How does the cost per mile compare to a gasoline powered car?
This answer of course changes as the cost of gasoline goes up, but here’s my estimate. To start, you need to know that electrical energy is measure in Watt-hours, or Wh. One Wh means using 1 Watt of power for exactly 1 hour. So a 100-Watt bulb burning for 1 hour uses 100 Wh. The utility measures energy in increments of 1,000 Wh, or 1 kilo-watt hour, or 1 kWh. I’ll assume that the car uses 300 Wh per mile. This should be achievable goal if I drive with energy conservation in mind. The electrical utility that feeds my home (Xcel Energy) charges me almost exactly 10 cents per kWh. If I drive 30 miles a day at an average energy of 300 Wh per mile then I’ll use 9,000 Wh, or 9 kWh. The efficiency of the charger is less than 100%, and all of the energy that goes into the batteries doesn’t get stored as usable electricity to eventually move the car – some of it goes into heat. If I assume that the efficiency of the charger and the battery heat losses add up to 80% (a number I cannot yet verify
