Evaluation of Fast Charging Efficiency under Extreme Temperatures

Abstract

Multi-type fast charging stations are being deployed over Europe as electric vehicle adoption becomes more popular. The growth of an electrical charging infrastructure in different countries poses different challenges related to its installation. One of these challenges is related to weather conditions that are extremely heterogeneous due to different latitudes, in which fast charging stations are located and whose impact on the charging performance is often neglected or unknown. The present study focused on the evaluation of the electric vehicle (EV) charging process with fast charging devices (up to 50 kW) at ambient (25 • C) and at extreme temperatures (−25 • C, −15 • C, +40 • C). A sample of seven fast chargers and two electric vehicles (CCS (combined charging system) and CHAdeMO (CHArge de Move)) available on the commercial market was considered in the study. Three phase voltages and currents at the wall socket, where the charger was connected, as well as voltage and current at the plug connection between the charger and vehicle have been recorded. According to SAE (Society of Automotive Engineers) J2894/1, the power conversion efficiency during the charging process has been calculated as the ratio between the instantaneous DC power delivered to the vehicle and the instantaneous AC power supplied from the grid in order to test the performance of the charger. The inverse of the efficiency of the charging process, i.e., a kind of energy return ratio (ERR), has been calculated as the ratio between the AC energy supplied by the grid to the electric vehicle supply equipment (EVSE) and the energy delivered to the vehicle's battery. The evaluation has shown a varied scenario, confirming the efficiency values declared by the manufacturers at ambient temperature and reporting lower energy efficiencies at extreme temperatures, due to lower requested and, thus, delivered power levels. The lowest and highest power conversion efficiencies of 39% and 93% were observed at −25 • C and ambient temperature (+25 • C), respectively.

Battery Electric Vehicle Fast Charging–Evidence from the Norwegian Market

“…A 22-36% decrease in the fast charge power at 0°C vs 25 °C has been found for Taxis in New York City [18], and the effect will be even larger at temperatures below 0°C [21]. Trentadu et al [21] found that the fast charge power for a specific BEV model was reduced to 4.1-4.8 kW at −25 °C and 4.3-17.6 kW at −15 °C, for different fast chargers tested in a laboratory environment when starting from 25% vehicle SOC. Above 25 °C the charge power was stable at the maximum achieved value of 38 and 47 kW depending on the charger they tested.…”

“…The research on fast chargers have mainly focused on the technical design of the vehicle and the integration with and interface to the electricity network [8,9], the needs of users [6,[10][11][12], the optimum positioning and number of chargers needed to support the flow of vehicle [6,10,[13][14][15], cold/warm weather effects [16][17][18][19][20][21], and the use of fast chargers [6,10,11]. Few have however analyzed in depth the actual usage of fast chargers at a national scale for longer time periods, based on datasets from the fast charge operators.…”

“…The allowed power varies with the actual battery temperature and the battery state of charge (SOC). Fast charging is slower in low ambient temperatures, as the battery's chemical properties limits the speed of movement of ions through the battery materials [16,21]. The battery charge power is also limited to preserve battery life when the batteries are overheated [17,19], for instance due to high-speed driving in warm weather.…”

Assessment of Low‐Frequency Magnetic Fields Emitted by DC Fast Charging Columns

“…Five DC fast charging columns, available on the market, were tested inside the Interoperability Laboratory of the Joint Research Center (Ispra, Italy). The chargers were equipped with combined charging system and CHAdeMO charging options and they were connected to the JRC electricity grid providing 400 V AC by means of a max 125 A, 50 Hz wall socket [Trentadue et al, 2018]. Table 1 describes the main technical specifications of the devices under test.…”

Experimental Verification of Use of Vacuum Insulating Material in Electric Vehicle Headliner to Reduce Thermal Load

“…The main obstacle to the commercialization of electric vehicles (EVs)-environmentally friendly cars-is that they offer lower mileage for a single charge when compared with the mileage of internal combustion engines [1][2][3][4]. For vehicles with internal combustion engines, the vehicle cooling operation reduces fuel consumption by 20-30%, thereby reducing the mileage by 2%-30%; on the other hand, in the case of heating, fuel consumption is not affected as the waste heat of the engine is used [5][6][7].…”