Patent ID: 7728525

Claim:
An battery powered ballast for use in combination with a primary ballast, said primary ballast powering a lamp when operably connected to and energized by a power supply, said battery powered ballast for use with a battery and for powering the lamp when the primary ballast is not energized by the power supply, said battery powered ballast comprising: a lamp driver circuit for supplying power to the lamp from the battery when said lamp driver circuit is enabled; a first switch circuit for selectively connecting the lamp to the lamp driver circuit or the primary ballast; a second switch circuit connected to the power supply for connecting the primary ballast to the power supply when the power supply is energizing the second switch circuit such that the primary ballast is energized by the power supply, and for enabling the lamp driver circuit when the power supply is not energizing the second switch circuit; and a relamping circuit for toggling the first switch circuit in response to a power restoration event comprising the power supply energizing the second switch circuit after a period during which the second switch circuit was not energized by the power supply.