Have you wondered about those battery backups like Trip-Lite and APC? John Carter has some information that will help solve the question.
John gets our attention here: "There’s nothing like a chit-chat between a disillusioned user and an expert to clear up misconceptions about something. This is the case regarding battery backups and why they sometimes do not last as long as the warranty. The conversation in this online thread at HardwareAnalysis.com about battery backups is really worth reading from top to bottom. You’ll find out why choosing the right battery backup for your electronic devices is essential and come away understanding why one with a two year warranty would fail long before its time or may last much longer. The expert also identifies several specs to consider aside from just the power rating. Naturally, the more demanding your needs are the more costly the battery backup will be."
John goes on, "To figure out what size of battery backup is needed, total up the power consumption of all the devices you want to protect and buy a battery backup that can provide at least that much power.
"For instance, the Tripp-Lite sold at Costco is rated at 500W. I use these units throughout my house to protect everything electronic: one in the bedroom for the entertainment system there, another in the living room for that entertainment system, and one each for the two computer systems in the study.
"I doubt that any combination of components for a computer system would exceed 500W. However, a 21” iMac draws about 200W and hence dictates that a 300W battery backup (Tripp-Lite here or APC here) is the minimum to use."
Here John concludes, "Also, depending on the number and type of components in an entertainment system the total power could exceed 500W (an A/V receiver rated at 100W per channel draws 500W total for a 5.1 speaker system at full volume) and warrant more than one battery backup device."