Calculating Range

Calculating range is an exact science. And to do the calculations you need to be nothing short of a quantum physicist. The ranges that I have posted on my site are my best estimations. I came to them by combining a couple different tools and resources.

  1. 1. Check out Jerry’s calculator here:
  2. 2. Look at similar conversions here:

The calculator at EV Convert is very in depth and asks you everything from gear ratios to Puekerts values. There are a lot of presets that you can choose from to get an idea of what range and speed you are looking at. This calculator gave me an estimated range of 80 miles in perfect conditions, and about 40 miles at 40mph in realistic conditions (hills, wind, etc…).

The second site EV Album is basically an online EV car show. People from all over the country that have converted their cars post the cars stats online. Here you can see what components others have used and what results they have actually gotten. I found that most smaller cars (like mine) usually use about 300 watts per mile. I plan on putting a 16kWh battery pack in the car which would give me a range of about 53 miles.

The range of an EV depends mostly on battery pack and weight (although there are many other factors). I don’t have any special plans or tricks to increase range. I might buy some low rolling resistance tires. A spoiler of some sort will help reduce drag. During the conversion I’m going to remove every bit of extra weight from the vehicle that I can.

Deciding which motor to buy depends on several factors. What are your plans for the car? How fast do you need to go? What kind of acceleration do you need? How heavy is the car you are converting? How much money do you have? The general rule of thumb here is more volts=more performance. I used the calculators at EV Convert and plugged in a couple of different motors to get an idea of how they would perform. I also used the information on EV album to see how the different voltages performed in different vehicles. Just like in a gas car though, more speed and quicker acceleration means you will use more fuel (electricity).

When I started this project, I knew little to nothing about electricity. I am learning more and more as I go. Below is a little cheat sheet I hope can help in planning your project.

  • Volts – as far as the motor goes, I compare this to regular gas engine size. 6 cylinders will give you more performance than 4, just the same 144 volts will give you more performance than 72.
  • Amps – This is the current. A fuel gauge in a regular car measures how much fuel you have left in the tank, a “fuel gauge” in an EV would measure how many amps you have left in the batteries. Whenever you see amps, it is implied that they’re speaking of amps per hour (amp/hr). When talking about the amps in a battery, it is usually implied that it is at the 20 hour rate. For example, a 220amp battery will put out “X” amps over a period of 20 hours.
  • Watts – Watts = amps x volts. I will have 12x 6 volt batteries @ 220 amps a piece. I will connect the batteries in series therefore will have a pack voltage of 72. 72volts x 220amps = 15840 watts. Since a kW = 1000 watts, I will have a 15.84 kWh battery pack. This calculation is very useful when figuring out how much the car will cost you to charge.