I have an APC battery back-up on my computer and LAN. After a few years the batteries no longer passed a self-test. I bought some replacement cells at a local battery supply. They are supposed to hold more power But after a year the Unit complained the batteries would not pass a self-test anymore and needed replaced. Well it worked fine other than that so I pretty much ignored the battery warning going on over a year now.. Last night the power was off for 5 hours, the Battery back-up went totally dead and recharged when the power came back on. It now passes a self-test. I'll take it!!