How much does it cost to charge a cell phone or Tesla vehicle?

Have you ever wondered how much money does it cost to charge a cell phone or perhaps a Tesla vehicle? The first step to answer this question is to know how much you pay for electricity. This website from the Nebraska Goverment gives us an idea of the average cost of electricity per state, in cents per KiloWatt-hour. The next step is to find out the capacity of the battery for the device of interest.

The battery capacity for an Iphone 6 is about 6.9 Watt-hour, and about 9.8 Watt-hour for a Samsung Galaxy S6. For these calculations we will need to make a couple of assumptions and approximations. I decided to include a 95% efficiency in the charging process and also decided that my device will be charged 1.5 times per day, 365 days per year. It turns out that it costs about 50 cents per year to charge a cell phone. Overall, I was surprised how relatively inexpensive it is to charge a cell phone given everything that a cell phone does for us these days.

The battery capacity of a Tesla vehicle ranges from 70 KiloWatt-hour to 90 KiloWatt-hour (about 10,000x larger than your phone). The average range of a Model S is about 240 miles, battery-only. On average, a vehicle is driven 12,000 miles per year, which would be equivalent to charging your Tesla 0.137 times per day (about once every 7 days). Using a 95% charging efficiency and 365 days per year, it costs about $440 per year to charge a Tesla Model S. I do not own a Tesla yet, but I will do some approximations to relate this number to the cost of driving a gasoline vehicle. An average of 12K miles per year is equivalent to 27.3 miles/$ for Tesla. My current 4 cylinder 2.0L car gets about 30 MPG. Currently, gas is about $2.5/gallon (May 2016). Therefore, my 4 cylinder 2.0L car costs 12 miles/$ or 2.3x the price of Tesla for the same distance.

For reference, here are the numbers for the cost to charge per year:





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