Hummina Shadeeba wrote:
Vanarian wrote:Hummina Shadeeba,
Is there room for adjustability in the design of your hub ?
How do you determine the power and max voltage your hub can take ? How do you determine Kv? Windings size, number, form, position ?
How much power and voltage do you think I could pump out of something as narrow as say 45mm of width for a diameter of 80mm? I aim for 12S max as it is standard among boards and already too much for many.
There is room for adjustability in that nothing has been confirmed and everything is still open to input.
From my own asking on here as to why many little motors are capable of taking less voltage I heared the obstacle isn't the enamel on the windings but the rpm ability of the little bearings. The two bearings chosen so far are bigger than a typical outrunner so... But with a 1:1 the rpms people hit I doubt would be an issue
Determining max power would be decided solely by temperature ability I'm pretty sure. The magnets currie temp (where they lose their magnetism) being the weakest link and id like to get high temp N42s at least. But with higher temp the magnets gauss or strength typically is less but high temp n42s is what i was going for. The enamels ability to handle volts doesn't seem to be a problem and from what I read it'll be the same for a 12s or 8s motor...and the bearings are the weakest link
I've been telling them I'm looking for 125kv as it seems a good balance between induction and amp ability as the amp ability goes down with the thinner winding but the induction coming from the multiple thin winds is needed with the 1:1
From what I've read the dLRK wind has the best power ability done with a 12 teeth x 14 magnet configuration that this would be.
I'm not sure what you're asking about form or position
I'm not sure what voltage these would be able to take and the manufacturers ask this as well as the rpm needed. What you think the obstacles are?
So far this will have a 30mm stator and be 63 mm diameter. That's as far as has been somewhat decided but if u have an extra two cents you could throw in please do as its all open to change and the more knowledge and opinions the better.
12s? I don't know. That's a lot of ssss's. I wonder how all those ssss's will multiply by the kv and what would be optimal but I think just getting the mechanical engineering right is most important now. That can be figured though and at this point I'll likey be getting 5 stator's to wind and I could wind them for different kv to see how they perform compared to each other as I bust out my infrared thermometer and graphing wattmeter which shows amps used and voltage!!!
What kv you think you'd want?!
I'd like to find people who are interested in getting these. If anyone would pay for just the materials I'd wind and put the magnets in myself. If enough people will do it then it'd be worth getting the 100 wheels made.
125Kv seems effectively a good balance since our wheels have limited size! For something as big as a bike wheel I'd have said otherwise but here Yes I agree.
I might not be wrong in thinking that when you talk about bearings, you talk about the 608 wheels bearings? Cr600 is the key if you really want killer bearings, and you will only find this in Cronitect which are overpriced for a "personnal" use... I'd recommend them only to guys going for serious racing with sponsorship.
You can simply get fast bearings like ILQ9 or Bones Swiss Red and flush them with synthetic oil and teflon. I talk of these two models because I found them to be solid and well built, while not being too expensive. I currently run ILQ9, pretty good bearings but ABEC 7 are stronger for shocks absorptions.
Bearings are not really your main concern, in fact unmotorized it is one of the last parts to care about when you talk about rotation speed. Of course it IS important, but in real conditions the wheel has always forces and external friction induced, thus killing the "near 0" benefit from a bearing. You should not worry too much about it, spinning a bearing as fast as a brushless motor will not kill it as long as it is quality bearing with good service and good oiling.
I want powerful hub motors to squeeze into 110mm inline sized and similar wheels, knowing that the inline standard is 22.5mm width. My request / idea is not sefish because this size also accomodates all the "offroad" and "pneumatics" sized
longboards wheels, so you're killing two birds with one stone. Having the motor to protude from the wheels is acceptable as long as it does not reduce the usable surface of the wheel. In longboard it is not an issue because wheels always stay perpendicular 90° to the ground, though in offroad ground itself will vary angle ; in inline skating too much protuding woumd definitely be an issue as to corner the rider needs to carve himself and lean on sides like a blade.
In fact this kind of hub motor is more profitable for an offroad board than a "carving" board because you have benefits on everythings :
-shocks? Motor is directly protected by the wheel around it. Lateral protectoin is easy, put an aluminium shield to keep it safe and light.
a street longboard is made to ride on flat surfaces, you usually don't risk much with a drive kit.
-Size. a 1:1 ratio for a low Kv motor like 125Kv will allow torquey accelerations, while a size like 110mm or more allow versatile top speed. Once one model is done you can always prepare others and determine the exact Kv and size of wheel ratio to always be in the motor's efficiency range, depending on how you plan to use it. Speed? Hills? COmmuting? Racing? Bashing? This is what I mean.
-Size again! It is easier to build a reliable hub motor with appropriated space, since we need lots of power, than fitting it into 80mm tiny wheels. Smaller wheels means lower surface to dissipate heat. More magnetic flux to fight with a so tight model if you aim for serious usable power. Give it more room and you'll be surprised to see how these problems will diminish.
Achieving a street longboard with 80mm wheels will built-in hub motors deserves big praises. As far as design and weight distribution go, it is the best in implementation. But pulley kits nowadays are so well developped and affordable, with the advantage to be able to easily swap pulley sizes, that it put shadows over the hub motors versions. So my vote goes for something more toward inline / offroad / pneumatic sized wheels.
What do you think of it?
I'm definitely in if we can work toward something similar to what I propose
Btw about max voltage, you need to determine the wire and iron ratio because V causes iron losses and A causes copper losses. We want to favorise iron losses but for that we need enough iron!