A.quality deep cycle RV / Marine battery should last 4 years or more. Even though deep cycle batteries are designed to be discharged never completely discharge the battery. Also check the electrolyte level frequently. There is no need to remove the battery during winter storageas long as you disconnect the cable or Turn off the battery switch. Cold is not the enemy of your battery heat Is. Be sure your battery has a full charge when it is put away for the winter. A battery minder is always a good idea if you have electric near where you store.