Hello Readers,
This site was born today, May 18th, after I made payment on my first set of parts. It is dedicated to the construction of a road-legal electric car in my backyard. To build this car, I am starting with a golf cart motor, controller, solenoid, and M-COR, which I have just purchased. As time goes on, I will acquire a set of batteries, chargers, various electronic micro-components, and other various parts, as well as steel tubing, which I will weld into a frame. While all of this may seem unrealistic to you, I should make it clear that it seems the same way to me. However, I am determined, and I am proceeding as I would eat an elephant: one bite at a time.
As far as specifications, my motor is 48v and 3.2 horsepower, or 2.4 kW, for you metric folks. It is off a Club Car brand golf cart, and I believe it is shunt wound, meaning it prefers to run at a constant speed. This already seems like a problem, however the controller I am using, a Curtis 1266, should be able to fix this with some programmable settings.
As far as batteries, the motor runs at 2.4 kW at full draw. Current usage is equal to the watts divided by the volts, or 2400/48=50A. However, as the ever-helpful (http://www.diyelectriccar.com/forums/showthread.php/ev-information-669.html) tells us, we cannot take the batteries below 20% charge, else they will not charge back up, and since we are using the power quickly, we get less of it. The result is, we need about 115 A to run the motor. For those of you unfamiliar with electrics, A stands for amperes, a measure of current per time. So 115 A for 1 hour equals 115Ah, or Ampere-hours. How accurate this estimation is remains to be seen, however i will need around 115Ah per hour of use.
The other factor in power storage is voltage. Since my motor runs on 48v, I need 48v or batteries, or 4 12v's. In the 4 batteries, the voltage will add, but the current will not, since they will be in series rather than parallel. With these facts in mind, I have tentatively selected as my batteries 4 Kirkland 12v marine batteries, each with 115Ah. This will give me the 48v I need, with the power to run full power for around an hour. However, they cost $84 each, and weigh 55.5 lbs each. I am hoping to run into a better deal second hand, but only time will tell.
Regarding the non-electronic side of the car, I have fewer details figured out. The body will be some form of steel tubing, likely 1.25" EMT. It will be only big enough for one rider, and have three wheels, two in front and one in the rear. The reasoning behind the single rear wheel is the weight savings and simplicity of not having to split power between two drive wheels. The wheels themselves will likely be from BMX bikes, to keep cost and weight down. Lastly, I am undecided as to whether the car will have anything other than a direct drive system. While gears might be nice, I believe they may be unnecessary. The car should only be able to hit 45, and even that may be more than I will ever use.
While I could go on writing all day, I think this is a good time to stop. I hope this site will serve as an interesting and informative log of my progress for any friends, family, and strangers who may be reading. Any questions or comments, feel free to email me at webmaster@nathanielhill.com