# Need some help, building ev kart

Hi! I’m a high school student and i am planning to build an ev kart with KERS or RESS technology for my senior project. The chassis I have is about 160 lbs (rough estimate) and I weigh about 280 lbs and I am hoping of going some where between 20 to 40 mph. Anybody have suggestion on what kind of specs i should be looking for in a motor? Or even better accually know a motor I could use for this. Any help would be great.

I know that a 72v system can propel a 2,000 lb car at 55 mph. So I think a 36v system could propel a 500 lb cart at 40 mph easy. I don’t know in the way of a motor, but I’m sure you could find something on e-bay. If you give me some time I will calculate the HP you need.

I can calculate the Horsepower, Watt usage, and Amp draw, but first I need some more info. I need to calculate the aerodynamic drag, so I need to know how wide and how tall the cart is and its general shape.

But if I had to guess without the this information, then I’d say you need a 9 HP motor. Which means that you will be using 6,700 Watts. From here you are going to want to use the highest voltage you can. Because the higher the voltage the less amps you use. Here are some Voltage and Amp options (interval in 12v, because if your trying to work cheaply, then 12v lead acid batteries work fine)

12v = 560 amps (not a good option)
24v = 280 amps (better but not great)
36v = 190 amps (this would work)
48v = 140 amps (good if you could fit 4 batteries into that cart)
60v = 115 amps (I haven’t found a 60v motor controller though)
72v = 95 amps (This is about the max you can go cheaply)

anything above 72v is really expensive
Remember that this is a guess, I can make a better guess with a little more info.

Hope this helps

Yeah, this is great thank you, i still don’t accually have the chassis we are waiting for the guy who does have it to bring it in, the weight was a rough estimate he gave me so i will probably go with a 48 volt.

Glad I could help. You might want to use 1 ott (don’t know if I spelled that right) cables. If you use less that, then I think you should keep an eye on them. To make sure that they don’t over heat.

Best of luck