# motor calculation & wheels connection

Discussion in 'General Electronics Chat' started by Robert123, Feb 24, 2010.

1. ### Robert123 Thread Starter New Member

Feb 12, 2010
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I want to build a simple carting car that will can to arrive 35 km/h
My problem now is what motor I need to buy ?
How I calculate the motor data that I need ?
I search after good site or name of book that explain how to calculate the appropriate motor
I think a bout the motors that are in the electrical scooter maybe anybody here know the number of the motor and then I can search his data sheet
Also I want to know how to connect two wheels that I will can to control the direction of the drive

2. ### retched AAC Fanatic!

Dec 5, 2009
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Jul 7, 2009
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To pick a motor, you'll need to know the mass of the car, efficiencies, frictional losses, the acceleration you desire, wind resistance, and probably a number of other things. The best approach would probably be to go to a library and find a book on electric vehicle design. I would imagine to do an accurate design on paper is not a trivial task. Most people would probably find some guidelines and overdesign a bit.

Since the motor is likely to be a DC motor, you can "simply" reverse the leads to make the motor run backwards. But this also isn't trivial, as it will probably be a fairly high current load and you need to switch it properly (i.e., not under load), so there is additional logic required. The book on electric vehicle design will also likely have relevant information on this task (plus other niceties I'm unaware of).

4. ### retched AAC Fanatic!

Dec 5, 2009
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You will want to look up the relationship of horsepower between electric and internal combustion motor/engine. If you are just replacing the engine with a motor, keeping the transmission, you need not worry about the reversing. All the other math has been done for you regarding transmission. So, you can find a electric motor that has a basic correlation with the original gas engine, and swap. just as was done in the site I previously linked to.

If the gas motor red lined at 6600rpm. You are going to want a electric motor + gearbox that will achieve around the same give or take a few hundred rpm, because thats what the trans is rated for. You also want the torque to match about the same. Because the manufacturing of the drive-train may not be able to handle a extremely high torque electric motor. You will start stripping out gears, and the such.