A substantially uninterruptible backup power system to provide power to common household appliances comprises a rechargeable battery, a trickle-charging circuit to keep the battery fully charged at all times from the receptacle power, a DC to AC inverter to supply standard AC line voltage from the battery to the lamp, a relay switch, controlled by main power voltage, to switch to the backup system when main power fails, and a timing circuit to optimize a voltage output of the system based on current battery voltage and a desired time period for the voltage output. The system can be set to operate only when the appliance is turned on, which optimizes the current and power required to provide backup power to the appliance for a maximum period of time.