The backup won't run the computer system that long either.  If you don't 
transmit on the radio, ormaybe  run  you might an hour or two.  We lost 
power one night for about two hours.  I pluged my 480 in to the ups, and was 
absolutely amazed at what I could hear with no power in the neighborhood. 
Oh well all good things come to an end, and the next day my noise floor was 
back.  I think their was a 5 S unit difference.qrp cW,