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How to Calulate the Cost to Charge an Electric Car
Let’s Figure-Out How Much to Fill the “Tank”
It’s easier than you think, let’s understand the difference from putting gasoline in your car.
When calculating the cost to charge an electric car, we assume everyone knows electricity is our fuel, rather than gasoline, diesel or propane. These traditional fuels use units of measurement in liters or gallons specifically for liquid volume. But how do we measure electricity?
Units of Measurement
We no longer use liters or gallons as the unit of volume for our fuel. Introducing the kilowatt (kW).
Power is measured in watts (W). Watts would be the equivalent of the rate of flow, coming out of a hose. In our world, we use lots of watts, so much, there is a unit of 1000 watts to measure electricity. 1000 watts for short, is a kilowatt (kW).
Different than liquids such as gasoline, diesel, or water, we need to measure how much will “fill” or charge our electric vehicle batteries. The principle is the same, we use volume, but the difference is that electricity is measured by how much it flows using time. Think of how fluid flows out of a hose to fill a tank, bucket or glass, but we use time. In this case, the “tank” is a battery and how much fluid ends up in the tank, is watt-hours (Wh), not liters or gallons.
This is also how much energy a battery can provide for a certain amount of time, in this case, hours.
The size of batteries, or should we say, the “capacity” of our tank, is no longer measured by how many liters or gallons, but rather how many watt-hours it can hold. Car batteries have a lot of capacity, so they are measured in kilowatt-hours (kWh).
Electrical companies (utilities) charge consumers by the kilowatt-hour.
The Formula
Ok, so let’s get down to it and figure out, the million-dollar question, how much does it cost to charge an electric car. Below we use residential or “home” electricity rates.
We need to find two things: the battery size in kilowatts of your electric car and the rate your utility charges per kilowatt-hour. They are the same unit of measurement (usually), so this is easy!
Let’s put it together!
You multiply battery size in kilowatt-hours by the rate charged by your utility, which is usually also in kilowatt-hours.
Battery size (kWh) x Utility rate for electricity in kilowatt-hours ($) = How much a “fill” will cost ($)
Let’s try it.
You have a 2021 Chevy Bolt with a battery size of 66kWh. You live in Manitoba, so the residential rate is super cheap at $0.09 per kWh.
66 kWh x $0.09 per kWh = $5.94 per “tank,” from 0 to 100%
Ok, maybe you have a new 2023 Ford F-150 Lighening, and the Standard Range battery pack with 98 kWh. Again, you live in Manitoba, so $0.09/kWh.
98 kWh x $0.09 = $8.82 per fill.
Ok, maybe you opted for the Lightning with a 131 kWh Extended Range battery pack, good for about 480 km or 300 miles on a nice warm day.
131 kWh x $0.09 = $11.79 per fill, or about 480 kms (again, on a nice day, not winter on the prairies).
How much to “top-up?”
Just find how much percentage your car is displaying on your dash, and subtract it from 100%. This amount will give you the remaining battery capacity. Once you have the percentage of the remaining amount, multiply that by the maximum battery capacity of your electric car. Let’s do it…
So, you still live in Manitoba, with its low residential electricity rate ($0.09 per kWh) and own a Chevy bolt with the 66 kWh battery, but you have 25% left in the “tank.”
100% – 25% = 75% of “tank” to fill. Let’s move it out of percentage and in to decimal form, so 75/100 = .75.
And calculate how much in kilowatt-hours you have remaining.
.75 x 66 kWh = 49.5 kWh of battery capacity remaining, or room in the “tank.”
Place the remaining battery capacity in to the formula and find out how much it will cost you.
49.5 kWh x $0.09 = $4.46 to “top-up the tank”
And there you have it!
Cost to Charge an Electric car in Ideal Conditions
We need to say, this is a best-case scenario calculation. It is not taking in to effect environmental conditions which may improve or degrade costs.
Your overall calculation for a year will depending on driving conditions and climate. You can expect to charge quite a bit more in cold Canadian winters and have days with out charging in the hot summer. It is a balance, but one that saves you a significant amount of money on transportation fuel in the long and short-run.
When people ask, how much of an increase will they expect to see on their home electricity bill, this depends. The size of your battery and frequency of use, much like gasoline, will impact your over all cost. We like to say, expect $20 to $50 more a month. This will give you an idea to what budget for. Using free sources can help, but more frequent third-party charging will cost you a bit more.
How much does it cost to charge an electric car at a public charger?
Very good question. It varies depending on company or site-host on the rate. In Canada, companies cannot charge by the kilowatt and resell electricity, yet.
What you will find, is that they will charge you for the time on the charger or for the parking at the stall. You will see rates vary from $2.00 per hour for a level 2 and $10.00 per hour or more for a level 3 DC fast charger. Level 3 chargers are significantly faster, and the idea to get you moving right away. These prices will change based on host, but you do pay more for convenience away from home.
The majority of electric vehicle charging is done at home, with lower rates, more time and convenience. Public chargers are mainly used on road trips, like gas stations or in times of need.