Crucial Issues in Logistic Planning for Electric Vehicle Battery Application Service

Haiming Wang 1,2, Haifeng Xu 2, Alex K. Jones2 1 Hebei Normal University of Science and Technology, China

2 Department of Electrical and Computer Engineering, University of Pittsburgh, USA grant1207@sohu.com, haw36@pitt.edu

Abstract—Based on a brief introduction of typical battery features, several crucial issues in logistic planning for Electric Vehicle (EV) battery applications are discussed in this paper. The obvious issues include the access of battery charging stations, the accessibility of emergence swapping, and the monitoring of batteries at charging stations on network. Standardization of the battery and energy exchange technology would accelerate the popularity and market penetration of EVs. Some barriers to widespread EVs include issues related to battery recycling and environmental protection. Furthermore, training and certification are required to prepare the workforce for EV battery service. Finally a battery management information system is systematically a very important factor for supporting battery manufacturing, battery supply chains, battery charging services, battery swapping services, recycling regulations, safety of transportation, and insurance markets.

Keywords-EV battery application; Crucial issues; Charging stations; Swap stations; Service standardization; Workforce training; Battery management information system

I. INTRODUCTION Recently, there has been a surge of interest in the

manufacture and sale of Electric Vehicles (EVs) due to their advantages of environmental friendliness compared to traditional petroleum-based vehicles. With the development of the EV, there are several crucial issues that must be discussed in order to make EV battery service sustainable. Among them, an obvious issue is the accessibility of EV batteries used by their customers. For example, according to the parameters of some kinds of EVs, the distance that a fully charged EV battery supports is usually 120~320 kilometers per charge, which means without a convenient, cost effective method to quickly refill EV battery’s energy, the use of EVs would be limited within a fairly small area such as a city [1, 2].

There are many types of battery that have potential for use in EVs, such as lead-acid (LA) batteries, Nickel-metal hydride (NiMH) batteries, and Lithium-ion (Li-ion) batteries. Lithium-ion and valve regulated LA (VRLA) batteries are presently the two prevalent kinds of batteries currently used in EVs. VRLA-based EVs are popular for public transportation applications. However, most of the new EVs tend to be installed with Lithium-ion batteries due to the following advantages including: 1) a much lighter weight than other energy-equivalent types of batteries; 2) a higher open circuit voltage; and 3) no memory effects [3-5].

Based on a brief introduction of the features of Li-ion and VRLA batteries, several crucial issues in logistic planning and decision making related to battery service for

EVs are discussed in this paper. These issues are the accessibility of EV battery service, standardization of the system for battery maintenance and service, methods for battery recycling and environmental protection, workforce training and certification, and construction of a battery management information system.

II. EV BATTERY CAPABILITIES AND ISSUES VRLA batteries have traditionally been used in EVs due

to their mature/proven technology and low cost. According to the data from the new developments in EV batteries [6], such as the Electric Vehicle Traction Dry Cell (circa 2009) as the recharge time from 0 to 90% charge in 4 hours and to 100% is 6 hours. Additionally, the lifespan of the battery is rated at 600 charges when discharged to 20% (similar to running a petrol-based vehicle down to the reserve tank/capacity). The lifetime increases by 25% if only 50% of the battery is used and 46% if only 20% of the battery is used. However, it is likely that these kinds of batteries have a shorter lifespan than the EV itself. Typically the deep-cycle VRLA batteries need to be replaced every 3 years [7]. More importantly, the EV drivers will not tolerate spending several hours waiting at charging stations in order to recharge their EV batteries, even if speed chargers for VRLAs are employed unless a 2-3 order of magnitude improvement is possible.

Use of Li-ion batteries dominates the most recent group of EVs in development. Li-ion batteries are widely known from their applications in laptops and other consumer electronics due to their high energy density (e g. 200Wh/kg), good power density, and 80 to 90% charge/discharge efficiency [8]. The disadvantages of traditional Li-ion batteries are limited charging cycles, significant degradation with aging, and higher internal resistance than that of other kinds of batteries. Although new developments have shown some variants of Li-ion, such as the Lithium iron phosphate batteries [9], have the characteristics of fire resistance, environmental friendliness, rapid charging, and longer lifespan, the variants of Li-ion would face the similar problems of constructing charging stations, swap stations, recycling service, etc.

According to the features of EV batteries discussed above, the crucial deployment issues for EV battery technology are reflected in the problems of limited service infrastructure and technology. As previously mentioned, for EV vehicles to become mainstream, issues such as inspections of the battery charging, battery swapping, tracking, leasing, etc must be handled. Thus, the accessibility of EV is directly related to the battery service procedure of

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charging spent batteries and/or swapping out a discharged battery for a charged battery.

III. ACCESSIBILITY OF EV BATTERY SERVICE Although there are several interesting proposals to

improve the interval between charging EV batteries, such as wireless charging, charging during EV’s movement, battery charging stations and battery swap stations are the two practical methods to solve the EV energy supply problems.

In order to allow for EVs to effectively use the highway (without running out of charge), the number charging stations, or swap stations deployed along the highways, would be issue of analysis and planning just like the number of conventional fueling stations along the main roads is today.

The number of charging stations in the future depends on the total length of highways or main roads EVs would use as they become popular. If the line density requirement of battery charging stations is evaluated respectively as one station /50km, /75km, /100km, 125km, or /150km, along the highways, the expected number of the charging stations, or swap stations follows the trend shown in Figure 1.

Figure 1. Numerical evaluation of charging stations or swap stations

For example, in terms of the data in 2008 in China, the total length of highways is 1,995,000km [10]. Among them, the length of high-speed highway is 65,000km. In 2020, total length of highways is projected to extend up to 3,000,000km. From Figure 1, it can be concluded that the expected number of charging/swap stations that should be deployed would increase from approximately 20,000 stations up to 60,000 stations in the next 10 years. The current statistics shows that there are currently about 96,000 conventional gas stations in China in 2008 [11].

A. Accessibility through the Emergence of Swapping Battery swapping is a feasible method to increase the

accessibility of the EV batteries. It provides an alternative to recharging, and allows users to exchange their drained or nearly drained batteries with fully charged batteries in exchange stations [12]. For this method to be successful it would require the emergence of battery power supply chain,

the standardization of EV battery package connectors, etc. The quick replacement of batteries is obviously a necessity for this practical solution.

By swapping batteries, the consumer is no longer concerned with cost of batteries and battery warranties. The present state of the art battery maintenance and service would be taken care of by professionals and dedicated companies with their fees built into the cost of the replacement cells. This includes periodic battery maintenance and replacement, technology infrastructure and quality inspection, and space for overnight charging if drivers do not have garages. Moreover, it will save time for drivers as each swap is a procedure of high efficiency, and faster than charging or even the refilling process of the conventional vehicles using fuel. This can be accelerated even further through application of technologies like RFID for item tracking and payment.

Besides the benefits to EV consumers, swap stations would promote the development of a renewable energy market, and healthy competition among battery makers. The distributed swap stations could also provide a facility for energy grid storage that could be used to mitigate the intermittency of generation from renewable energy sources such as solar, wind, and geothermal energy. These swap stations could purchase cheap energy during excess generation and sell back energy when the renewable energy under generates or the grid sees peak loads.

Consequently, swap stations and standardization of battery manufacturing provide an incentive system for driving down the costs of EVs through competition among the battery makers. With the assistance of legislation to promote the development of a swapping infrastructure, and the standardization in swapping technology and management, swap stations would do away with the need for costly, unmanageable, and resource-intensive public charging, and would play a more important role in national energy storage area.

B. Accessibility of Smart Monitoring Batteries in Charging Stations Monitoring and round the clock management of huge

amounts of EV batteries in charging stations are new challenges that must be solved before EVs will gain significant market penetration. In part this is due to the need for trained attendants at EV charging stations to confirm each and every battery (package) if on good condition before its swapping, reinstallation, or delivery. Unlike traditional filling stations where attendants need not to take the responsibility of verifying the gasoline quality prior to refilling each tank. Thus, smart monitoring of EV battery parameters and performance is very important in charging stations or swapping stations.

Generally there are many factors that should be considered in planning these kinds of charging stations. The testing parameters for verifying the battery is briefly introduced in Table I.

The smart monitoring system for batteries is one of many important integrated subsystems in an information system designed to manage the EV battery service infrastructure. In

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order to deal with monitoring a huge amount of batteries, which requires processing continuous sampling data, some information technologies are necessary in charging stations and swap stations, including the monitoring technology connected to the network, and data processing through cloud computing. A block diagram representation of the monitoring battery system is shown in Figure 2. This kind of system is somewhat similar to the remote management of VRLA battery strings [13]. However, in an EV battery infrastructure, most of the data access procedures are necessary for the delivery response and real time purpose, and some fields of their database would be shared with the whole system to allow battery tracking.

TABLE I FACTORS REQUIRED TO VERIFY EACH BATTERY AT CHARGING STATIONS

Name Content

Battery ID History profile of battery, trace for its lifespan, management

Visual condition

Integrity for evidence of corrosion, cover distortion, etc.

Voltages Charging voltage, terminal voltage Internal

resistances Internal ohmic values, internal connecting resistance

Currents Charging current, current of end charging Charged

status At least 90% of rated capacity, or 100% rated capacity

Temperature Temperature varies during charging procedure

In Figure 2, the Battery Monitoring & Management Unit

(BMMU) checks the battery charging status and continuously monitors and diagnoses all Charging Batteries in the system, and automatically decides if one is right for delivery or replacement according to its performance characteristics. In charging stations, the data is communicated over the Ethernet to a central database for improved characterization and information retrieval.

Figure 2. Block diagram of smart monitoring batteries on network

The secondary data processing is performed by cloud computing on Internet using information stored in the database systems. It records and composes the history profile of each battery, provides a decision analysis of battery supply chains, and supports technology responses conducted by the Center of Services.

IV. STANDARDIZATION OF BATTERY SERVICE SYSTEM The standardization of the battery service is a key

problem regarding the interoperability of compatible EV batteries, which would allow for the battery exchange without technology barriers between different brands of EVs, different swap stations, different charging stations, as well as different energy exchange infrastructures.

The obvious issue is to standardize the swapping component of EV batteries. For example, the dimensions of battery packages, the connector of battery packages, the voltage and internal resistance of battery cells and strings, must meet the requirement of battery exchange.

The standardization would also be classified by the energy storage or applied capacity requirement for renting batteries to travel different distances. In other words, if these standards were developed and followed by the different vehicle manufactures, EVs could market penetration, and in turn benefit consumers and our living environment.

V. BATTERY RECYCLING AND ENVIRONMENTAL PROTECTION

In the 21st century, concerns over the environmental impact from petroleum-based vehicles encouraged a focus on EVs and green/renewable energy sources. Although it is a common knowledge that popular EVs are low emission, the disposal of batteries in landfills would create a new environmental pollution. If the huge amount of expired EV batteries could not be recycled and properly processed, these batteries would become a source of environmental hazard we have not previously experienced. For example, if the lead compounds from VRLAs were accidentally ingested, that may cause severe health problems. The improper procedure of the recycling lead compounds can also be dangerous because the high temperature can easily produce toxic metal fume, vapor, or dust [14].

Li-ion batteries are not as serious as a direct environmental hazard, because the metals in Li-ion batteries - cobalt, copper, nickel and iron - are considered safe for landfills or incinerators. However, the mass disposal of huge amounts of Li-ion batteries is wasteful in terms of running out of our living space, as well as metal material resources and may have environmental impacts that have not yet been discovered.

With the development of the EV, battery recycling will likely become a huge factor and may require oversight. Regardless, it will require battery factories, vendors, and consumers to take appropriate social responsibilities for recycling and environmental protection.

VI. WORKFORCE TRAINING AND CERTIFICATION The emergence of battery swapping stations or charging

stations would provide a lot of new employment opportunities for certificated workers who are professionals at EV battery service, service to EVs and energy exchange with national power grid. A certificated workforce with professional training in EV battery service is a necessary condition of sustainable EV development. Thus, it is important for engineering schools to develop action plans for

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addressing the critical challenges in assuring an ample supply of future EV battery and energy engineers. In terms of the data on the number of battery service stations from Figure 1, the numbers of engineers, and technicians at swap stations or charging stations are estimated as in Figure 3, in which each station technical team would at least employ 4~5 people (technicians and engineers).

Figure 3. Numerical evaluation on battery technical worker

If all employment aspects were fully considered such as, the appropriate work hours per person each year according to standard labor laws, and the battery charging monitoring without M2M smart and automation technology, the practical need for battery charging and measurement operation employees are double or triple of the estimation from the figure. That is to say the engineering schools would plan to train 300,000~550,000 engineers and technicians in this area in the next few years.

VII. OTHER ASPECTS AND CONCLUSIONS Based on the battery parameter discussion, the issues

from technology, standardization, workforce, and environmental protection are described in order to promote the accessibility of EV products. In addition to the previous discussion, the other related aspects of EV battery services are briefly shown in Figure 4.

Figure 4. Energy flow and battery flow

With a sign of energy flow and battery flow in Figure 4, it is necessary to build an interface between the two through technology standardization. Such an interface could create opportunities to link with individual or large scale renewable energy generation and could help mitigate what is currently a possible energy crisis in the electricity supply market.

EVs also create a new source of demand for electrical energy generation. For example, growth in energy consumption of transportation is correlated with economic growth measured by Gross Domestic Product (GDP). Figure 5 projects the correlation between the average annual growth in OECD and Non-OECD GDP and transportation sector delivered energy use from 2006 to 2030 [15]. The energy consumption of EV transportation is definitely included in the projection of the energy requirements of the transportation sector, although it has less impact on GDP today.

A powerful national Battery Management Information System (BMIS) is also a very important factor to support battery factories, battery supply markets, battery charging stations, battery swap stations, battery recycling stations, and insurance markets. The BMIS would help to balance and secure the profits from different components of the EV and related support industry. A BMIS should acquire and update data on battery information from the ERP system owned by different enterprise areas, in which the database systems are developed using unique data format for compatibility.

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Product

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Freight Transportation

Passenger Transportation

Figure 5. Average annual growth in OECD and Non-OECD GDP and transportation sector delivered energy use, projected from 2006 to 2030

In conclusion, with the increasing application of EV batteries, several crucial issues are highlighted for the accessibility of battery exchange and energy exchange. As a case study, approximately 20,000~60,000 charging stations or swap stations would need to be built along highways to solve the EV energy supply needs in China. In the charging stations, smart monitoring systems would be systematically developed and employed to monitor the huge amount of charging batteries on the network. Standardization of battery exchange interface facilities and battery application parameters would facilitate EV development by allowing the concept of battery swapping. Battery recycling is highlighted as an issue of environmental protection as the battery has a

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shorter lifespan than the EV itself. In the educational community, engineering schools would need to launch professional training programs for preparing a workforce of 300,000~550,000 engineers and technicians. A powerful national battery management information system would benefit EV battery service.

REFERENCES [1] http://www.fueleconomy.gov/feg/evtech.shtml [2] http://www.chery.cn/2009/public/detail.jsp?id=7397 [3] K. Suzuki, K. Nishida and M. Tsubota, Valve-regulated lead/acid

batteries for electric vehicles: present and future [J], Journal of Power Sources, Volume 59, Issues 1-2, March-April 1996, Pages 171-175

[4] Masataka Wakihara, Recent developments in lithium ion batteries [J], Materials Science and Engineering: R: Reports, Volume 33, Issue 4, 1 June 2001, Pages 109-134

[5] Electric vehicle battery, http://en.wikipedia.org/wiki/Electric_vehicle_battery

[6] EV700, EV Traction Dry Cell, Gel, Advanced AGM, and standard AGM Batteries and Power Blocks. http://www.discover-energy.com/files/shared/Discover_Battery_Guide_Jan_2009_1.pdf

[7] Wang Hai-ming; Zhang Fang; Zhang Hai-tao; Liu Feng. Application of VRLA Batteries at Power Systems in Network Center Room, Telecom Power Technology [J], 2008/04:64-68

[8] Wang Haiming, Zheng Shengxuan, Liu Xingshun, Characteristics and Applications of Lithium Ion Cells [J], ELECTRIC AGE 2004

3 132-134 [9] A123 Inks Deal to Develop Battery Cells for GM Electric Car,

http://www.xconomy.com/boston/2007/08/10/a123-inks-deal-to-develop-battery-cells-for-gm-electric-car/

[10] http://www.chinahighway.com/news/2010/391810.php [11] http://www.20087.com/2010-

01/R_2009jiayouzhanyanjiuBaoGao.html [12] http://www.stuff.co.nz/stuff/4695844a6502.html [13] Katsuhide Ohnuki, Tatsuo Sakai, Yuji Kawagoe. Evolution of VRLA

battery maintenance technologies at NTT [C]. INTELEC 2007. Sep. 30 2007 ~ Oct. 4, 2007: 90-96

[14] Material Safety Data Sheet for Lead-Acid Batteries, Revision 1/1/2009, HAWKER POWERSOURCE, Inc.

[15] International Energy Outlook 2009, Energy Information Administration, Office of Integrated Analysis and Forecasting U.S. Department of Energy, www.eia.doe.gov/oiaf/ieo/index.html.

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