A storage system comprising: - a bin storing grid for storing storage bins in columns of the grid; - a base with rails provided on top of the grid; - a vehicle configured to move horizontally along the rails in a vehicle operating space, the vehicle being powered by a rechargeable battery (106a-d); - a charging station assembly for charging rechargeable batteries (106a-d): wherein the vehicle comprises an additional battery allowing the vehicle to move a small distance during an exchange of the rechargeable battery; characterized in that the charging station assembly comprises: - a plurality of charging stations (120a-d) located above each other, each charging station (120a-d) comprising a battery carrier for carrying one of the respective rechargeable batteries (106a-d); - a charging station support configured to support the charging stations in relation to the base; - a transportation device connected to the base for vertical displacement of the charging stations in relation to the base; wherein the charging station assembly is configured to selectively hold one of the charging stations at an exchange location in which the battery carrier of the one charging station is at a predetermined height above the base; wherein the transportation device is configured to vertically displace other charging stations (120b-d) to an upper location above the vehicle operating space or to a lower location below the vehicle operating space; wherein the vehicle is configured to move horizontally towards the battery carrier which is held at the exchange location to deliver its rechargeable battery (106a-d) which is in need of charging to the battery carrier; wherein the vehicle is then configured to move horizontally a predetermined distance away from the battery carrier enabling the charging station assembly to vertically displace another rechargeable battery (106a-d) which has been charged to an operational level to the exchange location, and the charging station assembly is configured to vertically displace the other rechargeable battery (106a-d) to the exchange location; and wherein the vehicle is configured to move horizontally towards the battery carrier again for delivery of the other rechargeable battery (106a-d) from the battery carrier to the vehicle. - a bin storing grid for storing storage bins in columns of the grid; - a base with rails provided on top of the grid; - a vehicle configured to move horizontally along the rails in a vehicle operating space, the vehicle being powered by a rechargeable battery (106a-d); - a charging station assembly for charging rechargeable batteries (106a-d): wherein the vehicle comprises an additional battery allowing the vehicle to move a small distance during an exchange of the rechargeable battery; characterized in that the charging station assembly comprises: wherein the vehicle comprises an additional battery allowing the vehicle to move a small distance during an exchange of the rechargeable battery; characterized in that the charging station assembly comprises: - a plurality of charging stations (120a-d) located above each other, each charging station (120a-d) comprising a battery carrier for carrying one of the respective rechargeable batteries (106a-d); - a charging station support configured to support the charging stations in relation to the base; - a transportation device connected to the base for vertical displacement of the charging stations in relation to the base; wherein the charging station assembly is configured to selectively hold one of the charging stations at an exchange location in which the battery carrier of the one charging station is at a predetermined height above the base; wherein the transportation device is configured to vertically displace other charging stations (120b-d) to an upper location above the vehicle operating space or to a lower location below the vehicle operating space; wherein the vehicle is configured to move horizontally towards the battery carrier which is held at the exchange location to deliver its rechargeable battery (106a-d) which is in need of charging to the battery carrier; wherein the vehicle is then configured to move horizontally a predetermined distance away from the battery carrier enabling the charging station assembly to vertically displace another rechargeable battery (106a-d) which has been charged to an operational level to the exchange location, and the charging station assembly is configured to vertically displace the other rechargeable battery (106a-d) to the exchange location; and wherein the vehicle is configured to move horizontally towards the battery carrier again for delivery of the other rechargeable battery (106a-d) from the battery carrier to the vehicle.