An external defibrillator comprising: a unit for providing electrical stimulation of a patient； a battery module that includes: a battery housing； a plurality of battery banks within the housing, each of the battery banks being electrically isolated from each of the other battery banks within the housing and having a total lithium content of less than an amount requiring special handling procedures during transportation and storage； and a plurality of pairs of electrical contacts external to the housing, each of the pairs of electrical contacts being configured to provide an electrical connection to an associated battery bank； and a connector unit external to the battery housing that includes: a plurality of pairs of electrical contacts configured to mate with the plurality of pairs of electrical contacts of the battery module； and circuitry electrically connecting the plurality of pairs of electrical contacts of the connector unit to provide a single voltage output to the unit for providing electrical stimulation.
