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An Assessment of Level 1 and Level 2 Electric Vehicle Charging Efficiency

Investigating Potential Applications of Efficiency Measures to Various Electric Vehicles and Their Supply Equipment.

North American electric vehicle (EV) sales are projected to grow steadily in the next decade, becoming a significant portion of the vehicle fleet. Widespread electrification of personal transport will require coordination between the electricity and transportation sectors. This coordination could include application of electric efficiency incentives that are commonly used in the energy sector for more efficient products, such as energy star appliances. As with other technologies, the use of incentives for more efficient vehicles and charging equipment will facilitate a faster transition to this transformative technology. If EVs and/or electric vehicle supply equipment (EVSE) are found to be eligible for incentives, electric utilities can create programs which will accelerate EV deployment.

We compared the efficiency of 120V Level 1 to 240V Level 2 EVSE using FleetCarma logger data collected from 1,008 Chevrolet Volt charging events. We found that on average, Level 2 charging was 3% more efficient than Level 1, but this amount increased with shorter charge times. When less than 2kWh was drawn from the grid, Level 2 charging was 13% more efficient than Level 1. Although at all temperatures, Level 2 charging was more efficient, the differences in efficiency were greater at high (above 70° F) and low (less than 53° F) temperatures. The greatest efficiency gains for Level 2 charging are expected at public charging locations, where charge times tend to be shorter and weather conditions more variable, relative to residential sites. Providing incentives for efficient EV charging infrastructure through utility and government programs will ensure optimal long-term investment in this new technology, reduce energy use, and facilitate more rapid uptake of EVs. EV charging infrastructure is eligible for federal funding under MAP-21, thus transportation agencies could include efficiency benchmarks as a requirement for project financing.

This abstract appears with the permission of the Transportation Research Board. For the complete paper please visit http://pubsindex.trb.org

Justine Sears, Evan Forward, Eric Mallia, David Roberts, and Karen Glitman. 2014. An Assessment of Level 1 and Level 2 Electric Vehicle Charging Efficiency. Transportation Research Record (in press).

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An Assessment of Level 1 and Level 2 Electric Vehicle Charging Efficiency


  • Evan Forward - VEIC
  • David Roberts - VEIC
  • Karen Glitman - VEIC


  • Energy Planning
  • Program Review, Design & Implementation
  • Evaluation, Measurement & Verification
  • Transportation Efficiency
  • Emerging Technologies