Depends on how you wind it.tostino wrote: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?
The new version of the motor has a smaller skirt bearing that can spin faster!tostino wrote: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?
Im a little worried about 14000 rpm out of one of these monsters!!!markobetti wrote:mechanical limit of bearing is 12 000 - 14 000 rpm
Arlo1 wrote:Im a little worried about 14000 rpm out of one of these monsters!!!markobetti wrote:mechanical limit of bearing is 12 000 - 14 000 rpm
We should calculate the tensile force on the skirt at that rpm!
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..?Biff wrote:Arlo1 wrote:Im a little worried about 14000 rpm out of one of these monsters!!!markobetti wrote:mechanical limit of bearing is 12 000 - 14 000 rpm
We should calculate the tensile force on the skirt at that rpm!
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
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.dangerzone wrote: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..?Biff wrote:
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
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 wrote: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.dangerzone wrote: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..?Biff wrote:
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
-ryan
-spot on biff,Biff wrote: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.dangerzone wrote: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..?Biff wrote:
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
-ryan
But.... Thats How I Roll..............toolman2 wrote:
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.
Maybe, but some of the guys here on ES have done that... 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..?toolman2 wrote: -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.
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 wrote:What If I rewind it? And get more copper fill? I want 80 KW!!!!!!
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.Arlo1 wrote:What If I rewind it? And get more copper fill? I want 80 KW!!!!!!
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.dangerzone wrote: I somehow doubt it could be pushed to a 80kW 10 second burst
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.Arlo1 wrote: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!