Hoplite Power is a sharing economy startup that provides a mobile battery rental service for spectators at entertainment venues such as baseball stadiums, arenas, and concert venues. In the U.S., there are live social media activities during live sports games. As a result, people's smartphones often run out of battery during the game. However, convenience stores are not widespread in the U.S., so you can not easily find a mobile battery. Hoplite Power offers a battery rental service for those spectators at the stadium.