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Calculate DC motor specifications (torque power etc) for electric vehicle? Answered

Dear Sir/Madam,

I want to make an electric car like as shown in figure below., with a DC motor. assume no inclination, road is plain surface. please explain all calculation with formulas. Thanking in anticipation
following is the basic known parameters:

Total mass of car(including rider and everything) = 170kg
initial velocity of car = 0 (still car stop)
max velocity = 30 km per hour
time to reach max velocity = 1 minute = 60 seconds
radius of tyre = 8 inch

please tell me how could i find the following parameters to find accurate DC motor for my car:

how to calculate force needed by my car?
how to calculate torque needed by my car?
how to calculate speed RPM of a motor needed by my car?
how to calculate power (watt) of motor needed by my car?



2 years ago

This is why I hate answering homework questions, never any thanks or appreciation! Feeling unwanted this morning :-(


Answer 2 years ago

I do not think he understands what he is asking let alone a technically correct answer.

I bet he copies your text numbers for numbers..


Answer 2 years ago

More than likely, and his tutors won't care either. The confusion of knowledge vs understanding seems to be ever widespread.


2 years ago

Why do I get the feeling that this is another school / university project?
Sorry but sounds far too much like questions a teacher would ask the students to find out....


Answer 2 years ago


However No picture attached so we don't know what sort of vehicle your going to make.

A number of simple basic points:

It will have to be as light as possible. You will have to build VERY light to attain 170 kg with driver.

Without knowing the drag factor you can't do better than guess at the other figures.


our motor was run at 500 watts 2000 RPM at the motor shaft. gear ratio 14:1 with much the same size wheel.

500 watts is 20 amps at 24 volts. The gave us the capability of traveling about 60 miles on a single charge. weight about 170 kg.

Max speed about 28 MPH although at many times it would be faster or slower than that depending on the gradient.