A battery system for a movable object is mounted on the movable object having a charger and a load unit including a plurality of loads electrically driven for different purposes. The battery system is provided with a plurality of battery packs, a power control circuit for changing a connection state between the battery packs and the charger and a connection state between the battery packs and the load unit, a memory unit for storing operation information, an estimation unit for estimating a power consumption pattern in the operation cycle based on the operation information and a controller for switching the power control circuit to cover the power consumption by the load unit according to the power consumption pattern.