The typical overall life of a deep cycle battery is:

Purpose Life
Starting (Used as a Deep Cycle) 0 to 12 months
Marine/RV up to 6 years
Golf Cart up to 6 years
Gelled Deep Cycle up to 8 years
AGM up to 10 years
Ni-Cad up to 10 years
Telecommunications (Float) up to 10 years
Fork Lift up to 10 years
Industrial (Traction) up to 20 years
Industrial (Stationary) up to 20 years
Ni-Fe up to 20 years

Recharge a deep cycle battery as soon as possible after each use and maintain the State-of-Charge at 100% to prevent sulphation. When in storage, recharge when the State-of-Charge drops to 80% to prevent lead sulphation or continuous float charging which is better because it will prevent sulphation.

Lowering the average DoD (Depth-of-Discharge) significantly increases the battery life. For example, a battery with an average of 50% DoD will last twice as long or more as an 80% DoD; a 20% DoD battery will last five times longer than a 50% DoD. For example, golf cart batteries will average 225 cycles at 80% DoD and increase to 750 cycles at 50% DoD. Try to avoid DoD that are less than 10% or greater than 80%. Industrial traction, golf cart, and stationary deep cycle batteries are designed for 80% DoD and most Marine/RV deep cycle batteries are designed for 50% DoD.

In hot climates and during the summer, "watering" is required more often. Check the electrolyte levels and add only distilled water, if required. Never add electrolyte (battery acid) to a battery that is not fully charged and do not over fill. The plates must be covered at all times.

Avoid high ambient temperatures (above 80°F or 26.7°C). This will shorten battery life because it increases positive grid corrosion and growth.

Recharge slowly with the manufacturer's recommended voltages and keeping your battery well maintained.

Maintaining the State-of-Charge over 80%, topping up electrolyte levels, tightening loose hold-down clamps and terminals, and removing corrosion is normally the only preventative maintenance required for a deep cycle battery.

Never discharge below 10.5 volts. Low voltage disconnection devices can limit the average Depth-of-Charge and protect electrical appliances.