous use. Push it a bit harder, twist the wrist, and that water cooling would be very useful. That is why I ask how does the Colossus behave with higher current bursts, the 60 and 120 seconds at 550A and 10 seconds at 660A seem like a good benchmark test. Then do the same test under different loads to see the heat difference and how much does the little monster handle for real.
 
Biff said:
dangerzone said:
Biff said:
I haven't done a careful calculation, but I am worried about core losses at above 7000 RPM. I think the available torque will significantly drop as the core losses start to increase, so you won't actually be able to get much power out of the motor when spinning that fast. The Videos that I have seen sofar suggest that the core loss is still rather low up to 6000 RPM, but at some speed it is going to become a real problem.

-ryan
Click to expand...

In other words, at 80V and some 220A it could produce some 16kW power (with some slight losses from the mathematical 17.6kW) continuous. Has anyone done some calculations about short bursts of current, lets say 550A for some 2 minutes or 660A for some 10 seconds..?
Click to expand...

The "slight losses" in the calculation are 1.6kW which is about 10% loss. To give a visual on how much heat that is, it is about the same amount as 26 - 60W light bulbs. At that heat production, you would definatly need that liquid cooling system working very well. I expect the losses (this is just a guess, I haven't run it through any simulation) at 80V, 220A to be slightly less than that, maybe 6% loss, wich would only be around 1kW of heat production, which would still need liquid cooling, but you might not be pushing the limits of the coolant design.

-ryan
Click to expand...

-spot on biff,
we've done a good bit of testing with this and came up with exactly the same numbers, 80v, 220a, 6000rpm, gets you about 94% efficiency and 16kw of power (this is the actual peak efficiency point for 80v running) -depending on the vehicle weight etc you could probably run it to this to accelerate without liquid cooling, but with 1kw of heat to dissipate, would be best liquid cooled for continuous use.

the no load consumption at 6000 was quite low, so you could maby push on to 7000 to 8000rpm as a maximum? -beyond which core losses will get out of hand.

and 660a for 10 seconds? i say yes -maby, you will have over 4kw of heat so start with a cold motor as thermal mass is all you have going for you, it could make about 50kw and still be over 90% efficient if it doesnt saturate, i reckon the motor could make this power for a few sweet seconds or so..
-silliness though really, like putting 15kw into an X5.
 
toolman2 said:
and 660a for 10 seconds? i say yes -maby, you will have over 4kw of heat so start with a cold motor as thermal mass is all you have going for you, it could make about 50kw and still be over 90% efficient if it doesnt saturate, i reckon the motor could make this power for a few sweet seconds or so..
-silliness though really, like putting 15kw into an X5.
Click to expand...
But.... Thats How I Roll.............. :mrgreen:
 
What If I rewind it? And get more copper fill? I want 80 KW!!!!!!
 
toolman2 said:
-spot on biff,
we've done a good bit of testing with this and came up with exactly the same numbers, 80v, 220a, 6000rpm, gets you about 94% efficiency and 16kw of power (this is the actual peak efficiency point for 80v running) -depending on the vehicle weight etc you could probably run it to this to accelerate without liquid cooling, but with 1kw of heat to dissipate, would be best liquid cooled for continuous use.

the no load consumption at 6000 was quite low, so you could maby push on to 7000 to 8000rpm as a maximum? -beyond which core losses will get out of hand.

and 660a for 10 seconds? i say yes -maby, you will have over 4kw of heat so start with a cold motor as thermal mass is all you have going for you, it could make about 50kw and still be over 90% efficient if it doesnt saturate, i reckon the motor could make this power for a few sweet seconds or so..
-silliness though really, like putting 15kw into an X5.
Click to expand...

Maybe, but some of the guys here on ES have done that... :D Aren't most of the motors tested that way, pushed to the limits and then the engineers set a 'normal' range and a 'redline' one..? ;)

Anyway, I guess 16kW is ok, if more power is needed there is always the option of stacking two Colossuses in series yet I wonder how would the controllers have to be arranged..?
 
Arlo1 said:
What If I rewind it? And get more copper fill? I want 80 KW!!!!!!
Click to expand...

Even if you rewind it with silver wires I somehow doubt it could be pushed to a 80kW 10 second burst, isn't that a bit much..? 80V and 1000A, huh..? Copper would melt, definitely.
 
Arlo1 said:
What If I rewind it? And get more copper fill? I want 80 KW!!!!!!
Click to expand...
I've done the calculations, and pretty much any way you look at it once you get above 60% fill factor or so, you should really focus your efforts on trying to get better cooling to increase your power. Think dry ice in a fire-extinguisher type thing forcing cold air past the narrow space between coils. Even the liquid cooling on this thing won't be able to handle high power because there isn't that much surface area to get the heat out. I if you are hoping to get about 8seconds out of this motor, maybe 35-40kW, but that also depends on the saturation of the core and thickness of the magnets, I haven't run a detailed simulation on this motor so again, these are just guesses.

-ryan
 
dangerzone said:
I somehow doubt it could be pushed to a 80kW 10 second burst
Click to expand...
He is just kidding.. anyways at the size and weight of this motor if one seriously needs 80kW, just use 3 or 4 of them.
 
Im just going to run it as hard as I can the controler is still the issue!

Im thinking 3 24 fet custom built controlers at 100 volts!
The question is do I wind it in series as a 9 phase or paralel winds as a 3 phase
I am also thinking even if I did spike 40-60kw it will be for such a short time because the bike will flip over or I will die because of the speed it wont be an issue!
All I am trying to do is build a retarted YSR50 so I can have fun and scare little children and old women!
 
Arlo1 said:
Im just going to run it as hard as I can the controler is still the issue!

Im thinking 3 24 fet custom built controlers at 100 volts!
The question is do I wind it in series as a 9 phase or paralel winds as a 3 phase
I am also thinking even if I did spike 40-60kw it will be for such a short time because the bike will flip over or I will die because of the speed it wont be an issue!
Click to expand...
You and I seem to think alike! Your 3 controllers will prolly put out a bit more power total than my two (considering I went for 4115 fets), but the fet count is the same.
If you haven't seen what I want to do, my build thread is here: http://endless-sphere.com/forums/viewtopic.php?f=10&t=25063

I would think that 9 phase would give you smother operation, but i'm just talking out my ass on that one lol. I have no real clue :p.
Why are you planning on rewinding it? Is the factory wind that bad?

It seems like I have the same plan as you lol, I am fine with just being able to get a spike of like 40-50kw for a few seconds... I will already be at top speed in that short period of time if I can do that lol.

I'll just get a nice very oversized radiator to run the motor + controllers through at the same time if possible. I must buy!
 
http://endless-sphere.com/forums/viewtopic.php?f=10&t=18183

Thats my build. I am thinking I just want enough to be able to KILL collossus :twisted:
I am thinking I can fit 3 24 fet controlers under where the tank used to be!
I am aiming for 4 kw of lipo on the bike and on bord charging!
I will rewind it so we can fit more copper ALL mass produced motors have pour copper fill they need to be hand wond to make it as good as possible!
 
Just a thought from one ignorant about much about electric motors, would it be possible to cnc machine copper to perfectly fill the spaces?
 
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