A good UPS (bat backup) will do the same thing, but give you a controlled, and timed power off when the bat runs to a low voltage set point. No time to search right now, but look for one that converts AC to DC, then back to AC. The conversion transformer will give you clean, uninteruped 60 cycle power.
I guess I should mention that I used to be a power plant control room / switch board operator. All plants convert and clean power they produce for electronic controls within the plant. That's a small tidbit for a bit of perspective.
