Among transportation-related issues, the most effective measure for resolving the problem of oil resources is the electric car. The key to the practical use of electric cars is cell batteries, which are the source of power for such cars. From this point of view, we have conducted experiments to prove that a speed of 100 km/h can be achieved by using size-AA dry-cell batteries [JIS,2006], in order to promote the efficiency of electric cars among the general public. This paper describes the results obtained from studies conducted into the optimization of the battery-cell system, which is an important parameter for this project. In this study, Oxyride dry-cell batteries, developed by Matsushita Battery Industry Co., Ltd, were selected and used, since they are higher in output power and energy, and content than traditional alkaline dry-cells. The study results indicate that, when using these batteries in an area of large current discharge, safety and the highest efficiency are achieved when they are heated to 60°C. Based on these results, an optimal battery system using size-AA battery-cells was examined in order to achieve a speed of 100 km/h with a person on board a car, and the outcomes of this examination are described in this paper.