True capacity of those 750watt and up hub motor?

[Sinewave]

whats the highest voltage anyone has given a hub motor?... is 75 mph obtainable with a hub motor without burning it up? im planning a 60v40ah or 72v30ah system .with the frame built from the ground up with motorcycle suspension.

if a hub can handle this, than that makes things alot easier...if not i'll either use an etek type motor or rewind the hub for higher current...any chance an rc motor can hit 75 mph ?

 

[pwbset]

I think Lazarus ran 112v on an X5. Doctorbass and methods run 100v+ around 45mph tops. I'm running 84v nominal on a measly little 4011 without issue so far. Even with a way over volted/amped 5302 I think you're going to have a really hard time getting to 75mph... if it's even possible.

 

[dogman dan]

Even an etek may be undersise for the speeds you are looking for. There is a bit more info specific to motorcycles and large scooters on the V is for volts forum. There are good reasons motorcycles that go 75mph are kinda large and heavy. Have you ever experienced high speed wobble on a bicycle going about 60 mph? Wow look how much that frame can bend! Once was enough for me!

 

[markcycle]

whats the highest voltage anyone has given a hub motor?... is 75 mph obtainable with a hub motor without burning it up? im planning a 60v40ah or 72v30ah system .with the frame built from the ground up with motorcycle suspension.

if a hub can handle this, than that makes things alot easier...if not i'll either use an etek type motor or rewind the hub for higher current...any chance an rc motor can hit 75 mph ?

My motorcycle with a 5302 hub motor at 48 volts and 100amps and a boost motor can hit 50 MPH, sustain 45 MPH. The bike weights 225. I concluded to do highway speeds requires a 300 to 350 pound bike if for no other reason as you need a bike that big and heavy to carry enough batteries to be practical. To me practical is at least 30 miles at 60 MPH. The wind resistance for a upright bike at 60 is huge probably needing 20 to 30 hp

Mark

 

[voicecoils]

Vetrix goes 62mph on a 21kW hubmotor.

The motor is integrated into the swingarm IIRC so it could not be easily modified to another bike.

See pages 19 and 20:
http://www.vectrix.com/shared/pdf/manuals/English-manual.pdf

 

[Sinewave]

seems like i may have to use a higher kv motor and possibly a dual motor setup to defeat low speed lag.

anyone know the kv for the etek type motors?

hmmm...so no one right now is using gearing to help get to 75mph ,well i suppose you cant with hub motors...well on second thought i bet you can, but would have to rework the motor...alot of rework.

 

[swbluto]

It is possible to go 75 mph with a hub but it wouldn't be "conventional" by any means. It'll require modification of some sort.

Having said that, you could go 75 mph with something more "normal"... but you'll have to reduce the aerodynamic requirements. That is, make the frontal area smaller and/or improve the coefficient of drag by making it more "aerodynamic"(like the aptera) and a higher KV motor, along with a high voltage, can make 75 mph. If you're looking for something "normal", you're probably going to have to customize something.

 

[Sinewave]

i edited my post and you replied with just about what i was going to say...lol

was trying to avoid making an aerodynamic fairing, but now it looks like it is going to be a requirement...i read somewhere that it takes 5 mph to push past the wind resistance at around 55mph...i think this was by ford, but not sure of the surface area or shape of the object being tested.

hi Mark, whats your battery setup rated at Ah wise?... not at maximum draw or limited.

i think theres a BIG leap in requirement for 55mph and 75 mph....maybe i will consider going AC.

 

[markcycle]

My battery is 48volts at 60 AH LIFEP04 batteries consist of three 48 volt 20ah packs in parallel. Made by HI POWER

http://www.chinahipower.com.cn/

Mark

 

[swbluto]

i think theres a BIG leap in requirement for 55mph and 75 mph....maybe i will consider going AC.

The power demand is going to be roughly cubic to velocity, so the power demand would be roughly (75/55)^3 or ~2.5-2.6 the amount of power required at 55 mph. So it's a definite jump, but not totally possible given the right motor and cooling. However, decreasing your drag coefficient by 3 times(not impossible - A normal bike has a drag coefficient of .9 while the aptera has a drag coefficient of .05-.1; Fairings would get you somewhere in between) will get you to that speed if you gear/"choose the right Kv" accordingly and you won't have a significant increase in the power(Actually, it should be less) consumed.

Hmmmm.... what's so great about AC motors? I keep hearing them as being used for the powerful setups for some reason, but I'm not sure why.

 

[Link]

Hmmmm.... what's so great about AC motors? I keep hearing them as being used for the powerful setups for some reason, but I'm not sure why.

Fairly efficient, a lot of them made for high-powered applications, don't really have a voltage constant, flattish torque curve, and they're cheap to make. Problem is that their controllers are very expensive. :?

 

[swbluto]

Hmmmm.... what's so great about AC motors? I keep hearing them as being used for the powerful setups for some reason, but I'm not sure why.

don't really have a voltage constant, flattish torque curve

Woah... that's... amazing. I must learn more.

 

[billvon]

Fairly efficient, a lot of them made for high-powered applications, don't really have a voltage constant, flattish torque curve, and they're cheap to make. Problem is that their controllers are very expensive. :?

Also nearly indestructible and fairly light. Light weight and efficiency are sort of competing objectives though.