Battery life depends on a number of key factors. These include:
Operating temperature of the battery
Method of charging utilized
Actual use of the product i.e.: float or cycle service.
The estimated life under float service is 3 - 5 years for battery with capacity ≤ 26AH. The float service is affected by the factors listed above and the number and depth of discharges the battery suffers during its lifetime. Basically the more discharges suffered and the deeper the discharges, the shorter the battery life.
Cycle Service (For the Deep Cycle series EV or EVS series )
Giving due consideration to the above factors, the actual life of a battery in cycle service is dependent on the depth of discharge of each cycle. The greater the depth of discharge of each cycle the lesser the number of cycles available from the battery.