To replace a depleted battery in a drone with a fresh battery, the drone first lands on the exchange and charging system, aligned between two battery holders. A freshly charged battery, in a docking bay in one battery holder, is then moved against the drone's depleted battery. The depleted battery, in turn, is moved out of the drone into the other battery holder, and the fresh battery takes its place. While in the battery holders, the batteries are charged. After a battery exchange, the battery holders track round so that another battery and vacant docking bay are brought into place for a subsequent exchange.