Concerns about climate change and energy costs are key drivers in the growth oí Battery Vehicle (BV) utilization. In the Vehicle-to-Grid (V2G) paradigm, an aggregation of BVs is used for the provision of energy and capacity services, including ancillary services to the grid. Participation in the V2G framework may entail additional charge and discharge of the BV batteries, leading to reduced life. In this paper, we discuss the formulation of an effective strategy for the aggregator, whose role in the effective implementation of the V2G framework is pivotal, to manage the aggregated vehicles, so as to maximize the total lifetimes of all the batteries in the aggregated BVs. The proposed management strategy makes use of both the state of charge (s.o.c.) and the state of health (s.o.h.) as key variables in the allocation of the service request to the BV batteries. Each service request is considered in terms of its impacts on both the individual and the entire BV aggregation battery health, so to allocate the service provision in the configuration that determines the least decrement in battery life. We explicitly assume the aggregator is responsible for the acquisition and maintenance of the batteries of the aggregated BFs and so the maximization of the aggregation battery life is simply the preservation of the value of the aggregator's assets. We illustrate the effectiveness of the approach with simulation results that indicate the success in battery life preservation, with notable improvement over the cases based solely on the use of s.o. c as the key variable.