# Small EV Cart performance questions



## maxvtol (Nov 11, 2009)

You'd need a Torque vs. RPM chart for your motor to use my spreadsheet. 

Sounds like your using something similar to what is on my bike, I've got a 800 watt motor, maybe 265 lbs bike and rider, so you mike expect something similar to what the manufacturer's chart shows:
hub motor link (scroll down a little to see the chart)

A good ~20 seconds to get up to 20mph on a flat road. They have different motors for more torque or more speed, depending on what you want. The tire size will make a difference on speed and acceleration of course.

With the info you've given using readily available motors, I'd say ~16 to 20 seconds to a top speed of 20 to 25mph on a flat road would be in the ball park. If you've got super low drag and/or a special motor, we'll need more info.


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## Rational (Nov 26, 2011)

maxvtol said:


> maybe 265 lbs bike and rider
> A good ~20 seconds to get up to 20mph on a flat road.


Using F = mA I get an F of 12 lbs accelerating this mass. Knowing the wheel radius and the average speed of 10 mph I guess the hp delivered to the wheel can be figured.

This calc. neglects low speed wheel/road friction and air drag. These can be measured with a hardware store spring and some kind of towing method.

The motor link is interesting
Range 36 MPH	7-9
Range 20 MPH	18*

The formula seems to be 
range in miles = 1125(mph^[-1.38])
at least for this vehicle.


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