How much does a typical Energy-XS backup system store? (in hours assuming one LED lamp produces illumination equal to a 100W incandescent lamp) Why recommended LED lamps?

A typical 100w bulb produces 900 to 1000 lumens of illumination, and normally this light is omnidirectional. If all this light was made more directional as in an LED lighting source, we have a 100W bulb then producing 9 lumens per watt. Compare this with an LED light source which produces 100 Lumens for every watt, requiring just 9 watts to produce the same intensity as a 100W bulb! A 7AH battery can then store enough backup power for 9 hours.