Fact #750: October 22, 2012
Electric Vehicle Energy Requirements for Combined City/Highway Driving
The efficiencies of electric vehicles can vary significantly; however, compared with conventional vehicles, they are very efficient—converting about 60% of the energy from the grid to power at the wheels. There are energy losses of about 16–19% from charging and battery storage while electric drive system and parasitic losses combined account for another 25–28%. Off-setting some of these losses, regenerative braking on electric vehicles produces an energy gain of 5–13% resulting in an overall efficiency of about 57–64%. By comparison, a conventional vehicle converts roughly 14–26% of the energy from fuel to power the wheels in the same combined driving cycle.
|Grid Power to Wheels||57-64%|
|Electric Drive System Loss||21-24%|
|Grid to Battery Storage Loss||16-19%|
|Regenerative Braking Gain||5-13%|
|Sources: Estimated by Oak Ridge National Laboratory using published sources including: Fuel Economy Guide Website, "Electric Vehicles."Fuel Economy Guide Website, "Fuel Economy: Where the Energy Goes." Miller, et.al., SAE 2011-01-0887. Chae et. al., 2011. Gautam et. al., 2011.|