What is 1D-II battery life span?

Do they wear out after a 18 months of use or can you continue using them for many years?

I'm not talking about how many shots per charge, but how many years of recharging before the battery needs to be replaced.

Im sure they will last you longer than 18 months. It does depend on how much you are shooting, but you will be fine. Be sure to drain and fill them once in a while as well.

I used 1D classic batteries 5 years old plus. It is the same battery. They didnt hold charge well after about 3+. I like old dead 1D batteries though. Ill take as many as I can get. The major diff is the MKII doesnt put the drain on that the classic does, so the life may be longer.