Electric Vehicles (EVs) have attracted attentions as global warming countermeasures. In particular, Battery EVs (BEVs) are more attractive in terms of no carbon dioxide emissions. This study focuses on Battery Swapping EV, which is next-generation BEV. This type of BEV has great advantage on fulfilling electrical power by battery swapping within few minutes. Development of new battery swapping EV, however, requires a lot of initial costs. Installing BSS (Battery Swapping Station) and/or deployment of spare batteries on BSSs are examples of them. If we can utilize those spare batteries for the purpose other than the EV mobilities, development of the service becomes much easier. Hence, for the purpose of using spare batteries in BSS as an emergency power supply, this paper proposes a new method to equalize charged electricity of spare batteries by EV electricity transportation between BSSs. However, considering only amount of carried electricity induces unnecessary increase of EV users’ load. Therefore, this paper also proposes a method avoiding unneeded battery carry on the basis of advanced investigation of BSS state through network communications. The results of performance evaluation confirm that the proposed method can equalize the amount of charged electricity among BSSs while minimizing EV users’ load.