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It is important to make small and light weight motor for small EV. It is necessary to select appropriate cooling system (liquid cool or air cool) according to motor output. We thought that there is a threshold output that makes the volume smaller and the weight lighter including the liquid cooling system. As a result of the rough calculation, it was found that the weight can be reduced by adopting the liquid cooling for at about 10kW or more. In this study we focused on motor and cooling system volume and weight and tried to clarify appropriate cooling system according to motor output.

Yamaha Motor Co., Ltd. has been developing 1kW generator system of direct methanol fuel cell (DMFC). The performance and durability characterization of a 1kW DMFC stack that the weight of the stack was decreased 20% in comparison with that of previous stack was evaluated. The DMFC operation condition was optimized from the design of experiment and the results of the net output. The overall system efficiency of the Yamaha DMFC system using the stack became a maximum in current 20A, was 30%. The stack was generated at 20A under the Daily Start up and Shutdown (DSS) condition for 1500h. This report describes some latest results concerning the durability characterization, which were obtained in the NEDO's project.

Yamaha Motor Co., Ltd. succeeded in the development of a direct methanol type fuel cell (DMFC) powered motorcycle named the FC-me in 2005. (1) One of these models was leased to the Shizuoka prefecture government office in September of that year. During the course of this leased use a number of changes were observed in the performance of the fuel cell and the emissions, etc. As a result, it was learned that the cycle of starting and stopping had a major effect on the efficiency of the fuel use. In this report we introduce the results of the period of leased use and observations about the ideal format of the next-generation fuel cell motorcycle based on those results.

Direct methanol fuel cell (DMFC) system is a compact lightweight system as it eliminates the need of a complex reformer unit. Moreover, since the methanol-water-solution used as fuel does not correspond to a flammable substance, it is thought that convenience is high. We have developed the hybrid scooter integrated with the DMFC system and the Li-ion rechargeable batteries, and optimized various parameters related to the performance and the efficiency. The power output of the DMFC system was adjusted to the value necessary for a constant ground run in 30 km/h of a commercial small electric scooter. All the system components had to be constituted in the limited space and under the restricted weight conditions. The net-power-output of the system was examined under various air flow rate, fuel flow rate and methanol concentration conditions.