A control module for an electrical stimulation system includes a sealed electronics housing； an electronic subassembly disposed within the electronics housing； one or more connector assemblies coupled to the electronic subassembly； and a rechargeable battery disposed external to the electronics housing. The one or more connector assemblies are configured to receive a lead. The rechargeable battery includes a positive electrode, a negative electrode, and a single battery case attached directly to the sealed electronics housing and forming a sealed cavity that encapsulates both the positive electrode and the negative electrode. The battery case is electrically isolated from each of the positive electrode and the battery electrode.
