Lithium Ion batteries and especially Lithium Iron Phosphate (LFP) batteries can be characterized by high power densities, relatively long life-time, no maintenance and a lot of research currently being done on increasing their performance. Therefore, they seem to be a good choice for integration with wind turbines. However, the current Lithium Ion energy storage price and its limited lifetime are the main obstacles to the integration of storage technologies with wind turbines. That is why proper lifetime estimation of the lithium ion batteries, working with mission-profile characteristics for specific services, is very important, not only for optimisation of the revenues but also for correct scheduling of the maintenance jobs. This paper analyzes the connection of LFP battery storage systems into wind turbines, with a high focus on the lifetime of LFP batteries for selected services.