4 years on interstate after they were taken off semi. Still strong they did run down Saturday but it was 20+ mph winds no powerpole, 80 lb fortrex. As said above maintenance is key.
In 2011, I bought 2 Trolling Motor batteries(Everstart) from Wal-Mart....They are still going strong. For the price, these are batteries to consider. Between fishing trips, I leave my Pro Mariner charger on.