研发中心 e-Newsletter 2014年3月份

Battery swap for mass market Electric Vehicle: Solution or Road Block

Tesla Motors in late June 2013 demonstrated how its service station (Tesla Station) could accomplish two battery swaps for the Model S in the time it takes to fill a gas tank.

In February 2014 it projected sales of over 35,000 Model S in 2014, a 55% increase over 2013. Weekly production is expected to increase from 600 cars to about 1,000 cars by end of the year. It plans to sell the Model S in China for the same price as in the US, has recently announced leasing and financing options in European markets, and plans to start shipping right-hand drive models to the UK, Japan, Hong Kong and Australia this spring.

Model S is not for mass market yet
In Hong Kong, Model S with the 60kWh battery option will start at HK$579,000. Model S with the 85kWh battery option will start at HK$657,000, and Model S Performance 85 will start at HK$761,800. These prices do not include the First Registration Tax, which is currently waived for electric vehicles.

Battery swap technique works for Tesla by design
The Model S was designed for quick battery swaps. It has been built ‘connected’ for automatic payment and battery sway only work in Tesla Station. The company is moving ahead with plans to open Tesla Stations in California. Each station uses the same machinery employed at the Tesla factory to swap a Model S battery pack in around 90 seconds.

Every battery in Model S ages over time to lose its driving range and value. Tesla has to work out reasonable deals with owners who signed up the battery swap program. The company previously said it would charge owners $60 to $80 a month for the service, though Forbes speculated that owners would be required to pick up their original battery packs at some point.

Hurdles for Battery swap in mass market
Better Place the electric car infrastructure startup, filed for bankruptcy in May 2013. Its business model from 2007 was built around an electric car with a swappable battery, and the installation of both battery swap stations and battery chargers around a designated area. Customers pay for the electricity to charge the car via a subscription service (like cell phone minutes) and the electric cars themselves were supposed to be highly subsidized. Though the battery swapping technique could be extremely useful to extend the range of electric vehicles and to reduce range anxiety associated with electric vehicles, the hurdles in the actual business seemed too difficult to overcome.

Yes, there were major hurdles in the mass market. First, vehicles have to be compatible with battery swapping. This means batteries must be located on the underside of the vehicle. Second, the battery swapping station would have to stock several of every type of electric vehicle battery. There was no standardization for battery size or type at the time. Therefore the station must have all batteries on hand in business. Finally, the station must stay current with all of the new electric vehicles produced. Keeping batteries in stock for all electric vehicles would almost certainly mean a warehouse sized swapping station. This business model required a huge capital investment and depended on the wider support of compatible vehicles. Other limiting factors included the objection by drivers to older batteries and the very small business volume only by customers making long trips. 

Better Place has not been successful in convincing auto makers to enable their car batteries to be swapped out. When launching its service in Israel, it only offered one unimpressive car from Renault.

Even today, vehicle manufacturers have never agreed to any common battery standards.
First of all is that battery technology is still evolving. More importantly, Integrated (non swappable) battery design helps to increase chassis frame stiffness and doesn’t increase vehicle weight. These are constraints to vehicle manufacturers when planning for the standard battery design.

Battery swap solution
In places where dedicated parking is scarce, such as China, Spain, or the UK, drivers must rely more on shared public charging stations. A low capacity overnight charging scenario may be infeasible where parking is scarce, unless they have access to dedicated Electric Vehicle Supply Equipment (EVSE)-equipped parking spots. Then battery swapping would be alternative to the low capacity charging.

A potential benefit of battery swapping is that swap station operators can charge batteries at the best times of day to minimize the impact on peak power demand. Battery swapping may allow vehicle owners to “recharge” quickly on-the-go, and could serve as an alternative approach to controlled charging. Swap stations could benefit regions where high density and parking constraints limit access to private, dedicated low capacity charging. In such locations, battery swap stations may prove viable alternatives to low capacity and high capacity public charging stations. Battery swapping has been deployed on a limited basis for fleets in Chinese cities.

Sihui Electric Bus Charging/Battery Swapping Station, the largest of its kind in Beijing, was officially put into operation on Sept 16, 2013. The station is located at Chaoyang District of the city. According to State Grid Beijing Municipal Electric Power Company, Beijing has built 64 charging stations for electric vehicles, covering all its districts. It can provide charging services for over 3000 electric vehicles, including electric buses, taxis, sanitation trucks, passenger vehicles and comprehensive vehicles.

電動車鋰離子電池發展的路缐圖

電動車普及的關鍵
美國電動車大廠特斯拉(Tesla) ，在全球電動車市場引領風騷，除了乘勢”電動環保車”的訴求易討好之外，評論者和用戶以為Tesla 電動車的表現，才是真正的原因（下面表格引用自《Car and Driver》）：

Tesla 在效能上雖然不差，但仍不是最好，不過在一次可行駛里程數上，它的確把一群做汽車做幾十年的老前輩們，遠遠拋在後頭。

大眾知悉Tesla應用18650 鋰電池。它的特色就是在同樣的體積下能夠儲存較多的電能，擁有比其他電池高的能量密度。，搭配Tesla他們專利的電池組裝系統，整車效能表現上，讓其他車廠難以望其項背。
Tesla將與日本的Panasonic或南韓三星電子(Samsung Electronics Co. Ltd.)合作建造電池廠，以獨門科技大幅拉升鋰電池的制造、運用效率，將下一代電動車用電池充飽電量的時間壓縮至一小時內。

一般普羅電池的用戶可能會認為只有一個鋰離子電池。事實上鋰離子電池各有不同，區別主要在於陰極材料。同時，創新性的材料也出現在改良或替換陽極用的石墨。
電池科學家較喜歡使用電池的化學名稱和所應用的材料， 這些名稱可能一時難於理解。下面表格通過其全名，化學的定義，縮略語和縮寫形式列出這些不同鋰離子電池電池，希望提高了清晰度。 

1  陰極材料        2  陽極材料

電動車甪鋰離子電池的比較

電動車電池維護的幾個方法：

• 不可過放電(電池控制器BMS必要機能)。
• 不可過充電(充電器Charger Station必要機能)。
• 不要使用無法充飽電池的充電器。
• 不要使用無過充保護機能的充電器。
• 不要在高溫狀態或場所做充電動作。
• 不可長時間讓電池處於低容量狀態。
• 要長時間儲存時，須放置於陰涼乾燥場所，並適時補充電(依電池廠的建議時限)。
• 常使用的電池每個月須用電池媽媽做１次保養。
• 挑選特性一致的單個電池來組成電池組。(現行產品採用18650型鋰電芯，是鋰電池中最成熟的型號規格。)

本研發中心 (APAS R&D Centre) 成功研發並得廠商應用BMS 和CHAdeMO 制式快速電動車充電器，歡迎各廠商垂詢。