This one says that it should give 20-25min of power on average. Considering I'm only plugging a few christmas lights into it, that should be enough?

http://www.amazon.com/APC-BE550G-Back-UPS-8-outlet-Uninterruptible/dp/B0019804U8/ref=pd_sim_23_4?ie=UTF8&dpID=41zxR4DV2BL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=19E2CN28X2M9RF95JDCC