System and method of managing battery of vehicle

A system for managing a battery of a vehicle, the system comprising:

• a temperature sensor measuring temperature of external air;
• an electric device cooler including an electric device mounted in the vehicle, an electric device cooling pipe through which cooling water for cooling the electric device flows, and a first pump circulating the cooling water;
• a battery cooler including a battery cooling pipe through which the cooling water for cooling the battery flows;
• one or more 3-way valves connecting or disconnecting the electric device cooling pipe to or from the battery cooling pipe;
• and
• a controller configured to control the first pump and the one or more 3-way valves to move the cooling water in the battery cooling pipe to the electric device cooling pipe when the measured temperature of the external air is a predetermined temperature or less, so as to make an inside of the battery cooling pipe into a gaseous state.