Standard size electric motors?

[Tpdingo]

Ok, so far ive seen your standard 36/48V 350s, 500, 800, 1000, 1500, 1800W and then on the higher end 60V 2000W and 72V 3000W. Are there any cheap eBay motors that are bigger/more powerful than 3000W?

Also slightly OT but, how do wattages compare to gas horsepower in terms of acceleration and top speed. Like a reasonable conversion formula.

 

[garolittle]

Also slightly OT but, how do wattages compare to gas horsepower in terms of acceleration and top speed. Like a reasonable conversion formula.

Others can correct me if I’m wrong but I believe that approximately 750 Watts equates to 1 hp. Therefore 7500 W would equal 10 hp.

 

[itsid]

745W

engine power is also properly designated in (kilo)Watts at all times (just look in your manual)

But you still cannot comapre the two really
an electric motor works almost the other way around as a combustion engine.

an engine needs rpm (lots thereof) to produce torque (peak torque is at around 2500 rpms)
an electric motor does not.. in fact it's peak torque is close to stalling speeds (~1 rpm)
And worse: electric motor torque is NOT as closely related to the motor power as it is in combustion engines.

And since torque is what moves you forward, horsepower is no indicator at all

It's quite common that a 2kW motor is closer to a 4kW engine than a 2kW engine...
but you can't take that for granted either I'm afraid

depends on the motor and the proper gearing of course

A slow turning high amp motor makes more torque than a low amp speeder
just like a slow turning high combustion volume four stroke makes more torque
than a same nominal power lower combustion volume two stroke engine.

So two different identically powered motors have very different torques at different speeds
(or say CAN have)


What you really want to compare is wheel torque...
(torque after all gear reduction)
and that is a matter of set up only.
You can set up both to outaccelerate the other or to match,
it largely doesn't matter what power you pick
And the other way around you could also outspeed one with the other (within reason)

We've seen a 1kW motor propelling a kart with a kid to close to 50mph
something you'd have a really hard time trying with a 5kW enigne..
and we also seen 2kW motors accelerating WAY quicker than you'd be able to with a 5kW engine...
unfortunately you cannot do both usually..

Short:
there is no way of 'mathematically' comparing the two
since they work very differently and have their strengths and weaknesses at very different times.

'sid

 

[Functional Artist]

Ok, so far ive seen your standard 36/48V 350s, 500, 800, 1000, 1500, 1800W and then on the higher end 60V 2000W and 72V 3000W. Are there any cheap eBay motors that are bigger/more powerful than 3000W?

Also slightly OT but, how do wattages compare to gas horsepower in terms of acceleration and top speed. Like a reasonable conversion formula.

Ya start drifting away from "cheap/low cost" really fast when you start talkin' about "more powerful than 3,000W"

Most of the Mars type motors (brushed & brushless) are ~$500.00+
...then, lower cost Kelly controllers are ~$300.00 & up
...the higher end Alltrax, Sevcon's & such are usually ~$500.00 & up

or

Check out Golden Motors as a different example:
https://www.goldenmotor.com/frame-bldcmotor.htm

5KW brushless motor (~$450 fan cooled or ~$500 liquid cooled)
Model: HPM5000B -- High Power BLDC Motor
Voltage:48V/72V/96V/120V
Rated Power:3KW-7.5KW
Efficeincy: 91%
Phase Resistance (Milliohm): 6.2/48V; 12.0/72V; 36.0/120V
Phase Induction(100KHZ): 68uH/48V; 154uH/72V; 504uH/120v Speed: 2000-6000rpm (customizable)
Weight:11Kg(air),11.35kg(water); Casing: Aluminium
Length (height): 126mm Diameter: 206mm
Keyway size: 5mm(W) x 43mm(L) x 19mm(D:22.3mm)
Features: Compact design,Water resistent, Stainless Steel Shaft, Self Cooling Fan
Applications: Electric car, electric motorcycle, electric tricycle, electric golf carts, fork lift, electric boat, etc.

(plus the matching speed controller)

5KW BLDC Motor Controller (~$450.00)
Model: VEC300
Voltage:48V/72V/96V
Rated DC BUS current:30A-200A
Rated output power:1000-10000W
Motor control mode:FOC
Quiescent operation
current:20~40mA
Speed limit:Controlled by motor and configuration
Driving methodirect torque control
Keyway size: 190mm(L) x 180mm(W) x 50mm(H)
Weight:2.5kg)

NOT to be a downer
...but, ya for 5Kw+ your talkin' close to $1,000.00 even before contactor, fuses, cables or batteries.

* I know, its hard to equate that with ~$100.00 for a 6.5HP Predator
...but, I've rode both (gas & electric karts) there IS a HUGE difference

 

[Tpdingo]

Ya start drifting away from "cheap/low cost" really fast when you start talkin' about "more powerful than 3,000W"

Most of the Mars type motors (brushed & brushless) are ~$500.00+
...then, lower cost Kelly controllers are ~$300.00 & up
...the higher end Alltrax, Sevcon's & such are usually ~$500.00 & up

or

Check out Golden Motors as a different example:
https://www.goldenmotor.com/frame-bldcmotor.htm

5KW brushless motor (~$450 fan cooled or ~$500 liquid cooled)
Model: HPM5000B -- High Power BLDC Motor
Voltage:48V/72V/96V/120V
Rated Power:3KW-7.5KW
Efficeincy: 91%
Phase Resistance (Milliohm): 6.2/48V; 12.0/72V; 36.0/120V
Phase Induction(100KHZ): 68uH/48V; 154uH/72V; 504uH/120v Speed: 2000-6000rpm (customizable)
Weight:11Kg(air),11.35kg(water); Casing: Aluminium
Length (height): 126mm Diameter: 206mm
Keyway size: 5mm(W) x 43mm(L) x 19mm(D:22.3mm)
Features: Compact design,Water resistent, Stainless Steel Shaft, Self Cooling Fan
Applications: Electric car, electric motorcycle, electric tricycle, electric golf carts, fork lift, electric boat, etc.

(plus the matching speed controller)

5KW BLDC Motor Controller (~$450.00)
Model: VEC300
Voltage:48V/72V/96V
Rated DC BUS current:30A-200A
Rated output power:1000-10000W
Motor control mode:FOC
Quiescent operation
current:20~40mA
Speed limit:Controlled by motor and configuration
Driving methodirect torque control
Keyway size: 190mm(L) x 180mm(W) x 50mm(H)
Weight:2.5kg)

NOT to be a downer
...but, ya for 5Kw+ your talkin' close to $1,000.00 even before contactor, fuses, cables or batteries.

* I know, its hard to equate that with ~$100.00 for a 6.5HP Predator
...but, I've rode both (gas & electric karts) there IS a HUGE difference

Well thanks FA and itsid,

I'm mostly on the acceleration side, feeling like a Tesla without going as fast as one.
I saw some electric scooter that could do a speedy 40mph on 3600W, plus that's with an extremely unaerodynamic design(aka standing person). I figure if that's the case, 3000W(4ish HP) would be plenty for good for much more than I could even reasonably expect out of a 8HP Predator.

 

[Quinc]

Pick up an industrial motor for 100$ on ebay. 1hp Leeson or clarke will give you what you need. If not get an imperial 3.6hp forklift motor.

http://www.diygokarts.com/vb/showthread.php?t=39038