Username1 said:I know that KV is the unloaded rpm/volt. But what about when you are riding? Does kv accurately represent your top speed when when taking the wheel size into account? (dd hub motor) Or is the top speed actually less than the kv would suggest?
Drunkskunk said:What do you plan to use for a controller? With such a low voltage system, you are going to need to pull massive amps.
Username1 said:Thanks for the replies. So if my desired top speed is 20% below my kv, that should basically guarantee i can actually reach the top speed, and operate near peak efficiency?
Username1 said:So is there any efficiency penalty for selecting a kv that's way higher than you need? For example if your top speed was only 50% of the kv, limited using either the controller or just manual throttle control.
Username1 said:So is there any efficiency penalty for selecting a kv that's way higher than you need? For example if your top speed was only 50% of the kv, limited using either the controller or just manual throttle control.
Username1 said:So is there any efficiency penalty for selecting a kv that's way higher than you need? For example if your top speed was only 50% of the kv, limited using either the controller or just manual throttle control.
John in CR said:I do emphatically advocate building for a top speed greater than you use for safer riding in traffic...quicker passes and easier to create safe riding spacing well away from vehicles. In addition, I can't imagine using any vehicle used at WOT throttle since even the slightest hill or puff of headwind will slow you down.
Balmorhea said:For any given battery and controller, you get more initial and maximum torque from a slower wind motor, so there’s that too. You can have more capable climbing and better acceleration from a stop, without having to spend more or carry more weight.
John in CR said:Balmorhea said:For any given battery and controller, you get more initial and maximum torque from a slower wind motor, so there’s that too. You can have more capable climbing and better acceleration from a stop, without having to spend more or carry more weight.
That kind of restriction is like putting a gas tank and carburetor from a lawnmower engine on V8.
Balmorhea said:John in CR said:Balmorhea said:For any given battery and controller, you get more initial and maximum torque from a slower wind motor, so there’s that too. You can have more capable climbing and better acceleration from a stop, without having to spend more or carry more weight.
That kind of restriction is like putting a gas tank and carburetor from a lawnmower engine on V8.
If you do that, the engine will have less power, less torque, and less range. If you substitute a slow winding for a fast winding in a given system, it will have the same power, more torque, and more range. So I think it isn’t a good comparison.
fourbanger said:So, um, preference aside, am I to understand it that the best motor of choice for a given form factor will ALWAYS be the one that achieves top efficiency at the highest RPM withstanding pole count, lamination width etc?
I've always found it curios that so many sellers advertise their highest rpm models as low volt/low amp versions.
Eg. 36v 350w usually spins faster than the 48v 500w model.
Thoughs?