Abstract: A battery pack is effectively transferred between a battery powered vehicle and a cart in order to replace the battery pack with a freshly charged pack. The transfer is facilitated without dropping the battery pack by using a locking mechanism which is operative between a tray which supports the battery pack and a cart upon which the battery pack is transported to the vehicle. The locking mechanism holds the tray in place on the cart until the transfer occurs. The locking mechanism is also operative between the vehicle and the tray to hold the tray and battery pack in place on the vehicle. In order to release the tray from either the cart or the vehicle manual action is required. An attachment mechanism automatically attaches the cart to the vehicle during the transfer to prevent the battery pack from dropping due to unanticipated movement of the cart relative to the vehicle. The attachment of the cart to the vehicle is established upon positioning of the cart in the transfer position.