Abstract: A modular external defibrillator system in embodiments of the teachings may include one or more of the following features: (a) a base containing a defibrillator module to deliver a defibrillation shock to a patient, (b) a patient parameter monitoring pod connectable to a patient via patient lead cables to collect patient data, the patient data including at least one patient vital sign, (c) a power supply sharing link between the base and the pod, the pod receiving power from the base via the power sharing link, the pod being operable to collect patient data without receiving power from the base, and (d) an external battery charger, the battery charger interrogating the batteries to determine battery information used for battery charging, the battery information including at least one of charging voltage, charging current, and charge time.