Charles W. Botsford, P.E. and Andrea L. Edwards AeroVironment, Inc. 800 Royal Oaks Drive, Suite 210 Monrovia, CA An Integrated Global Philosophy of EV Charging

Electric Vehicle (EV) charging methods have evolved over the past two decades to reflect the radical evolution of EVs and have varied in usefulness to the EV driver. DC fast charging, which made a brief appearance in the late 90s, is now a valuable EV market enabler, but suffers from the political and technical disagreements of multiple protocols. Globally, EV charging will evolve further to meet the demands of the new consumer EVs and the demands of the EV driver. This paper proposes an integrated global philosophy to meet these demands. Abstract

A Brief History The 1990s saw the first real introduction of EVs with the GM EV-1 and others such as the Toyota RAV-4EV and the Chevy S-10 to satisfy air quality reduction requirements (not to satisfy a new market for EVs focused on EV drivers). Political and technical disagreements imposed different charger requirements for the same class of EV – finally resolved. In the late 1990s, AeroVironment, Inc. developed a 60kW direct current (DC) fast charger and worked with UL for listing as a method to enhance EV driver experience. Now we see multiple standards for DC fast charging in US alone. Europe and China have different DC fast charging standards. This is a negative impact on the EV driver and for the market as a whole. Bi-Directional DC Fast Charger, c.1998

Future EV/PHEV Driver Needs PHEVs with 50-mile EV range (18kWh pack) 16A Level 1 or Level 2 charging at home & workplace No DC fast charging EVs with 125-mile range (43kWh pack) 30A Level 2 charging at home & workplace 250 DC fast charging (10-minute charge sessions) EVs with 250-mile range (90kWh pack) 30A Level 2 charging at home & workplace 150 DC fast charging (30-minute charge sessions) kWh to Travel 100 miles Gasoline Vehicle, 50 mpg68 Fuel Cell Vehicle, 47 miles/kg H271 EV, 3.3 miles/kWh30

Chargers to Satisfy EV Drivers In-Trunk Cordset 120/240 VAC for US and Japan (100/200 for Japan) VAC for rest of world Residential and MUD EVSE 16A Level 1 for PHEVs 30A Level 2 for EVs Workplace EVSE 16A Level 1 16A to 30A Level 2 Corridor Charging Stations 150kW DC 250kW DC TurboCord Dual Voltage Cordset Residential EVSE

Practical Limits to Power The Utilities Residential – 7kW In North America and other areas, utilities use 200kVA single phase distribution transformers to power five homes (typical) In Europe the utilities typically use 3-phase transformers MUDs – 3.3kW per port Workplace – 7kW per port Corridor Depends on the transmission line May need GW-level stations Single-phase Transformer

Practical DC Fast Charging Why ≤50kW (and lower) is a Bad Idea Based on the charge profile at right, a Nissan Leaf would receive 11kWh in 23 minutes, equating to about 36 miles of range, Effectively 1.6 miles range/minute of charging For long distance travel purposes, more time will be spent diverting from the highway to get to the charger and then charging, than actual driving time DC fast charging must maximize miles/minute for realistic EV travel Source: mynissanleaf.com

Practical Dwell Times Charging dwell time is a key metric for two reasons 1.Long dwell times mean less percent time on the road for EV drivers 2.Long dwell times translate to more ports required to satisfy traffic counts High power, low dwell time minimizes number of ports, EV driver queueing time, and charge time to drive time ratio 30-minute DC Fast Charging 5 miles range/minute Requires: 150kW/port power levels No change to battery pack 10-minute DC Fast Charging 10 miles range/minute Requires: 200+kW/port power levels Battery packs that can accept 6c charge rates

Practical Application Case Study – LA to Vegas (250 Miles) Peak Traffic Count – weekend, one direction = 4,320 sedans/hr 5% EV penetration by 2025 = 216 EV/hr, or 36 EV/10 min, or 108/30 min 125-Mile Range EV w/10-minute DC fast Charging (2 charges/250 miles) 2025 traffic requires 72 ports per corridor at 200kW = 14.4MW 250-Mile Range EV w/30-minute DC fast Charging (1 charge/250 miles) 2025 traffic requires 108 ports per corridor at 150kW = 16.2MW Either type of EV requires a many MW corridor station to satisfy EV driver needs. The 125-mile EV, with 10-minute fast charging, would require fewer ports and be closer to the “gas station experience” Hundreds of MW power levels for high power DC charging stations required when EVs reach high penetration rate in 2040 and beyond

Conclusions Residential charging, and to a lesser extent other long dwell time charging venues such as workplace, will remain the dominant location for EV drivers because of convenience, pricing, and the potential for grid services, which ultimately can benefit the driver DC fast charging is an important capability for the EV driver. The two best cases for future EVs, 125- mile or 250-mile range, have advantages and disadvantages. For example: The 250-mile EVs will require a longer charge time, but the longer range minimizes driver range anxiety. The 125-mile EV allows ten-minute charging, which is great for the driver. Both types of EVs will require high power corridor charging infrastructure

Charles Botsford AeroVironment, Inc.