They lasted 7-8 years before all the buzzing stayed sort of permanant. It was odd one of the UPS the battery was slightly smaller but I used the same battery when I bought 2 to replace and I could not get the 'door' back on one. But they are on a shelf. There may be things plugged in that aren't there to be plugged in. I have had 4 computers, 4 printers and more power bricks and wall warts surely more than there are devices using them now. One day I need to unplug everything and start over . I have been in this apartment for nearly 15 years. $30 each was not bad . I have to think about my car. I bought a battery for it about 3 years ago. It was a "4" year battery. The car was new in 07 and only has 25k on the odo. But that one is over $100.