I've been searching for a product that doesn't seem to exist.

In my parents' house, they're set up with an X10 system that's working quite well except for one problem. The main controller gets its power from the wall, and has no batteries. This wouldn't be too much of a problem but for two things: the house loses power briefly almost every other day, and the only thing the controller doesn't store in memory is the time and date.

So right now the lawn lamps are probably on because I haven't gotten over there to set the time yet (my mom doesn't know how).

What I would love to find is a very small battery backup that could handle one device for a very short amount of time. This controller couldn't draw much power, and the power usually only goes out for a few minutes at most.

Does any such device exist? The smallest I've been able to find are still about the size of a loaf of bread. I understand that these things need huge batteries, but that's for keeping computers/monitors running for a couple minutes. All I need to do is keep a 4" 2-color LCD screen going for a minute or two.