1 year, 4 months old and my optima red top is a goner. Measures 5.8 volts. Oh well, its nice to have a bunch of other batteries just laying around, and its got a 3 year free replacement guarantee on it...so I'll get a new one when I get home.. I'm just disappointed that it didn't last longer. I do have my suspicions that I got a dud though, its never been full voltage.