Converting a lamp for continued operation following a line current failure

A method for converting a lamp having a removable light emitter operable on alternating line current at a voltage exceeding 100 volts to a lamp that continues to emit light in the event of a line current failure, the method comprising:

• replacing said light emitter with a substitute light emitter operable on a DC voltage substantially lower than 100 volts;
• connecting said lamp to the output of a power supply, having an input and an output, said power supply including a charger, connected to said input and output of the power supply, for converting alternating current at a voltage exceeding 100 volts at the input of said power supply to direct current at a low voltage substantially lower than 100 volts and for delivering said direct current to the output of said power supply, said power supply also including a rechargeable battery delivering direct current at a voltage approximately equal to said low voltage, said battery being connected to said output of the power supply and being connected to, and chargeable by, said charger;
• connecting the substitute light emitter to said output of said power supply;
• and
• connecting the input of said power supply to a source of alternating current at a voltage exceeding 100 volts.