All-electric vehicles (EVs) run on electricity only. They are propelled by one or more electric motors powered by rechargeable battery packs. EVs have several advantages over conventional vehicles:
- Energy efficient. EVs convert over 77% of the electrical energy from the grid to power at the wheels. Conventional gasoline vehicles only convert about 12%–30% of the energy stored in gasoline to power at the wheels.
- Environmentally friendly. EVs emit no tailpipe pollutants, although the power plant producing the electricity may emit them. Electricity from nuclear-, hydro-, solar-, or wind-powered plants causes no air pollutants.
- Performance benefits. Electric motors provide quiet, smooth operation and stronger acceleration and require less maintenance than internal combustion engines (ICEs).
- Reduced energy dependence. Electricity is a domestic energy source.
EVs have some drawbacks compared to gasoline vehicles:
- Driving range. EVs have a shorter driving range than most conventional vehicles—although EV driving ranges are improving. Most EVs can travel more than 100 miles on a charge, and some can travel in excess of 200 or 300 miles depending on the model.
- Recharge time. Fully recharging the battery pack can take 3 to 12 hours. Even a "fast charge" to 80% capacity can take 30 min.
Batteries for EVs are designed for extended life, and a study by DOE's National Renewable Energy Laboratory suggest these batteries may last 12 to 15 years in moderate climates and 8 to 12 years in severe climates. However, these batteries are expensive, and replacing them may be costly if they fail.
EV energy use estimated by ORNL as follows:
- Electric motor efficiency—including inverter and gear reduction losses—assumed to be 76.4%–80.2%, using estimates from Miller et. al. (SAE 2011-01-0887) and adjusting downward by 4% for parasitic losses.
- Battery charging efficiency can vary, but it is often 84% to 93%, based on published studies
(Chae et. al., 2011;
Gautam et. al., 2011)
and data from the Idaho National Laboratory Advanced Vehicles website:
- Charging System Testing - Vehicle Charging System Testing (see Steady State Charging Power Quality and Efficiency)
- Charging System Testing - EVSE Testing – All