How long does your Optima battery last?

14 years. Car stored outside, for up to 7 months per year, in the snow, at up to -35*C, with pos disconnected. Tremendous value. Iso field alt with constant voltage reg. One piece wire from alt to ammeter. Installed in trunk; neg cable bolted to rear stub frame, engine grounded to front stub frame. Same alt frame, albeit with periodic bearing and brush changes. The CV reg had to be replaced once due to overcharge (went to 20vdc at idle).