How Much Does It Cost To Charge An EV With A Plug From Your House?

I’m a nerd, and I love data. I also do home energy efficiency for a living, so when I got my Tesla last year, my housemates asked me what kind of impact it would have on our electric bill, and I wanted to be able to provide some data to them — 1) to showcase how cool EVs are, but more importantly, 2) so that they wouldn’t make me pay 80% of the bill.

So I decided to do a little experiment and document it. Here’s what I did:

Plug in a watt meter, and measure the car’s electricity consumption from the wall outlet. In this case, I used a Kill-A-Watt meter. I plugged the watt meter into the wall, then my Tesla level 1 charging cable into the watt meter, then the other end of the cable into the car. I got a steady reading after a little oscillation period, of 1384 watts, or 1.384 kilowatts.
Next, I let it charge for a couple of hours (2.5), and then measured how many miles it added to the vehicle. Turned out it was 14.
Once I unplugged the car, I did the math, which you can see in the video below.

In 2.5 hours, 14 miles were added. That means roughly 5.6 miles per hour of charging on the level 1 at my house. My Tesla says 6, so it’s pretty accurate.

The first data point I attempted to solve for here is miles per gallon equivalent on the Tesla. At the charging level (not the driving level, which may be fodder for another video soon), it comes out to 136 miles per gallon equivalent. As I mention in the video, that’s just one data point, but a pretty cool one.

The next is how much it costs. My battery is set to 220 miles for a full charge, so I applied the math and ended up with a pretty terrific figure for the cost of filling up the “tank.” First, I’d love to hear guesses in the comments below. Then, after you comment, check out the vid to learn more!

Assumptions:

11¢ per kilowatt-hour (our national electricity average cost here in the US)
33.7 kWh is roughly equal to a gallon of gas (according to the EPA)

Enjoy!

Original Publication by Scott Cooney at CleanTechnica.

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