Abstract: Systems to retain a battery within, and to eject a battery from, a battery receptacle of a medical device, such as a portable defibrillator, are described. A battery receptacle of a medical device includes an element that is configured to engage an inserted battery to prevent, or reduce, movement of the battery within the receptacle and to assist with removing the battery from the receptacle. In an example, the element is a monolithic structure that includes a retention portion and an ejection portion. The retention portion is positioned at a side wall of the battery receptacle, and the ejection portion terminates in a free end positioned a distance from the side wall. When the battery is inserted into the battery receptacle, the retention portion exerts a retention force on a side surface of the battery, and the ejection portion exerts an ejection force on an end surface of the battery.