My 3 home computers has it's own power backup. The thought occurred to me tonight; how can I know the battery life is still good? They vary in age 2-5 years. It has, fortunately, been some time since a power surge or lightening strikes nearby caused a power outage. I do not recall if either of the battery backups kept the computer on for a few minutes. If it didn't, than I have my answer--the battery is shot. These backups are 350W and 450W and 8Amps. If the battery is dead then they are acting only as power strip without any protection. That is my guess but I would like to receive your input. As usual, TIA.