An automated or semi-automated defibrillator (AED) system includes an AED and a cartridge attachable to the AED. The cartridge includes electrode pads and a power source such as a battery or fuel cell, which may recharge a defibrillator battery, power defibrillator circuitry, or both. Because the cartridge includes both a power source and electrode pads, one can replace the power source and the pads at the same time by replacing a single cartridge. Furthermore, in defibrillator systems where the power source charges the defibrillator battery, the power source can be selected to have the same life as the pads, thus making it practical to replace the power source and pads at the same time. In addition, maintenance for such a charging defibrillator system typically costs less than for a non-charging system because it often costs less to replace the power source than to replace the defibrillator battery.