Ev Charger Technologies

EV charging technologies in China and the United States are broadly similar. In both countries, cords and plugs are the overwhelmingly dominant technology for charging electric vehicles. (Wireless charging and battery swapping have at most a minor presence.) There are differences between the two countries with respect to charging levels, charging standards and communications protocols. These similarities and differences are discussed below.

A. Charging Levels

In the United States, a great deal of EV charging takes place at 120 volts using unmodified home wall outlets. This is generally known as Level 1 or “trickle” charging. With Level 1 charging, a typical 30 kWh battery takes approximately 12 hours to go from 20% to a nearly full charge. (There are no 120 volt outlets in China.)

In both China and the United States, a great deal of EV charging takes place at 220 volts (China) or 240 volts (United States). In the United States, this is known as Level 2 charging.

Such charging may take place with unmodified outlets or specialized EV charging equipment and typically uses about 6–7 kW of power. When charging at 220–240 volts, a typical 30 kWh battery takes approximately 6 hours to go from 20% to a nearly full charge.

Finally, both China and the United States have growing networks of DC fast chargers, commonly using 24 kW, 50 kW, 100 kW or 120 kW of power. Some stations may offer 350 kW or even 400 kW of power. These DC fast chargers can take a vehicle battery from 20% to a nearly full charge in times ranging from roughly one hour to as little as 10 minutes.

Table 6: Most common charging levels in U.S.

Source: U.S. Department of Energy

B. Charging Standards

i. China

China has one nationwide EV fast charging standard. The US has three EV fast charging standards.

The Chinese standard is known as China GB/T. (The initials GB stand for national standard.)

China GB/T was released in 2015 after several years of development.124 It is now mandatory for all new electric vehicles sold in China. International automakers, including Tesla, Nissan and BMW, have adopted the GB/T standard for their EVs sold in China. GB/T currently allows fast charging at a maximum of 237.5 kW of output (at 950 V and 250 amps), though many

Chinese DC fast chargers offer 50 kW charging. A new GB/T will be released in 2019 or 2020, which will reportedly upgrade the standard to include charging up to 900 kW for larger commercial vehicles. GB/T is a China-only standard: the few China-made EVs exported abroad use other standards.125

In August 2018, the China Electricity Council (CEC) announced a memorandum of understanding with the CHAdeMO network, based in Japan, to jointly develop ultra-fast charging. The goal is compatibility between GB/T and CHAdeMO for fast charging. The two organizations will partner to expand the standard to countries beyond China and Japan.126

ii. United States

In the United States, there are three EV charging standards for DC fast charging: CHAdeMO, CCS SAE Combo and Tesla.

CHAdeMO was the first EV fast-charging standard, dating to 2011. It was developed by Tokyo

Electric Power Company and stands for “Charge to Move” (a pun in Japanese).127 CHAdeMO is currently used in the United States in the Nissan Leaf and Mitsubishi Outlander PHEV, which are among the highest-selling electric vehicles. The Leaf’s success in the United States may be ELECTRIC VEHICLE CHARGING IN CHINA AND THE UNITED STATES

ENERGYPOLICY.COLUMBIA.EDU | FEBRUARY 2019 |

due in part to Nissan’s early commitment to roll out CHAdeMO fast-charging infrastructure at dealerships and other urban locations.128 As of January 2019, there were over 2,900 CHAdeMO fast chargers in the United States (as well as more than 7,400 in Japan and 7,900 in Europe).129

In 2016, CHAdeMO announced it would upgrade its standard from its initial charging rate of 70

kW to offer 150 kW.130 In June 2018 CHAdeMO announced the introduction of 400 kW charging capability, using 1,000 V, 400 amp liquid-cooled cables. The higher charging will be available to meet the needs of large commercial vehicles such as trucks and buses.131

A second charging standard in the United States is known as CCS or SAE Combo. It was released in 2011 by a group of European and US auto manufacturers. The word combo indicates that the plug contains both AC charging (at up to 43 kW) and DC charging.132 In

Germany, the Charging Interface Initiative (CharIN) coalition was formed to advocate for the widespread adoption of CCS. Unlike CHAdeMO, a CCS plug enables DC and AC charging with a single port, reducing the space and openings required on the vehicle body. Jaguar,

Volkswagen, General Motors, BMW, Daimler, Ford, FCA and Hyundai support CCS. Tesla has also joined the coalition and in November 2018 announced its vehicles in Europe would come equipped with CCS charging ports.133 The Chevrolet Bolt and BMW i3 are among the popular EVs in the United States that use CCS charging. While present CCS fast chargers offer charging at around 50 kW, the Electrify America program includes fast charging of 350 kW, which could enable a nearly complete charge in as little as 10 minutes.

The third charging standard in the United States is operated by Tesla, which launched its own proprietary Supercharger network in the United States in September 2012.134 Tesla

Superchargers typically operate at 480 volts and offer charging at a maximum of 120 kW. As

of January 2019, the Tesla website listed 595 Supercharger locations in the United States, with an additional 420 locations “coming soon.”135 In May 2018, Tesla suggested that in the future its Superchargers might reach power levels as high as 350 kW.136

In our research for this report, we asked U.S. interviewees whether they considered the lack of a single national standard for DC fast charging to be a barrier to EV adoption. Few answered in the affirmative. The reasons that multiple DC fast charging standards are not considered to be a problem include:

● Most EV charging takes place at home and work, with Level 1 and 2 chargers.

● Much of the public and workplace charging infrastructure to date has used Level 2 chargers.

● Adaptors are available that allow EV owners to use most DC fast chargers, even if the EV and charger use different charging standards. (The main exception, the Tesla supercharging network, is only open to Tesla vehicles.) Notably, there are some concerns about the safety of fast-charging adaptors.

● Since the plug and connector represent a small percentage of the cost of a fast-charging station, this presents little technical or financial challenge to station owners and could be compared to the hoses for different octane gasolines at a fueling station. Many public charging stations have multiple plugs attached to a single charging post, allowing any type of EV to charge there. Indeed, many jurisdictions require or incentivize this.ELECTRIC VEHICLE CHARGING IN CHINA AND THE UNITED STATES

38 | CENTER ON GLOBAL ENERGY POLICY | COLUMBIA SIPA

Some carmakers have said that an exclusive charging network represents a competitive strategy. Claas Bracklo, head of electromobility at BMW and chairman of CharIN, stated in 2018, “We have founded CharIN to build a position of power.”137 Many Tesla owners and investors consider its proprietary supercharger network a selling point, although Tesla continues to express willingness to allow other car models to use its network provided they contribute funding proportional to usage.138 Tesla is also part of CharIN promoting CCS. In November 2018, it announced that Model 3 cars sold in Europe would come equipped with CCS ports. Tesla owners can also purchase adaptors to access CHAdeMO fast chargers.139

C. Charging Communication Protocols Charging communication protocols are necessary to optimize charging for the needs of the user (to detect state of charge, battery voltage and safety) and for the grid (including

distribution network capacity, time-of-use pricing and demand response measures).140 China GB/T and CHAdeMO use a communication protocol know as CAN, while CCS works with the PLC protocol. Open communications protocols, such as the Open Charge Point Protocol (OCPP) developed by the Open Charging Alliance, are becoming increasingly popular in the United States and Europe.

In our research for this report, several U.S. interviewees cited the move toward open communications protocols and software as a policy priority. In particular, some public charging projects that received funding under the American Recovery and Reinvestment Act (ARRA) were cited as having chosen vendors with proprietary platforms that subsequently experienced financial difficulties, leaving broken equipment that required replacement.141 Most cities, utilities, and charging networks contacted for this study expressed support for open communications protocols and incentives to enable charging network hosts to seamlessly switch providers.142

D. Costs

Home chargers are cheaper in China than in the United States. In China, a typical 7 kW wall mounted home charger retails online for between RMB 1,200 and RMB 1,800.143 Installation requires additional cost. (Most private EV purchases come with charger and installation included.) In the United States, Level 2 home chargers cost in the range of $450-$600, plus an average of roughly $500 for installation.144 DC fast charging equipment is significantly more expensive in both countries. Costs vary widely. One Chinese expert interviewed for this report estimated that installing a 50 kW DC fast-charging post in China typically costs between RMB 45,000 and RMB 60,000, with the charging post itself accounting for roughly RMB 25,000 – RMB 35,000 and cabling, underground infrastructure and labor accounting for the remainder.145 In the United States,  DC fast charging can cost tens of thousands of dollars per post. Major variables affecting the cost of installing DC fast charging equipment include the need for trenching, transformer upgrades, new or upgraded circuits and electrical panels and aesthetic upgrades. Signage, permitting and access for the disabled are additional considerations.146

E. Wireless Charging

Wireless charging offers several advantages, including aesthetics, time saving and ease of use.

It was available in the 1990s for the EV1 (an early electric car) but is rare today.147 Wireless EV charging systems offered online range in cost from $1,260 to around $3,000.148 Wireless EV charging carries an efficiency penalty, with current systems offering charging efficiency of around 85%.149 Current wireless charging products offer power transfer of 3–22 kW; wireless chargers available for several EV models from Plugless charge at either 3.6 kW or 7.2 kW, equivalent to Level 2 charging.150 While many EV users consider wireless charging not worth the additional cost,151 some analysts have forecast the technology will soon be widespread, and several carmakers have announced they would offer wireless charging as an option on future EVs. Wireless charging could be attractive for certain vehicles with defined routes, such as public buses, and it has also been proposed for future electric highway lanes, though high cost, low charging efficiency and slow charging speeds would be drawbacks.152

F. Battery Swapping

With battery swapping technology, electric vehicles could exchange their depleted batteries for others that are fully charged. This would dramatically shorten the time required to recharge an EV, with significant potential benefits for drivers.

Several Chinese cities and companies are currently experimenting with battery swapping, with a focus on high-utilization fleet EVs, such as taxis. The city of Hangzhou has deployed battery swapping for its taxi fleet, which uses locally made Zotye EVs.155 Beijing has built several battery-swap stations in an effort supported by local automaker BAIC. In late 2017, BAIC announced a plan to build 3,000 swapping stations nationwide by  2021.156 The Chinese EV startup NIO plans to adopt battery-swap technology for some of its vehicles and announced it would build 1,100 swapping stations in China.157 Several cities in China—including Hangzhou and Qingdao—have also used battery swap for buses.158

In the United States, discussion of battery swapping faded following the 2013 bankruptcy of Israeli battery-swap startup Project Better Place, which had planned a network of swapping stations for passenger cars.153 In 2015, Tesla abandoned its swapping station plans after building only one demonstration facility, blaming lack of consumer interest. There are few if any experiments underway with respect to battery swapping in the United States today.154 The decline in battery costs, and perhaps to a lesser extent the deployment of DC fast-charging infrastructure, have likely reduced the attraction of battery swapping in the United States.

While battery swapping offers several advantages, it has notable drawbacks as well. An EV battery is heavy and typically located at the bottom of the vehicle, forming an integral structural component with minimal engineering tolerances for alignment and electrical connections. Today’s batteries usually require cooling, and connecting and disconnecting cooling systems is difficult.159 Given their size and weight, battery systems must fit perfectly to avoid rattling, reduce wear and keep the vehicle centered. Skateboard battery architecture common in today’s EVs improves safety by lowering the vehicle’s center of weight and improving crash protection in the front and rear. Removable batteries located in the trunk or elsewhere would lack this advantage. Since most vehicle owners charge mainly at home or ELECTRIC VEHICLE CHARGING IN CHINA AND THE UNITED STATES at work, battery swapping would not necessarily resolve the charging infrastructure issues— it would only help address public charging and range. And because most automakers are unwilling to standardize battery packs or designs—cars are designed around their batteries and motors, making this a key proprietary value160—battery swap might require a separate swapping station network for each car company or separate swapping equipment for different models and sizes of vehicles. Though mobile battery swapping trucks have been proposed,161  this business model has yet to be implemented.