It depends on how many of the 4 battery back-up sockets you are using and how much power your devices are using when a power failure occurs. I use 3 of these sockets (computer with i7 processor, monitor, and back-up hard drive) and had enough time to save the files I was working on, close all open windows, and shut down my computer. However, I did not test the extremes for the battery. According to the User Guide, the battery runtimes range from 65 minutes for a DVR that is recording, to 18 minutes for a 21" iMac computer, to 6 minutes for a 32" LCD TV and PS3 console. These times are similar to the competitor's times, and plenty of time to back up files, close programs and shut down devices safely.
Hope this helps.
Bob