Fact #884: August 3, 2015 All-electric Vehicle: Where Does the Energy Go?

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Unlike conventionally fueled vehicles, electric vehicles experience a loss of energy during “refueling,” with an energy loss of about 16% from the wall power to the battery during charging. However, electric vehicles are otherwise highly efficient delivering about 65% of the energy from the wall power to the road even before energy is reclaimed through regenerative braking. When energy gains from regenerative braking are included, the amount of energy used for traveling down the road can rise to more than 80% in the EPA-combined city and highway driving cycle.

Energy Losses and Gains for an All-electric Vehicle for Combined City and Highway Driving

Energy losses and gains for an all-electric vehicle for combined city and highway driving. parasitic losses: 2.5%. electric drive system losses: 16%, power to wheels: 65% + 17% (recovered) = 82%, idle losses: near 0, net regenerative braking energy returned to the battery and subsequently to the road: 17%, energy lost in charging battery: 16%

Notes:
Total energy expenditures don't add to exactly 100% due to rounding. Results shown are for a 2012 Nissan Leaf operating in a temperature of 72 degrees Fahrenheit.
Energy lost in charging battery includes power conversion and internal battery charging losses.

Energy Losses and Gains for an All-electric Vehicle for Combined, City and Highway Driving

Bar graph showing energy losses and gains for an all-electric vehicle for combined city and highway driving.

Note: The figure is primarily showing losses, but the regenerative braking gains are shown below 0%, offsetting some of the above losses.

Fact #884 Dataset

Supporting Information

Energy Losses and Gains for an All-electric Vehicle for City, Highway, and Combined Driving
  Types of Driving
Combined City Highway
Types of Losses Energy Losses
Energy Lost in Charging Battery 16% 16% 16%
Electric Drive System Losses 16% 18% 14%
Parasitic Losses 3% 4% 2%
Power to Wheels, dissipated as:      
      Wind Resistance 36% 29% 45%
      Rolling Resistance 23% 25% 22%
      Braking 23% 40% 7%
Types of Gains Energy Gains
Regenerative Braking -17% -32% -6%

Source: Argonne National Laboratory data, SAE 2013-01-1462, and presentation.

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