This article explains how to calculate the costs of charging your Electric Vehicle and the Cost Per Mile. This article will be kept as simple as possible.
Cost of Charging Formula:
Price= Price of electricity from power utility. (usually about $0.09 U.S. per Kilowatt hour (KWh))
Energy = Amount of energy your battery charging system uses (in Kilowatt hours)
Price Per KWh = Total cost to charge batteries.
Cost Per Mile:
Cost = Total Cost of a full charge of your EV's batteries. (from the formula above)
Range = Total Range of your EV from a full charge, in Miles, Kilometers or any other distance measurement.
Explanation of Formulas:
First you need to understand that Electric Utility companies usually charge per Kilowatt Hour (KWh) for example $0.10 per KWh.
1 KWh is equal to 1000 Watts being used for 1 full hour (thus 1 Kilowatt used for an hour).
If you draw 100 Watts for 10 hours that totals 1 KWh.
If you draw 500 Watts for 2 hours, that totals 1 KWh.
If you draw 1000 Watts for 1 hour, that totals 1 KWh.
Even if you drew 4000 Watts for 15 minutes it's still a total of 1 KWh of electricity.
Cost Calculation Example:
Just some example numbers here to show how the formulas work, don't take this as what your EV will cost.
If your charger draws 2000 watts(2 Kilowatts) while charging and can finish charging your batteries in 8 hours that's 16,000 watt-hours or 16 KWH of electricity.
Lets say your energy costs $0.10 per KWH, then you just used $1.60 worth of power to charge your EV.
If your utility charges less money per KWH at night, then it could cost less.
Now, to get your dollar cost per mile you take the cost of a full recharge of your EV $1.60 and divide it by the amount of miles you can travel on that charge, lets say 50 miles, you get $0.032 per mile (3.2 cents per mile) as the cost of electricity to for driving your EV. This is generally much cheaper than a gasoline car - for example, a car getting 40 MPG with gasoline at $4 per gallon uses 10 cents worth of gasoline per mile.
You should also consider the cost per mile of batteries. Most current battery technologies will not last the life of the car so will be buying a set of replacement batteries. The cost per mile for batteries can easily exceed the cost of the electricity used.
If you want to calculate your equivalent MPG from that electric charge, that's much more complex
These are theoretical numbers, but they represent fairly common values and they are accurate. This is how to get the electrical costs for operating an EV.