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Electric buses have superior environmental performance because they emit no CO2 and other exhaust gases while driving. However, in terms of more popularization of electric buses, it is essential to improve battery performance and realize user-friendliness of charging. To resolve these issues, a concept “short range running and frequent charging” was formulated. Under this approach, the authors have studied methods of greatly reducing the amount of large, heavy, and expensive battery. Research on non-contact inductive power supply (IPS) system has also been conducted as a way of improving charging convenience. A longterm operation test of electric buses was performed in Nagano prefecture as part of a project organized by the Japan Ministry of the Environment from 2011 to 2014. For this project the short-range frequentcharging type electric buses, “Waseda Electric Buses (WEBs)” were developed and tested on public roads to make clear the environmental performance and energy costs. WEB-3, one of the test vehicles, was driven for 41,724 km without any major problems and had advantages to reduce 28 - 42 % of CO2 emissions and 57 – 64 % of energy costs, compared to conventional diesel buses. And it was estimated on Matlab simulation model that total energy consumption could be reduced by 11 % with vehicle weight reduction, modifications of drivetrain and other components.

The degradation mechanisms of lithium iron phosphate battery have been analyzed with 150 day calendar capacity loss tests and 3,000 cycle capacity loss tests to identify the operation method to maximize the battery life for electric vehicles. Both test results indicated that capacity loss increased under higher temperature and SOC conditions. And also, large increase of internal resistance on the high temperature and high SOC conditions was confirmed by AC impedance tests. The real cycle capacity loss characteristic was derived by subtracting the capacity decrease due to calendar capacity loss during the cycle test from the overall capacity loss characteristic obtained from the cycle test. As a result, it is found that the real capacity loss contains not only structural disorders of electrode but also degradation factors due to the chemical reactions. Characteristics of degradation were quantified with equations based on the chemical kinetics. With this degradation prediction, an operation method was proposed that is compatible with the long life of batteries and the safety driving of a vehicle. As a result, with optimizing the SOC range used in the operation as follows: 30-10% in the warm seasons, 45-25% in the cold seasons, it was found that batteries can last 4 times longer than it used with high SOC range in every season.

Degradation mechanisms of lithium iron phosphate battery have been analyzed with calendar tests and cycle tests. To quantify capacity loss with the life prediction equation, it is seen from the aspect of separating the total capacity loss into calendar capacity and real cycle capacity loss. The real cycle capacity loss of total capacity loss was derived by subtracting the calendar capacity loss parts during cycle tests. It is considered that calendar capacity loss is dominated by SEI formation. On the other hand, real cycle capacity loss includes structure disorder of electrodes and promotion of SEI growth such as delamination and regrowth. Generally, the test results indicated that capacity loss increases under high temperature and SOC condition, and SOC range (ΔSOC) is not related to the loss. However, we founded that the test results under 5℃ condition do not exactly show the same tendency of degradation. As a result, the life prediction equation is based on the chemical kinetics and it can only be adopted only beyond the 15℃ temperature limitation. At this time in life prediction equation, to take ΔSOC into consideration and describe the real cycle capacity loss specifically with amounts of lithium-ion intercalation/deintercalation, the processing amount of current is adopted as the standard of capacity degradation instead of the cycle number. Finally, it is considered to be possible that certain reactions such as further structure disorder or lithium plating caused under low temperature. However, we also founded that DC internal resistance tests results indicated that only calendar capacity loss can apply to chemical kinetics. It is necessary to consider the other construction method of the life prediction equation in the future

This paper presents the results of analysis into the adverse effects on vehicle performance caused by the deterioration in capacity and increase in resistance of lithium-ion batteries installed in hybrid electric vehicles (HEVs). Detailed evaluations were conducted based on simulations to determine the adverse effects on HEV performance. It was concluded that the battery resistance at which the CO2 emissions rate and the Fuel Consumption reaches 120% of the level of a new vehicle is approximately 350% of the initial battery resistance value.

The Waseda Advanced Electric Micro Bus (WEB) has been developed and tested for convenient regional public transportation. By adopting an advanced hybrid electric power supply system (Nickel Sodium Chloride Battery &amp, Super capacitor for WEB-1, Nickel Sodium Chloride Battery &amp, Li-ion Battery for WEB-2) and related key components, significant improvements in energy consumption and CO2 emissions have been achieved, compared to that of an equivalent diesel micro bus.

This paper describes a dynamic simulation model built to assess Plug-in Hybrid Electric Vehicles (PHEVs) performance and lithium-ion battery performance installed in PHEVs. First, we examine vehicle performance. In particular, the effects of engine on/off controls and the effects of drive distance are evaluated, because they have significant impact on PHEVs environmentally friendly performance. A study of cycle life test methods for batteries installed in PHEVs is also examined. Here, we discuss the establishment of a common PHEV battery charge/discharge test profile for Japan, the US, and Europe.