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



## major (Apr 4, 2008)

EV Information


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## fahadn (Nov 26, 2014)

major said:


> EV Information


I've read all that stuff, on the link, which u shared... 
But I'm still unable to calculate the parameters I want.. 
Please help


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## Tesseract (Sep 27, 2008)

fahadn said:


> 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.
> ...
> how to calculate force needed by my car?
> how to calculate torque needed by my car?
> ...


Please don't post your homework questions here for us to do your work for you.


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## fahadn (Nov 26, 2014)

Tesseract said:


> Please don't post your homework questions here for us to do your work for you.


Sir, im not doing it for my assignment..
i want to make it in my garage.
ad i dont want to buy any motor which is not suitable to my needs.
thats y im looking for mathematical calculation, so that i will buy exactly wat my ride needs.

ive limited amount of money and dont want to waste it on wrong things


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## major (Apr 4, 2008)

fahadn said:


> I've read all that stuff, on the link, which u shared...
> But I'm still unable to calculate the parameters I want..
> Please help


Which part in particular stumps you? And please go to use CP and fill in your location so we have an idea of where you're from and native language and stuff like that. Thank you.

Also, you could educate yourself by reading. This book helped me years ago and I see it is available on line for free. 

http://ev-bg.com/wordpress1/wp-content/uploads/2011/08/build_your_own_electric_vehicle.pdf


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## gunnarhs (Apr 24, 2012)

fahadn said:


> 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.THANK YOU
> following is the basic known parameters:
> 
> Total mass of car(including rider and everything) = 250kg
> ...


 Hi, I copied once this part from the book which I bought, I very recommend it to you it is especially for non-engineers and also very good for practical implementation for advanced car converters)
(Build your own electric vehicle, Seth Leitman /Bob Brant)

http://www.hreinorkubilar.is/doc/BuildOurOwnElVehicle_Ch5.pdf

Best regards, Gunnar


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## gunnarhs (Apr 24, 2012)

He,he it seems major has posted the same complete book


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## GerhardRP (Nov 17, 2009)

fahadn said:


> <snip>
> Total mass of car(including rider and everything) = 250kg
> initial velocity of car = 0 (still car stop)
> max velocity = 60 km per hour
> ...


We can start from the beginning here: certainly you have heard the formula
F=ma everything has to be in meters, kilograms and seconds. Force will be in Newtons. You have given us the mass, the speed you want to reach and the time to reach that speed. Use meters/second rather than km/hr. [assume constant acceleration] So, plug in the numbers and report back your calculated force.
Gerhard
P.S. I would be scared to death, emphasis on DEATH, to go 60 KPH in that cart.


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## PStechPaul (May 1, 2012)

I used my http://enginuitysystems.com/EVCalculator.htm and plugged in your numbers. I assumed a frontal area of 0.5 m^2 and velocity of 60 k/h at acceleration of 0.3 m/s/s which is equivalent to a 3% slope.

Inertia (kinetic energy): 34,700 J (9.6 Wh)
Thrust: 145 Newtons (32.6 pounds force)
Power: 2.4 kW (3.2 HP)
Wheel RPM: 796
Wheel torque: 29 N-m (21.4 lb-ft)
Energy consumption: 40.3 W-h/km (65 W-h/mile)

These are just what is actually needed and does not take into account any efficiency or losses in the electrical or mechanical components. I agree that it may be worth your life to reach 60 km/h in that cart and you should have someone take video to show posthumously to your survivors as a lesson in Darwinian selection.


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