1. A rechargeable battery interconnected smoke detector system comprising:a plurality of smoke detectors to electrically couple to a dedicated circuit;
a rechargeable battery located inside a case of one of the plurality of smoke detectors; and
a first relay to directly electrically couple to the dedicated circuit, an alternating current source, and the rechargeable battery,
wherein the first relay is to selectively conduct an alternating current from the alternating current source to the dedicated circuit to power the plurality of smoke detectors under a condition wherein the alternating current source is present and selectively conduct a direct current from the rechargeable battery to the dedicated circuit to power the plurality of smoke detectors under a condition wherein the alternating current source is not present.